ZyXEL Communications U-336R, U-336RE User Manual

U-336R/RE

User’s Guide

Version 1.0
(Mar. 1997)

ZyXEL

ACCESSING INTERNET & INTRANET

ZyXEL Limited Warranty

ZyXEL warrants to the original end user (purchaser) that this
product is free from any defects in materials or workmanship for a
period of up to two (2) years from the date of purchase. During the
warranty period, and upon proof of purchase, should the product
have indications of failure due to faulty workmanship and/or
materials, ZyXEL will, at its discretion, repair or replace the
defective products or components without charge for either parts or
labor, and to whatever extent it shall deem necessary to restore the
product or components to proper operating condition. Any
replacement will consist of a new or re-manufactured functionally
equivalent product of equal value, and will be solely at the
discretion of ZyXEL. This warranty shall not apply if the product is
modified, misused, tampered with, damaged by an act of God, or
subjected to abnormal working conditions.

Note: Repair or replacement, as provided under this warranty, is
the exclusive remedy of the purchaser. This warranty is in lieu of all
other warranties, express or implied, including any implied warranty
of merchantability or fitness for a particular use or purpose. ZyXEL
shall in no event be held liable for indirect or consequential damages
of any kind or character to the purchaser.

To obtain the services of this warranty, please contact ZyXEL’s
Service Center, refer to the separate Warranty Card for your Return
Material Authorization number (RMA). Products must be returned
Postage Prepaid. It is recommended that the unit be insured when
shipped. Any returned products without proof of purchase or those
with an out-dated warranty will be repaired or replaced (at the
discretion of ZyXEL) and the customer will be billed for parts and
labor. All repaired or replaced products will be shipped by ZyXEL
to the corresponding return address, Postage Paid (USA and
territories only). If the customer desires some other return
destination beyond the U.S. borders, the customer shall bear the
cost of the return shipment. This warranty gives you specific legal

ii

rights, and you may also have other rights which vary from state to
state.

Copyright © 1997 by ZyXEL

The contents of this book may not be reproduced (in any part or as
a whole) or transmitted in any form or by any means without the
written permission of the publisher.

Published by ZyXEL Communications Corporation. All rights
reserved.

Note: ZyXEL does not assume any liability arising out of the
application or use of any products, or software described herein.
Neither does it convey any license under its patent rights nor the
patents rights of others. ZyXEL further reserves the right to make
changes in any products described herein without notice. This
document is subject to change without notice.

Acknowledgments

Trademarks mentioned in this manual are used for informational
purposes only.

Trademarks are properties of their respective owners.

FCC Part 15 Information

This device complies with Part 15 of FCC rules. Operation is
subject to the following two conditions:

1. This device may not cause harmful interference.

2. This device must accept any interference received, including

interference that may cause undesired operations.

This equipment has been tested and found to comply with the limits
for a CLASS A digital device pursuant to Part 15 of the FCC
Rules. These limits are designed to provide reasonable protection
against harmful interference in a commercial environment. This
equipment generates, uses, and can radiate radio frequency energy,

iii

and if not installed and used in accordance with the instructions,
may cause harmful interference to radio communications.

If this equipment does cause harmful interference to radio/television
reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference by
one or more of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment and the receiver.

• Connect the equipment into an outlet on a circuit different from

that to which the receiver is connected.

• Consult the dealer or an experienced radio/TV technician for

help.

Changes or modifications not expressly approved by the party
responsible for compliance could void the user’s authority to
operate the equipment. Shielded RS-232 cables are required to be
used to ensure compliance with FCC Part 15, and it is the
responsibility of the user to provide and use shielded RS-232
cables.

iv

Information for Canadian Users

The Industry Canada label identifies certified equipment. This
certification means that the equipment meets certain
telecommunications network protective, operation, and safety
requirements. The Industry Canada does not guarantee that the
equipment will operate to a user’s satisfaction.

Before installing this equipment, users should ensure that it is
permissible to be connected to the facilities of the local
telecommunications company. The equipment must also be installed
using an acceptable method of connection. In some cases, the

company’s inside wiring associated with a single line individual
service may be extended by means of a certified connector
assembly. The customer should be aware that the compliance with
the above conditions may not prevent degradation of service in
some situations.

Repairs to certified equipment should be made by an authorized
Canadian maintenance facility designated by the supplier. Any
repairs or alterations made by the user to this equipment, or
equipment malfunctions, may give the telecommunications company
cause to request the user to disconnect the equipment.

For their own protection, users should ensure that the electrical
ground connections of the power utility, telephone lines, and
internal metallic water pipe system, if present, are connected
together. This precaution may be particularly important in rural
areas.

Caution: Users should not attempt to make such connections
themselves, but should contact the appropriate electrical
inspection authority, or electrician, as appropriate.

This digital apparatus does not exceed the class A limits for radio
noise emissions from digital apparatus set out in the radio
interference regulations of Industry Canada. The declarations of CE
marking:

This product has been approved for connection to the Public
Switched Telecommunication Network using interfaces compatible
with ITU-TSS recommendation I.420. This product complies with
the following directives:

v

1. The Council Directive 89/336/EEC of 3 May 1992 on the

approximation of the laws of the member states relation to
Electro Magnetic Compatibility. (EMC Directive)

2. Council Directive 91/263/EEC of 29 April 1991 on the

approximation of the laws of the Member States concerning
telecommunication terminal equipment. (The Telecom Terminal
Equipment Directive)

3. 93/68/EEC of 22 July 1993 amending the Directives

89/336/EEC, 91/263 /EEC and 92/31/EEC.(Marking Directive)

The Council Directive 92/31/EEC of 28 April 1992 amending

directive on the approximation of the laws of the member states
relating to electromagnetic compatibility.

Contacting ZyXEL

If you have questions about your ZyXEL product or desire
assistance, contact ZyXEL Communications Corporation in one of
the following ways:

• Phone: In North America call between 8:00 AM and 5:00 PM

PST at [phone]

vi

Outside North America, you can dial [phone] EXT

252 between 8:00AM and 5:00PM Taiwan time (GMT +8:00).

• Fax: ZyXEL in North America: [phone] or Taiwan:

[phone]

• E-mail:

• Sales inquiries: [e-mail] in North America.

[e-mail] outside North America.

• Technical support: [e-mail] in North America.

[e-mail] outside North America.

• Product information: Visit our site on the World Wide Web:

http://www.zyxel.com.

• FTP: Information , such as ZyXEL software and ROM updates

for North America can be found at this FTP address:
ftp.zyxel.com

For European and Asian versions and related files, use the

address: ftp.zyxel.co.at

• Postal Service: You can send written communications to the

following address:

ZyXEL Communications Corporation
6, Innovation Road II, Science-Based Industrial Park
Hsinchu, Taiwan 300, R.O.C.
or
ZyXEL Communications Inc.
4920 E. La Palma Avenue
Anaheim, CA92807, U.S.A.

vii

Contents

1 Introduction 1

2 Installation 7

ZyXEL Limited Warranty ii
FCC Part 15 Information iii
Information for Canadian Users iv
Contacting ZyXEL vi

What This Manual Covers 1
Modem Features 1

Standard Features 1
Intelligent Features 2
Fax Compatibility 3
Technical Specifications 3

Unpacking Your Modem 4

Enclosed Equipment 4
Required Equipment 4

Becoming a Registered Owner 5

U-336R/RE Modem Card 7
Required Steps for U-336R/RE Installation 9

Installing the modem card 10
Connect to phone lines 10
Connect to Computers 11
Hooking Up Power 11
Fax/Modem Communication Software Installation 11

viii

3 Basic Modem Operation 15

Understanding AT Commands 15

Using the Windows 95 Hyper Terminal Program 15

Dialing and Answering Techniques 17

Dialing using the ATD Command 17
Auto-Answer and Hook Controls 18

Making Your First Connection 18
Quick Tips when issuing AT Commands 19

Modem Result Codes 21
Viewing S Register Values 22
Changing S Register Values 22

Non-Volatile Memory 23

Storing Phone Numbers 23
Dialing Stored Phone Numbers 23
Saving Settings and User Profiles 24

Helpful Hints for PC Computers 24

Default Modem Settings for PC’s 25
ZyXEL Serial/Parallel I/O Card 25

Helpful Hints for Macintosh Computers 26

Special AT Command Settings for Macintosh 26
Macintosh Serial Port 26
Mac Software Tips 26

Helpful Hints for UNIX-Based Computers 27

Serial Cable 27
Basic Modem Settings for UNIX 27
Unix Software Tips 28

4 Synchronous Mode Operation 29

V.25bis Command Set 29
Clock Options 30
RTS Options 31
Command State Options 32
Dialing from Synchronous Mode 32
Answering from Synchronous Mode 33

Auto-Answer 33
Manual Answer 33

5 Leased Line Operation 35

ix

Connecting to a Leased Line 35

Line Type Setting 35
Power Level Setting 36

Leased Line Handshaking 36

Manual Connect 36
Auto Handshake 36

Leased-Line Dial Backup 37

Dial Backup 37
Aborting from Leased-Line Operation 38

Terminating a Leased Line Connection 38

6 Special Functions 39

Security Functions 39

Levels of Security 39
User Passwords 40

Remote Configuration 42
Caller Number Delivery (Caller ID) 43
Distinctive Ring 46
Extended Distinctive Ring (EDR) 47

Setting Up EDR 49
EDR Application Example 50

7 Fax Operation 53

Modem as Fax Machine 53

ITU-T T.30 Fax Protocol 54

Fax Command sets 54

Defining the Fax Command Sets 54
Class 1 Command Set 55
Class 2 Command Set 56
Class 2.0 Command Set 63
Extended Fax AT Command Set 70
Flow Control 74

Fax Reception from a BBS 75

x

8 AT Command Set Summaries 77

Basic AT Command Set 77

Description of ATI2 Output: 80

Extended AT& Command Set 83
Extended AT* Command Set 89

9 Status Registers & Result Codes 92

S-Register Descriptions 92

Basic S-Registers "ATSn=x" 92
Extended S-Registers "ATSn=x" 93

Result Code Options 111

"ATXn" Result Code Option Table 111
Result Code Field Descriptions 113
Connect Strings for Error Corrected Connections 113

10 Diagnostics & Troubleshooting 116

Diagnostics 116

Power-On Self Test 117
Loopback Tests 118
Indicator Lights 119
Line Condition Status Display 120
Link Status Report (ATI2) 122

Trouble Shooting 126

AT Command Set Problems 126
Command Echo Problems 128
Answer Problems 128
Dialing Problems 129
Data Transfer Problems 130
Connect Problems 130

11 Upgrading Your Modem 131

Upgrading by Flash EPROM 131
Kernel Recovery Mode 132

xi

12 Terminal Pinouts 133

Terminal Blocks 133
PC Serial Port Pinouts 134
Macintosh Serial Port Pinouts 135

13 Index 137

xii

1 Introduction

What This Manual Covers

Congratulations on the purchase of your U-336R/RE modem - one
of ZyXEL's premier high-performance products. The U-336R/RE
modem cards are world renown for their ability to maintain ultra
high speeds and clear, quality connections while communicating
around the globe.

Modem Features

No other 33.6 Kbps modem gives you so much for so little. Your
modem is equipped with an array of standard and Intelligent
features designed to make your data communications faster, easier,
and more convenient.

Standard Features

• Supports V.34 for 28,800bps and is backwards compatible.

• Operates in all environments including: Windows 95, DOS,

Windows, Macintosh, OS/2, UNIX, Novell, Amiga, and IBM
AS400/RS6000.

• V.42 and MNP 4/3 error correction.

• V.42bis and MNP 5 data compression.

• DTE serial interface with speeds up to 460.8Kbps.

Introduction 1

• 14 LED indicators (RE/RD).

• 15 LED indicators (R).

• Extended AT command set with V.25bis.

• Operates on 2-wire dial-up or 2-wire leased line (RE).

• Operates on 2-wire dial-up or 2/4-wire leased line (R).

Intelligent Features

• Automatic data, and fax call detection allows you to use a

single telephone line to handle both voice and data calls.

• Asynchronous and synchronous modes for reliable serial data

communication.

• Fast retrain with automatic fall-forward and fall-back. Your

modem will automatically fall back to lower speeds when
communicating with slower modems and when encountering
unstable or variable line conditions.

2 Introduction

• Call-back security and password protection restricts access to

authorized callers only.

• Caller ID identifies incoming calls before you answer (you must

subscribe to this service through your telephone company in
order for your modem to identify callers).

• Distinctive ring detects data, fax and voice calls (this feature

requires communication software that supports distinctive ring,
such as ZFAX)

• Remote configuration capability.

• EDR (extended Distinctive Ring).

• Flash EPROM memory lets you easily upload new firmware,

providing you with easy access to new features.

• ZyXEL exclusive Kernel Recovery Mode for no hassle recovery

from failed flash uploads - no factory repairs.

Fax Compatibility

• EIA Class 1, 2, and 2.0 Fax commands.

• ITU-T V.17 G3: up to 14,400bps.

• ITU-T V.29 G3: up to 9,600bps.

• ITU-T V.27ter G3: up to 4,800bps.

• ZyXEL Fax AT commands.

Technical Specifications

• Operating mode: auto-dial/answer.

• Flow control: software XON/XOFF or hardware CTS/RTS.

• Data/Voice toggle switch.

• Configuration settings: software programmable with non-

volatile memory for phone number/profile storage.

• Diagnostics: self test, analog loopback (with self test), digital

loopback, and remote digital loopback (with self test).

• Dialing type: tone/pulse dialing.

Introduction 3

• Line interface: 2-wire dial-up or 2-wire leased line (RE).

• Line interface: 2-wire dial-up or 2/4-wire leased line (R).

• Call progress monitoring: dial tone, busy, and ring back

detection.

• Audio Monitor: programmable volume control.

Unpacking Your Modem

Enclosed Equipment

Before you proceed further, please check all items you received
with your modem against this list to make sure nothing is missing.
The complete package should include:

• One U-336R/RE universal modem.

• One warranty/registration card.

Contact your dealer or the store where you bought the modem if
anything is missing. Check the modem for shipping damages. If you
find any damage, contact the shipping agency immediately.

4 Introduction

Retain shipping and cushioning materials for future storage or
shipping needs.

Please direct any additional questions about damaged or missing
materials to your dealer or distributor, or see page vi to contact
ZyXEL.

Required Equipment

In addition to the ZyXEL modem you just purchased, you must
have the following equipment to operate your modem:

• Computer terminal.

• Available PC serial port with a high-speed 16550 UART.

• Standard "straight-through” RS-232 cable (pins 1-8, 20, 22).

• Available telephone jack.

• Available AC wall outlet.

• Telephone line from your telephone company (dial-up or leased

line).

• Data and fax communication software.

Becoming a Registered Owner

Complete the pre-addressed Warranty Registration Card and place
it in the mail. Registered owners will receive future product
information and update announcements. Warranty registration is
not necessary for product repair or replacement. Also save your
dated invoice as proof of purchase.

Introduction 5

6 Introduction

2 Installation

This chapter covers the steps required to install your U-336R/RE
modem into a ZyXEL RS-1612 rack system. A separate
comprehensive manual containing rack system information is
included with your modem rack chassis.

U-336R/RE Modem Card

The U-336R front panel consists of fifteen LED indicators and two
switches. The U-336RE front panel consists of fourteen LED
indicators and two switches. The LEDs on the front panel, display
the current status and configuration of the modem. Refer to the
following table for details on the LED status indicators and their
meaning.

LED Name ON Blinking

PWR Power Indicator The modem is on

and operational.

TST Test Indicator The modem is in test

mode.

V34 V.34 Mode

Indicator

The modem is
operating in V.34
mode.

The modem is
in
Handshaking
state.

Installation 7

LED Name ON Blinking

TXD Transmit

Indicator

RXD Receive

Indicator

CD Carrier Detect The modem senses a

DTR Data Terminal

Ready

DSR Data Set Ready The modem is ready

RTS Request to Send The DTE requests

CTS Clear to Send The modem is able

OH Off Hook

Indicator

ORG Originate Mode

Indicator

RI Ring Indicator Modem is in Auto-

The DTE is sending
data to modem for
transmission.
The modem is
sending received
data to the DTE.

valid data carrier on
the line.
The attached
computer is ready to
send or receive data.

to send or receive
data.

to send data for
transmission.

to accept data for
transmission.
The modem is in
Data Mode or Off
Hook.
Modem is in
Originate Mode.

Answer mode.

Modem
detected an
incoming call.

8 Installation

LED Name ON Blinking

SQ Signal Quality Modem senses a

good quality signal.

Modem
senses
marginal
signal quality.

The following LED is for the U-336R only:

LED Name ON Blinking

LL Leased Line

Mode Indicator

Modem is in Leased
Line Mode.

There are two toggle switches on the U-336R/RE front
panel.VOICE/DATA Toggles the modem on-line (off-hook,
DATA) or off-line (on-hook, VOICE mode, the telephone set is
connected to the line). ANS/ORG switches the modem between
ANSWER and ORIGINATE modes when the modem goes off
hook.

OONOTE: THE ANS/ORG SWITCH ONLY DETERMINES MODEM ON-LINE MODES WHEN THE

MODEM IS SET TO OFF-HOOK MANUALLY. IF ATD OR ATA COMMANDS TAKE THE
MODEM OFF HOOK, THOSE COMMANDS WILL DETERMINE THE OPERATING MODE
FOR THE MODEM TOO.

Required Steps for U-336R/RE Installation

Setting up the rack system consists of plugging in modem cards,
connecting phone lines, connecting to computers, and connecting
power. Refer to your rack system User’s Guide for details on
setting up the rack.

Installation 9

Installing the modem card

The rack system in which you will install your modem has sixteen
available modem slots. You may use any slot for a card without
regard to the slot number or sequence. To install a card:

1. Hold the modem card by the front and slide it into an available

slot.

2. Push the card gently but firmly until it seats.

3. Screw the modem card holding screws into place to secure the

card in its slot.

OONOTE: THE MODEM CARD WILL NOT SEAT AND THE HOLDING SCREWS WILL NOT

TIGHTEN IF YOU INSTALL THE MODEM CARD UPSIDE DOWN.

Connect to phone lines

Sixteen terminal blocks correspond to the sixteen modem card slots
in the rack. Each offers you flexibility with respect to the types of
phone lines you may be using. Each terminal block has three
sections:

• U-336RE Section 1 (terminals 1 & 2) For standard telephone

set connection.

10 Installation

• U-336R Section 1 (terminals 1 & 2) For standard telephone

set connection.

• U-336RE Section 2 (terminals 3 & 4) For dial-up line and 2W

leased line connection.

• U-336R Section 2 (terminals 3 & 4) For dial-up line.

• U-336RE Section 3 (terminals 5 ,6 ,7 & 8) Not used.

• U-336R Section 3 (terminals 5 ,6 ,7 & 8) For leased line

connection.

Connect to Computers

Each modem slot has a corresponding 25-pin RS-232 female
connector on the rear panel. Connect a cable from the desired
computer to the RS-232 connector for the desired modem.

Hooking Up Power

Connecting power should be the last thing you do before using the
rack. To connect power follow the instructions below:

1. Plug one end of the power cord to the socket on the back panel.

2. Plug the other end to a properly rated power source.

3. Switch the power source selector to AC or DC according to the

type of power supply(s) you are using.

4. Make sure all other hardware installations are complete.

5. Unscrew the front panel and turn on one or both power

supply(s).

6. Replace the front panel.

7. Turn on the master power.

Fax/Modem Communication Software Installation

After completing installation of your modem use the following
procedures to verify your modem connections:

1. Install and load your communications software. If you need

assistance, refer to the manual that came with the software.

2. If your communications software requires you to select a

modem, and the your modem is not one of the choices, you can
either check our web site for the driver or select the ZyXEL U-

Installation 11

1496 modem. In many cases, the commands for these modems
are identical.

Select the following communication settings:

Setting Value

Baud rate 57,600bps
Data bits 8
Parity None
Stop bits 1
Flow control Hardware
Initialization string AT&F
Port COMn*

OONOTE: WHEN SPECIFYING A PORT ASSIGNMENT, THE ‘N’ INDICATES THE COMPUTER

SERIAL PORT TO WHICH YOUR MODEM IS ATTACHED. FOR EXAMPLE, IF YOUR
MODEM IS CONNECTED TO SERIAL PORT 2, YOU WOULD SELECT COM2.

3. Place your communications software in terminal or direct
connect mode (your communications software manual will
explain how).

4. Look at the modem’s front panel and verify the DTR LED is
ON. If this LED is OFF, your communications software is not
addressing your modem at the correct COM port. Make sure
your software is set up for the same COM port to which your
modem is connected.

12 Installation

5. Type AT and press the Enter key. You should see the AT
characters you typed, followed by an OK result code. If you do
not see an OK result code, turn the modem off and on, then
repeat this step. If you still cannot see the characters, refer to
Chapter 0 for troubleshooting suggestions.

6. Type ATDT number and press Enter, where number is your
modem’s telephone number. You should see a BUSY result
code. If you do not see a BUSY result code, refer to Chapter

10 for troubleshooting suggestions.

Installation 13

14 Installation

3 Basic Modem Operation

This chapter covers the basic commands and techniques involved in
modem operation. In many cases, this is the only information you
will need in order to get up and running with communication
software, and to start making connections with your modem.

Understanding AT Commands

The U-336R/RE communicates asynchronously with computers
using AT commands. AT commands are used to configure and
control your modem. Commands are usually sent to the modem by
way of communication software, but can also be entered manually
by the user with the computer keyboard.

Command statements must be written in a specific form in order for
your modem to recognize them. A command statement always
begins with the letters AT or at. It is then followed by one or more
commands and the <Enter> key.

AT commands can only be issued when your modem is in
“command mode” or “off-line.”

Once your modem has established a connection with another
modem it is said to be “on-line” or in “data mode.” In this mode,
the characters sent to your modem by your computer are
transmitted to the remote modem rather than being interpreted by
your modem as commands.

Using the Windows 95 Hyper Terminal Program

In order to issue an AT command statement, you first need to run a
communication program such as Microsoft Windows “Hyper

Basic Modem Operation 15

Terminal” program. This program provides a simple method to
manually enter AT commands so you can do such things as
“customize” the settings of your modem, or store commonly used
phone numbers.

Once your modem is connected to your computer’s serial port and
telephone line, open the Windows 95 “Accessories” program
group, and open the Hyper Terminal Program.

The program will prompt you for a name and Icon to use for your
new connection. Type the name Test Connection and press
<Enter>.

Next, you will be prompted for country information, area code and
phone number, and the device used to make the connection. For
this test purpose, do not enter a phone number; simply choose the
COM port your modem is connected to from the “Connect Using”
list. Click “OK” when finished.

The next window sets the COM port settings. The settings used for
your modem should be as follows:

Bits per second: 57600
Data bits: 8
Parity: None
Stop bits: 1
Flow Control: Hardware

Click “OK” when finished. After you have done this, save your new
connection by selecting “Save” from the “File” menu and click
“OK.” A new connection icon will be added to your Hyper
Terminal folder.

You are now ready to start entering AT commands.
In the terminal window, type:

AT<Enter>

16 Basic Modem Operation

Your modem responds:

OK

This confirms that the modem and your computer are
communicating correctly.

To test the telephone line connection issue the manual answer
command.

Type:

ATA<Enter>

Your modem will pick up the phone line, and try to communicate.
Normally, this command is only used to answer an incoming call
made from another modem, thus the high pitched tone you will hear
from the speaker. To abort the operation, press any key, or select
“Disconnect” from the “Call” menu.

Dialing and Answering Techniques

Depending on what communications software you use to make
modem connections, you may not have as much control of how the
modem dials the telephone number. This section shows some useful
examples of the AT commands used for dialing and answering
operations. The command characters specific to each function are
shown in bold type.

Dialing using the ATD Command

Touch Tone Dialing: ATDT 555 1212
Pulse Dialing: ATDP 555 1212
Tone and Pulse Dialing: ATDP 555 1212 WT 24
Dialing Through a PBX: ATDT 9 W 555 1212

OONOTE: THE 'W' IN THE DIAL STRING WILL CAUSE THE MODEM TO WAIT FOR A SECOND

DIAL TONE BEFORE IT CONTINUES TO DIAL.

Basic Modem Operation 17

Pausing During Dialing: ATDT 9,,555 1212

OONOTE: THE PAUSE TIME FOR EACH COMMA IS DEFINED BY S REGISTER S8. DEFAULT IS

2 SECONDS PER COMMA.

Dialing Without Waiting for Dial Tone: ATX0D, 555 1212
Originating a call using an Answer Tone: ATDT 555 1212,,,,,,R
Redialing the Last Number Called: ATDL
Waiting for Five Seconds of Silence: ATDT 800 555 1212 @

123456,1 714 555 1212

Transferring a Call (using flash hook): ATDT! 2468

Auto-Answer and Hook Controls

Enabling Auto-Answer: ATS0=n

OONOTE: IN THIS EXAMPLE, N IS A NUMBER FROM 1 TO 255 THAT CORRESPONDS TO THE

NUMBER OF RINGS AFTER WHICH YOUR MODEM ANSWERS AN INCOMING CALL.

Disabling Auto-Answer: ATS0=0
Manually Answering a Call: ATA
Take modem off-hook: ATH1
Hang up modem (on-hook): ATH0
Manually Disconnecting a Call: +++ATH

Making Your First Connection

For this example, we will use the connection you created in the
Hyper Terminal program to dial the ZyXEL BBS. If you are using a
different terminal program, run the program according to the
instructions provided with it.

18 Basic Modem Operation

Start the terminal program by double-clicking the Test Connection
icon. When the terminal window appears, enter the dial command
with ZyXEL’s BBS as the phone number.

Type:

ATDT17146930762<enter> (Omit the ‘1714’ if
you are in this area code)

The modem will go off-hook, dial the number, and after a few
seconds of negotiation tones you should be connected to our BBS.

You will receive a login message asking for your name. For the
purposes of this example you need not continue. Just click the
“disconnect” icon on the toolbar.

Quick Tips when issuing AT Commands

• The ENTER or RETURN key must be pressed to execute a
command.

• Multiple AT commands can be combined into one line. For
example, AT&D2 and AT&N0 can be combined into one line
AT&D2&N0.

• Your modem processes commands from left to right. The AT
command that appears to the right might over-write the
command to the left if they are trying to accomplish tasks or set
modes that cannot coexist.

• If you see duplicated characters for each one you type, your
modem and software both have their “echo” feature turned on.
The modem command echo state is switched Off using ATE0
and On using ATE1 (default). To eliminate the double
characters, turn off the software’s command echo rather than
using the ATE0 command. If you see no characters in your

Basic Modem Operation 19

terminal window when you type, the modem’s echo setting is
probably set to off. In this case, issue the ATE1 command.

• When a command is successfully issued and accepted, a modem
responds with a “Result Code.” Your modem supports both
“verbose” result codes (i.e. “OK”), and “numerical” result
codes (i.e. “0"). You can use the ATV command to set it one
way or the other as follows:

Command Description

ATV0 Select numerical result code.
ATV1 Select verbose result code.

There are a few basic commands that do not require the “AT”
command prefix. These are as follows.

Command Description

A/ Repeats the last issued AT command once.
A> Repeats the last issued AT command once, or

re-dials the last dialed number up to 9 times
until a key is pressed or a connection is made.

<any key> Terminates the current connection attempt, if

pressed while modem is handshaking.

+++ Escape code sequence. Entered while the

modem is in Data Mode. Returns modem to
Command Mode.

Your modem supports several groups of AT commands:

AT Command Set/Type Example

Basic AT (Hayes compatible) ATB0
Basic AT$ (on line help) AT$
Extended AT& commands AT&N0
Extended AT* commands AT*I1
Fax AT+ commands AT+FCLASS=2

20 Basic Modem Operation

AT Command Set/Type Example

S-Register command ATS0=1
S-Register bit-mapped command (set S-

Register bit 1 equal to 1)

ATS13.1=1

S-Register inquiry command ATS0? Or ATS13.1?

You may browse the lists of available commands for each command
set by using the on-line help commands: AT$, AT*$, AT&$, and
ATS$. Further detail on AT commands will be covered in the
chapters that pertain to their use.

Modem Result Codes

When you execute or try to execute an AT command, your modem
sends a result code to let you know whether the command was
executed. An OK result code means the AT command you sent was
executed. If you receive an ERROR code, it means the command
was invalid.

Your modem also provides result codes that show:

• Whether or not a Dial Tone was detected when the modem
originated a call.

• If a busy signal was detected when the modem originated a call.

• If a remote telephone ring was detected when dialing.

• The speed, protocol, and error control/data compression

method used.

• If your modem has detected an incoming ring.

Result codes can originate from any of eight result code sets. The
ATXn command lets you choose which set of result codes your

Basic Modem Operation 21

modem uses. By default, your modem uses result codes equivalent
to the ATX5 command.

The result code options will be covered more thoroughly in later
chapters.

Viewing S Register Values

Status registers (or "S-registers") contain values that determine the
modem’s operating characteristics. Whenever you send an AT
command to your modem, you are actually changing the value of an
S-register.

You can use the Sr? command to view the value of S-register ‘r’.
For example, to view the value of S-register S0, which controls
auto-answering, type ATS0? and press Enter. The modem responds
with a three-digit character showing the value of this register,
followed by OK. A value of 002, for example, means your modem
will auto-answer incoming calls after the second ring.

Some S-registers are bit mapped. For these registers, you can use
the Sr.b? command to read their values.

For example, to read the value of S-register S35, bit 7, type
ATS35.7? and press Enter. The modem responds with an
appropriate value, followed by OK.

Changing S Register Values

You can use the ATS0=n command to change the value of an S­register.

For example, to have your modem auto-answer an incoming call
after two rings, set S-register 0 to 2. Be sure the n value is between
1 and 255. If n is set to 0, your modem will not answer incoming
calls.

22 Basic Modem Operation

Non-Volatile Memory

Your modem has an amount of memory set aside for storing user
information such as frequently used phone numbers and default
command settings. The latter is particularly useful when using your
modem to call a variety of different locations that require different
settings. For this reason, your modem provides a number of user
“Profiles” that can be accessed through simple AT commands. This
section covers the topics of storing phone numbers, and saving
default settings in the power-on profile.

Storing Phone Numbers

The AT command to store a phone number is in the format
AT&Zs=n.

The ‘s’ is a number from 0 to 49 that represents the location in
memory that the phone number is to be stored, and the ‘n’ is the
phone number itself.

Example: To store the number ‘1-816-555-1212’ in memory
location ‘2’, type:

AT&Z2=17145551212<Enter>

You can store up to 50 telephone numbers.

Dialing Stored Phone Numbers

The AT command syntax used to dial a stored number is ATDS=n.
The ‘n’ is the memory location of the stored number you want to

dial.

OONOTE: AS A GENERAL RULE, WHEN A LETTER IN AN AT COMMAND DEFINITION IS SHOWN

IN ITALIC TYPE, THE LETTER IS NOT TO BE ENTERED AS PART OF THE COMMAND,
BUT RATHER IS REPRESENTATIVE OF A NUMBER OR STRING EXPECTED AS INPUT.

FOR EXAMPLE: THE LETTER ‘S’ IN THE ATDS=N COMMAND IS ACTUALLY TYPED,

UNLIKE THE ‘S’ IN THE AT&ZS=N COMMAND WHICH REPRESENTS A NUMBER.

Basic Modem Operation 23

Saving Settings and User Profiles

There are some cases where you may wish to save the settings you
have made as the default settings that are recalled when your
modem is powered up. The AT&WZ command selects the current
settings as the power-on profile.

There are four profiles that can be changed by the user, and one
factory default profile. The following table lists the syntax for the
commands involved in storing, recalling, and viewing profile
settings.

AT&Vn Views the settings in profile (n-1); n=0 to 5; n=0

views current settings.
AT&Wn Stores the current settings in user profile ‘n’; n=0 to 3
ATZn Resets the current settings with the settings in profile

‘n’, n=0 to 4.

Profiles 0 to 3: User profiles.
Profile 4: Factory default profile.

Helpful Hints for PC Computers

Most PCs are equipped with more than one serial port. Standard
cables are readily available from many suppliers. Usually, serial
ports are manufactured in two forms, either with a 25-pin male jack
or a 9-pin male jack. For high speed serial connections at

230.4Kbps or 460.8Kbps, use a low-capacitance cable. Also, keep
the cable as short as possible.

The serial port is driven by interrupts. Every interrupt needs a
certain amount of overhead processing time. Too many interrupts
reduce the computer's efficiency. The UART 16450 is very
commonly used in serial port devices. For every character (byte)
received, it generates an interrupt. If your hardware allows it and if

24 Basic Modem Operation

your software supports it, replace the 16450 UART with a 16550
model. This newer chip has an internal buffer and generates an
interrupt for up to every 16 characters (several trigger levels are
available). With this UART installed, you may drive your serial port
at 57600 bps and above.

While data is written from the transfer-buffer to your hard-disk,
characters may be lost at the serial port. This is due to the fact that
disk-access interrupts have a higher priority than serial port
interrupts. If you are running at a high serial speed, e.g. 230.4Kbps
or 460.8Kbps, on your PC, be sure to enable the disk cache by
including SMARTDRV execution in your AUTOEXEC batch file.

Default Modem Settings for PC’s

Your modem’s factory settings are configured for operation with
PC type computers and communication software. In most cases, no
additional settings will be required. The following are some of the
default settings that are used for operation with PC computers and
software.

AT Command Description

E1 Echoes command characters.
&C1 Carrier detect follows remote carrier.
&D2 Modem disconnects on DTR on-to-off transition.
&K4 Use both V.42 and MNP 4 error correction, and

use both V.42bis and MNP 5 data compression.

&N0 Modem negotiates highest possible connection

speed.

ZyXEL Serial/Parallel I/O Card

For high-speed PC to modem communication, ZyXEL produces a
special I/O adapter card. This card includes a serial port and a
parallel port, each with special features, particularly when working
with a ZyXEL modem, for example:

Basic Modem Operation 25

The serial port is 16550-compatible for most communication
software usage. It has a speed of up to 460.8Kbps and data loss
errors will not occur when working with a ZyXEL modem's serial
port. This solves high-speed communication problems in Windows
and other multi-tasking systems. The serial port has a 32-byte
transmission and a 32-byte receival FIFO to increase
communication program efficiency.

Helpful Hints for Macintosh Computers

Special AT Command Settings for Macintosh

For operation with Macintosh computers, you may use the factory
default settings with one exception. You must set the modem to
ignore the DTR signal as follows:

Type:

AT&D0<enter> (set modem to ignore DTR)

AT&WZ<enter> (saves the settings to power-
up profile)

Macintosh Serial Port

When you connect your modem to a Macintosh computer, make
sure the cable is a hardware handshaking type. These cables are
readily available. Macintosh Lisa model 128 and 512 don't have
hardware handshaking. The serial port on these (very outdated)
models is provided as a 9-pin connector similar to that of a PC. The
serial port on all other Macintosh models is a Mini-8.

Mac Software Tips

All terminal programs which make use of the hardware handshaking
feature can be used on the Apple Macintosh. Such programs are

26 Basic Modem Operation

readily available as PD, shareware or commercial software. One of
the most powerful shareware programs available is ZTerm.

Fewer programs are available to make use of the ZyXEL's fax
features. One program which has found wide acceptance is FaxSTF
which can be installed like a printer driver allowing you to send
faxes from almost any program which runs on your Macintosh. At
the same time it allows automatic fax receiving. This program
includes powerful line manager software which makes sure fax
software does not interfere with other programs using the serial
ports. If the modem is turned off when you start your Macintosh
with the line manager activated, the computer may seem to freeze
for a few minutes. During this time the line manager software tries
to locate and to set up the modem. Turn on your modem before
you start your Macintosh to avoid this delay.

MaxFax is another fax software for Macintosh computers.
Drivers are available which allow use of the serial ports at speeds

up to 230.4 Kbps. These drivers are currently available for Power
Macs and AV Macs only.

Helpful Hints for UNIX-Based Computers

Serial Cable

Consult the documentation that came with your workstation to find
the part number of, or information on, how to make a serial cable
for your workstation. The cable should be a hardware-handshaking
type. Refer to Chapter 12 Terminal Pinouts for a complete list of
signals provided for the modem’s serial port.

Basic Modem Settings for UNIX

Unix environments usually don’t like modem responses or echoing
of commands. Therefore you should set ATE0Q1.

Basic Modem Operation 27

Depending on your Unix setup, the cable and software used, you
may have to disable carrier detection using AT&C0.

Unix Software Tips

In order to use your ZyXEL modem from a terminal screen or an
X-Windows application, you need a program such as Minicom or
Seyon.

If you wish to make use of your ZyXEL modem's special features,
special gettys such as mgetty or vgetty are needed. These programs
are avaiable from several ftp-sites. Some archives also contain
source files.

You should suppress the modem's result code to(ATQ1) because
some applications may be confused by them.

28 Basic Modem Operation

4 Synchronous Mode Operation

This chapter introduces you to the use of the U-336R/RE for
synchronous operation. The modem can be used as a synchronous
modem when it is connected to a synchronous computer or
terminal. It is of course necessary to make sure that the remote
modem and system are also set to synchronous mode. Synchronous
operation applies to all of the non-FSK modes the modem is
supplied with. Before synchronous transfers are started, some initial
settings should be made.

V.25bis Command Set

To enable V.25bis commands use the AT*I1 command.
For synchronous applications, the modem is permanently set in

normal situations for use with one application. Save the desired
settings in the power-on profile, and the modem will be initialized
to synchronous mode, (&M3) with V.25bis command enabled,
(*I1) when powered on.

A special command RST is provided to get the modem back to
asynchronous AT command mode from V.25bis mode. You can
enter this RST command in either synchronous or asynchronous
V.25bis mode.

Synchronous Mode Operation 29

Syntax Command with

Parameters*

CRN CRN <dialstring>** Call request with number

CRS CRS n Call request with number from

PRN PRN n; <number> Saves <number> to address n

RLN RLN*** Requests list of all stored

DIC DIC Ignores incoming call.
CIC CIC Accepts incoming call.
CFI CFI XX Call failure indication:

INC INC Incoming call.
VAL VAL Valid.
INV INV Invalid.
LSN LSN n; <number> List of stored numbers.

RST RST Changes to the asynchronous

Description

provided.

memory, 0 # n # 49;
n is the memory location.

(0 # n #49).

numbers.

ET Engaged Tone.
NS Number is not stored.
RT RING Tone.
AB Abort Call.
NT Answer Tone is not
detected.

(Response to RLN)

AT command mode.

Clock Options

Synchronous data must be transmitted and received with a common
timing clock. This timing clockis used to transmit data from the
DTE to the modem which modulates the data according to this
clock. The receiving modem recovers the clock and data from the

30 Synchronous Mode Operation

carrier and sends the data to the receiving DTE along with the
clock. There are three types of transmission synchronous clock
sources to choose from:

1. The internal clock is the one that suits most applications and is

2. The slave clock is used when in remote digital loopback mode.

3. The external clock is a signal generated by the sending DTE.

INTERNAL AT&X0 The modem provides the clock and

EXTERNAL AT&X1 The DTE provides the clock and

SLAVE AT&X2 Recovered receiver clock serves as

RTS Options

the default; in this case, the clock signal is generated by the
sending modem.

sends it to the DTE. Adaptive rate
can be used. (Default)

sends it to the modem. Must use
auto-retrain, cannot use adaptive rate.

transmission clock.

There are two RTS options. The choice depends on application and
host/terminal requirements. In asynchronous mode RTS is used as a
hardware flow control signal.

IGNORED AT&R1 RTS is ignored; always assumed

to be ON. (Default)
CTS TRACKS
RTS

AT&R0 Delay before CTS responds to

RTS's change. The delay is set in

the S26 register.

Synchronous Mode Operation 31

Command State Options

For synchronous data communication, there are two options you
can choose from to define how the modem will operate in the
command state.

SYNC
DATA

SYNC AT&M3 The modem accepts synchronous

AT&M1 The modem accepts asynchronous

commands in command state, but
exchanges data synchronously in data
state.

command (V.25bis) and exchanges
data synchronously with a remote
modem.

Dialing from Synchronous Mode

1. Dial from the terminal using asynchronous commands: Set

&M1 and use asynchronous AT commands to dial the number.

Once the modem is connected, the modem will enter
synchronous operation.

2. Dial through the computer using V.25bis commands: Some

communication software packages on synchronous computers
can dial using V.25bis synchronous commands. In this case, set
&M3 and *I1 and the modem will accept V.25bis commands
and make a synchronous connection.

3. Using DTR to dial a stored number in synchronous mode:

Store the telephone number by the asynchronous command
&Zn=. Use the DEFAULT DIAL parameter menu or *Dn
command to select the default dial pointer. Set &D1 and either
&M1 or &M3, then raise DTR from your terminal or
communication software. The modem will dial the default
stored number. After the modem is connected, the modem will
enter synchronous operation.

32 Synchronous Mode Operation

4. Manual dial: Set the modem to synchronous mode (&M1 or

&M3), then dial a number from a telephone set. When you hear

the answer tone, type ATD (if &M1 is set). The modem will go
into synchronous operation after connection.

Answering from Synchronous Mode

Auto-Answer

Set the modem to synchronous mode. Set the S-register S0 to equal
the number of rings before auto-answer occurs. Set it from the
terminal (if &M1 is set) using the asynchronous AT command, or
select the STATUS REGISTER menu to change the S0 value.

Manual Answer

Type ATA from the terminal (if &M1 is set).

Synchronous Mode Operation 33

34 Synchronous Mode Operation

5 Leased Line Operation

A leased line is a permanent telephone line connection between two
fixed points. It can be dedicated copper wires or a leased telephone
circuit from the telephone company. Four-wire leased lines use one
pair of wires to transmit data and a second pair to receive. Two­wire leased lines transmit and receive on the same pair of wires.
The U-336R supports 2 and 4-wire leased lines while the U-336RE
supports 2-wire leased lines.

Connecting to a Leased Line

Your modem default line is a dial-up type (DL) which includes a
separate leased-line jack. The leased line must be connected to the
jack labeled LEASED LINE (located at the rear of the modem).
You can set your modem for leased-line operation by typing
commands from the terminal or by selecting it from the front panel.
The leased-line phone jack pin assignments are shown in Chapter
12 Terminal Pinouts.

Line Type Setting

AT-Command Description

AT&L1 The modem is connected to a 2-wire leased line;

the line plug should be plugged into the jack
assigned DIALUP for RE model or leased line
for R model on the rear panel.

AT&L2 The modem is connected to a 4-wire leased line.

Plug the line into the LEASED LINE jack.

Leased Line Operation 35

Power Level Setting

Your modem’s leased-line mode transmission power level can be
adjusted from 0 dBm to -27 dBm in 1 dBm increments.

AT-Command Description

AT*P0
. . .
AT*P15

The default is -9dBm. The adjustable range is
from 0 to -15dBm, effective in leased-line
operation only. If bit 3 of S35 is 8set, this range
will change to -12 to -27dBm.

Leased Line Handshaking

In a typical dial-up connection, the originating modem dials the
number and waits for the answering modem's carrier signal. The
answering modem can be commanded to either answer the call
immediately, or after a specified number of rings.

In a leased-line connection, the communication circuit between two
modems is always present. Dialing and waiting for rings does not
occur in this situation. If these two modems want to establish a data
link, one must be designated as the originator and the other as the
answerer. You can set this manually or automatically.

Manual Connect

Set the modem to leased-line mode. Type the asynchronous
command ATD to the originating modem and ATA to the
answering, or press O on the RS1612 control panel for originating
mode and then press A for answer mode. Use AT*Mn or set

S14b0 to select originate or answer mode.

Auto Handshake

If you want handshaking to occur automatically upon power-up,
you have to save the leased-line configuration to the power-on
profile. Remember to set the handshake mode before you save the

36 Leased Line Operation

configuration. Be sure that one modem is set to originate mode and
the other to answer mode.

AT-Command Description

AT*M0 When operating over a leased line, modem will

handshake in originate mode. (Default)

AT*M1 When operating over a leased line, modem will

handshake in answer mode.

Leased-Line Dial Backup

When a leased-line connection fails, the following actions may be
taken by the modem:

• Reattempt to connect on the leased line indefinitely if the dial

backup option is disabled.

• If the dial backup is enabled, the originating modem attempts to

dial a pre-stored telephone number to backup the connection;
the answering modem will reattempt to connect to the leased
line and monitor the dial-up line for rings. Incoming dial-backup
calls will be answered.

Dial Backup

The dial backup option can be set by issuing an asynchronous AT
command from the terminal, or by using the RS-1612 LCD control
panel.

AT-Command Description

AT*B0 Leased-line dial backup disabled (Default).
AT*B1-50 When the leased-line cannot continue operation,

the originate mode modem will automatically
dial the number stored in the memory address
selected. The answer mode modem will monitor
the dial-up line for rings.

Leased Line Operation 37

The originating modem will try to dial the number up to nine times
or until a 3-minute time-out is activated. If the dial backup attempt
fails, the originating modem will go back to try the leased line
connection. If this fails, it will try the dial-up line again.

It will try these two alternatives indefinitely. If the dial backup
attempt succeeds, the value of S-register S34 determines the
interval of the dial backup connection before going back to check
the leased line.

AT-Command Description

ATS34=0 The dial backup line continues to be used

indefinitely.

ATS34=n;
(1≤ n ≤ 255;
default:30)

Retries leased line after n minutes. If the leased
line has still not been recovered, the modem will
continue to use the dial backup line.

Aborting from Leased-Line Operation

If the leased line has not been connected, pressing any key on the
RS-1612 LCD control panel will abort the attempt to connect to
the leased line. If dial backup is enabled, backup action will be
taken. Pressing any key again will abort the backup action and
revert to the IDLE SCREEN display.

Terminating a Leased Line Connection

Disconnecting the leased line manually will force your modem to
switch to the IDLE SCREEN. Either going on-line manually or, if
you have set the leased line as the power-on default, turning the
power OFF and ON, will make the modem try the leased line again.

38 Leased Line Operation

6 Special Functions

This chapter describes special features of the U-336R/RE, and
offers instructions on how each is used.

Security Functions

Your modem provides security that prevents unauthorized users
from making connections. Two types of security functions are
provided.

• Type 1 security is used when the remote modem is also a

ZyXEL modem.

• Type 2 security is used when the remote modem is any other

brand.

The type 1 connection, the dial-in remote modem will send in its
supervisor password for checking at the initial connection , and the
local modem will check this password against its pre-stored
acceptable password list.

The type 2 connection, the remote terminal will be prompted to
enter the password at the initial connection and the local modem
will do the password checking.

Levels of Security

Two levels of security are provided:

Special Functions 39

• With level 1 security, the local modem will maintain the

connection if the password is OK, otherwise the line
disconnected.

• With level 2 security, redial the phone number corresponding

to the dial-in password. The line simply disconnects if the
password does not match.

User Passwords

Fifty user passwords may be defined. The corresponding 50 dial­back numbers are the modem’s 50 stored phone numbers. Any
character (ASCII 0-127) can be used in the password, the
maximum password length is 8 characters.

Security functions are only accessible through AT commands in
terminal mode. Any access attempt will result in the modem’s
prompting the user to enter the supervisor password. The attempt
will be rejected if the entered password is not correct. The default
supervisor password is ZyXEL when the modem is shipped from
the factory. This supervisor password is also the password sent for
automatic password checking in a type 1 connection. To modify the
supervisor password, use AT*HS.

You will be asked for the original password and a new password
and then to re-enter the new password for verification. For
example:

Password: (Enter supervisor password)
********
Password: (Enter new supervisor password)
********

The command AT*V will list the 50 user passwords and the
supervisor password on the screen for viewing. Again, you will be
prompted to enter the supervisor password first.

40 Special Functions

The following commands will enable
different types and Verify: (Enter the new
supervisor password again)

********
OK

The command AT*Hn will modify the nth user password. You will
be prompted to enter the supervisor password first and then be
prompted to enter the nth user password.

Levels of security:

Command Function

*G0 Disable security function.
*G1 Enable type 1 and level 1 security, with

password check.

*G2 Enable type 1 and level 2 security, with

password check and callback.

*G3 Enable type 2 and level 1 security, with

password check.

*G4 Enable type 2 and level 2 security, with

password check and callback.

*G5 Enable type 2 and level 2 security, with

password check and callback, remote site
enters the callback number.

OONOTE: BEFORE THE SECURITY TYPE OR LEVEL CAN BE CHANGED, THE MODEM

REQUIRES THE SUPERVISOR PASSWORD.

For type 2 security, the remote site will be prompted to enter the
user password. A maximum of 3 tries in 40 seconds is allowed. If a
correct password is not entered within this time limit the line will be
disconnected. If the remote site is to enter the callback number it
will be prompted to do so.

Special Functions 41

Remote Configuration

Remote configuration for your modem is provided as a profile by

profile batch mode. When on-line, the remote modem’s current
configuration or one of its profiles can be read into one of the local
modem’s user profiles. This profile is modified locally and the line
can be disconnected during this time.

Local profile modification is done by loading this profile as the
active settings and then modifying and saving the active settings
back to the profile. Then the connection is reestablished and the
profile transmitted to the remote modem.

Reading a remote profile b into a local profile a is achieved with the
command:

AT*Rab

a=0-3 Local user profile number
b=0-3 Remote user profile number
b=4 Remote active configuration
b=5 Remote factory default

Return the modems to on-line status again. The local modem can
upload (write) its profile to the remote modem’s profile and have
the remote modem reset from the new profile. This is done with the
command:

AT*Wab

a=0-3 Local user profile number
a=4 Local active configuration
a=5 Local factory default
b=0-3 Remote user profile number

42 Special Functions

The remote profile read and write commands - *Rab and *Wab ­only work in the on-line condition. The connection speed and mode
do not matter. The remote modem must be set to accept remote
configuration by executing the AT*F1 command. The AT*F0
command will set the modem up to deny remote configuration
requests. Because the modem uses the remote digital loopback
mode to request remote configuration information, the remote
digital loopback request must also be granted (AT&T4) on the
remote modem to accept the remote configuration request.

Batch mode remote configuration is a convenient feature allowing
you to pre-configure a remote modem in one of the local modem’s
user profiles and send it to the remote modem in one action. It is
particularly useful when there are many remote modems and a set
of standard configurations is available so you can store them into
user profiles. You just need to configure the remote modem into
one of the standard configurations by activating the remote
configuration once.

Caller Number Delivery (Caller ID)

Caller Number Delivery (CND), commonly called Caller ID, is a
new kind of phone service that may be offered by your local phone
company. Check your phone company for availability. You must
subscribe to it and usually pay an additional monthly service charge
for this service.

With CND service, the phone company’s central office will send the
coded caller information to the called station. This information is
sent once between the first and second rings. Your modem can
decode this caller information and present it to the connected
computer/terminal during the second ring period as part of the call
progress ring message. The modem will also report the Caller ID
information if asked by the command AT*T.

Special Functions 43

There are two kinds of caller information message formats sent by
the phone company:

• One is the single message format which includes date, time, and

caller ID.

• The other is the multiple message format which also includes

the caller name as registered with the phone company.

The command ATS40.2=n is used to enable (n=1) or disable (n=0)
the Caller ID detection function. The default is disabled. Enable it
only when you have this service and want to enable its detection.

OONOTE: THE CALLER ID MESSAGE MAY CAUSE SOME COMMUNICATION SOFTWARE TO

BECOME CONFUSED. IF YOU PLAN TO USE THE CALLER ID FEATURE, BE SURE
YOU ARE USING SOFTWARE THAT SUPPORTS IT (SUCH AS ZFAX).

In single message format, the modem will send a ring message to
the terminal as follows:

RING
TIME: <MM-DD hh:mm>
CALLER NUMBER: <CALLER_ID> or CALLER

NAME:<CALLER_NM>
RING

MM is the two-digit month message, DD is the two-digit date
message, hh is the hour and mm is the minute of the time, and
CALLER_ID is the phone number of the caller or CALLER_NM
his/her name.

The following is an example of a caller ID message as it might
appear on your screen:

RING
TIME: 04-28 12:30
CALLER NUMBER: 7135551414 or CALLER NAME:

44 Special Functions

Brent Harper
RING

In the multiple message format, if the caller’s number and name are
available, the ring message will display both:

RING
TIME: MM-DD hh:mm
CALLER NUMBER: <Caller_ID>
CALLER NAME: <Caller_Name>
RING

Here is an example:

RING
TIME: 04-28 12:30
CALLER NUMBER: 7135551414
CALLER NAME: Jordan Chu
RING

If the caller number and name are not available, the ring message
will appear as follows:

RING
TIME: 04-28 12:30
REASON FOR NO NUMBER: OUT_OF_AREA
REASON FOR NO NAME: PRIVACY
RING

The last CND message that the modem received can be displayed
by using the AT*T command.

Setting S48.0=1 will cause the modem to report CND information
in its ASCII coded hexadecimal raw data format. The DTE
software is responsible for explaining the data.

Special Functions 45

OONOTE: PLEASE REFER TO THE BELLCORE TECHNICAL ADVISORY DOCUMENT TR-NWT-

000030 FOR THE EXACT DATA FORMAT. THE ABOVE CALLER ID SCHEME

APPLIES TO THE NORTH AMERICA ONLY. DIFFERENT COUNTRIES MAY EMPLOY
DIFFERENT CALLER ID SCHEMES, MAKE SURE THE SCHEME USED IN YOUR
COUNTRY IS SUPPORTED BEFORE USING THE CALLER ID FEATURE. FOR MOST
OTHER CALLER ID SCHEMES, ONLY THE CALLER TELEPHONE NUMBER IS
PROVIDED.

Distinctive Ring

Distinctive Ring is a phone service that may be offered by your

phone company. Check your phone company for availability. With
this service, you can have several phone numbers assigned to the
same phone line. The phone company will send a different type of
ring signal for each phone number being called. The subscriber can
distinguish which number is called by which type of ring is received.

One benefit of this feature is the ability to have three numbers on
the same line allowing you to list the three numbers for voice, data,
and fax, respectively. You can then have your fax machine answer
only the ring corresponding to the fax number and have your
modem answer only the ring corresponding to the data number. A
voice call will not be answered by either fax machine or data
modem and it will only be answered when someone picks up the
phone. You can also have the answering machine answer only the
voice ring. A more complicated use is that you can have one
number for multiple uses, such as one number for both data and fax.

A ring signal is a composition of repeated on and off states.
Different types of rings usually correspond to different
compositions of the “ON” part (cadence) of the ring. Your modem
can distinguish up to four types of ring signals and can be
commanded to answer or not answer any one of these four types of
ring signals. Following is a list of these four types of ring signals.
These are the ring types used in the USA. The difference among the

46 Special Functions

ring types is the two-second ON part of the ring signal. It
comprises a long, double short, or triple short ring.

S-register S40 bits 3-6 are used for distinctive ring control. Each
bit controls the answering of a particular ring type. Setting a bit to
“1” (on) enables answering, setting it to “0” (off) rejects the ring.
Note that the ring may still be heard even if it is not counted as an
accepted ring by the modem.

The control relationships between bits 3-6 in register S40 and the
different ring types are:

Type Bit

Ring Sequence

(on)

1 3 1.2s or 2s on; 4s off
2 4 0.8s on, 0.4s off, 0.8s on; 4s off
3 5 0.4s on, 0.2s off, 0.4s on, 0.2s off, 0.8s on; 4s

off

4 6 0.3s on, 0.2s off, 1s on, 0.2s off, 0.3s on; 4s off

OONOTE: IF ALL OF THESE BITS ARE "0" (OFF), ANY RING WITH A DURATION LONGER THAN

100 MS WILL BE ACCEPTED. USE THIS DEFAULT IF YOU DO NOT HAVE

DISTINCTIVE RING SERVICE.

If more than one type of Distinctive Ring is turned on, RING n will
be reported for an incoming ring signal where n is the ring type
number.

OONOTE: COUNTRIES OTHER THAN THE U.S. MAY HAVE DIFFERENT SPECIFICATIONS FOR

DIFFERENT RING TYPES. THE MANUFACTURER MAY APPEND OTHER SETS OF
RING TYPE SPECIFICATIONS TO SUIT EACH COUNTRY'S NEEDS.

Extended Distinctive Ring (EDR)

Extended Distinctive Ring (EDR) is a special feature designed for

single telephone line home use to receive fax or data calls without

Special Functions 47

interfering with regular voice calls. When most users install a
fax/modem at home, they won’t subscribe to an extra telephone line
for occasional fax or data calls; however, fax/data calls do come in
from time to time.

If a user lets the fax/data software application answer, voice calls
will be missed. On the other hand, if the user or an answering
machine answers, fax or data calls may either be missed or the
person who answers the call has to go through some procedure to
get this call connected to the proper application. Either way is not
desirable.

Once enabled with the proper settings, EDR can:

1. Detect the data/fax CNG tone without physically answering the

call. After a CNG tone is detected, the modem will report
RING or RING n to the application software. The software can
cause the modem to answer the call.

2. Detect several DTMF tones without physically answering the

call. The DTMF tones, once detected by the modem, will be
reported as RING or RING n to the software application.

With these two functions, your modem can be installed with an
answering machine or voice telephone set at home. In most cases,
the modem should not be set to answer regular rings, nor to report
them. Thus, the software will not instruct the modem to answer the
call when the phone rings. When a call comes in, the answering
machine will answer the phone and play a voice message. At this
moment, the modem, having detected the ring signal is gone, will
start to listen to the line for CNG tone or DTMF tones.

If the remote caller is an unattended fax machine, it will send a
CNG tone for a period of time. The modem will detect the CNG
tone and report RING to the software immediately. The software
application can then issue commands to answer the call and receive
the fax. If the remote caller is using a fax phone which does not
send out a CNG tone and is waiting for a fax answer tone in order

48 Special Functions

to press the START button, the caller can press a designated
DTMF tone, which will activate the modem to report and
subsequently be ordered to answer the fax call.

Setting Up EDR

The new EDR can be used at home where multiple phones are
installed in parallel. Once this function is enabled, the modem will
go into EDR mode after the ring disappears, and it will be able to
detect the data/fax CNG tone and DTMF tones, and report them as
different types of rings. The EDR settings are defined in S-register
S51.

S51 Bit-mapped register: (default: 0)

Bits Bin. Dec. Description

(7,6) 00 0 Disable data CNG tone detection

(default).
01 64 Report RING for data CNG tone.
10 128 Report RING 1 for data CNG tone.
11 192 Report RING 3 for data CNG tone.

(5,4) 00 0 Disable Fax-CNG tone detection (default).

01 16 Report RING for fax CNG tone.
10 32 Report RING 1 for fax CNG tone.
11 48 Report RING 2 for fax CNG tone.

(3,2) 00 0 Disable DTMF tone detection (default).

01 4 Report RING for a DTMF tone.
10 8 Report RING <DTMF> for a DTMF

tone.
11 12 Reserved

(1,0) 00 0 Disable EDR (default).

01 1 Report RING twice.
10 2 Report RING four times.
11 3 Report RING six times.

Special Functions 49

EDR detection (either CNG or DTMF tones) will be disabled once
detection occurs. However, a customer’s program might not
answer because the setting of the software may require multiple
rings to answer. S51 bits 0-1 control the number of rings that the
modem will report once the CNG or DTMF tone is detected.

The timing relationship between the Caller ID (if enabled), EDR,
and ring detection is as follows:

ring1 ring2 ring3

***--------***--------***-----------------------------­ 3sec 3s 3s 3s S7 time-out
+------+---+------+---+------+---+-------------+---­ CID/EDR RD EDR RD EDR RD EDR RD

CID=Caller ID task RD=Ring Detection task EDR=EDR task

OONOTE: DURING THE EDR PERIOD, ANY AT COMMAND WILL DISABLE THE EDR

FUNCTION.

EDR Application Example

If we use ZFAX as our fax receiving application and we don’t want
it to answer the call unless it is a fax call, the way to set it up would
be:

1. Set ZFAX to answer on 2 rings.

2. Set S51.0=1 to enable EDR and report RING twice. The

modem will not report a normal RING and ZFAX will not
answer a call unless EDR RING is reported.

3. Set S51.4=1 to enable fax CNG tone detection. It is reported as

RING.

50 Special Functions

4. Set S51.2=1 to enable DTMF tone detection. It is reported as

RING. If the remote fax machine does not generate the CNG
tone, ask a fax caller through your answering machine message
to press “*” (or any other DTMF key) if he or she wants to
send a fax.

Save the settings in a profile and reset the modem with AT&WZ.

Special Functions 51

52 Special Functions

7 Fax Operation

In the sections below, we will describe how the U336R/RE works
as a fax machine, the ITU-T T.30 fax protocol, the Class 1, 2, and

2.0 fax commands and ZyXEL extended fax AT commands. Also
covered are the status report result codes, the flow control protocol
associated with ZyXEL fax AT commands, and some specific fax
applications. The instructions for using the included
modem/fax/voice utility program are included on the software disk.
Some distributors and dealers may have included other software
with your modem. For help with such software, refer to the
software instructions.

Modem as Fax Machine

Modems can also be designed to include a fax transmitting and
receiving function similar to a fax card. Since the modem's interface
with the computer is the standard serial RS-232 interface, this
interface is used for both modem and fax operations. Fax image
coding and decoding must be done in the computer.

Your modem supports Group 3 send and receive facsimile
functions. For normal fax operation, you must connect the modem
to a computer, usually a PC. The computer serves as the
input/output device for the fax function. The RS-232 serial
connection or the ZyXEL serial port interface connects you modem
to the computer. Your modem uses the same interface for both data
and fax applications. In fax operations, the modem performs
protocol handshaking and image data transfer. The computer
handles image data creation, capturing, conversion, compression,
decompression, retrieval, and storage.

Fax Operation 53

ITU-T T.30 Fax Protocol

The U-336R/RE takes full control of the ITU-T T.30 fax protocol,
also known as G3 fax handshaking signals and procedures. Your
modem initiates and terminates fax calls, manages communications
sessions, and transports image data relieving the computer fax
software of the T.30 protocol handling.

You modem allows for fax speeds up to 14400 bps when
transmitting to a fax machine which complies with the V.17 fax
standard. Speeds will fall back to 12000, 9600, or 7200 bps if poor
line conditions are encountered. When connecting to a G3 fax
device, your modem allows for fax speeds up to 9600 bps and will
automatically fall back to 7200, 4800, and 2400 bps if the line
quality is poor.

Fax Command sets

Your modem supports four command sets for fax operation:

• Class 1 command set.

• TIA PN-2388 Class 2 command set.

• TIA 592 Class 2.0 command set.

• ZyXEL Extended Fax AT command set.

Defining the Fax Command Sets

The EIA Class 1 and Class 2 fax commands are a set of AT fax
commands defined by EIA/TIA (Telecommunications Industry
Association) for controlling fax/modems from a computer through
the serial RS-232 interface. All fax/modems and fax software
supporting this standard will be compatible with each other.

54 Fax Operation

Class 1 commands control on-line modem negotiation while Class 2
commands allow the modem to do many negotiations
simultaneously. The Class 1 protocol uses the modem to transmit
fax data only. The complete organizational overhead for this
protocol is handled by the connected computer. The Class 1
command set is also called the TIA-578 standard.

Several revisions of the class 2 standard exist. Implementations
conforming to different revisions may not work together. A
formally approved version is the Class 2.0 command set, also called
the TIA-592 standard.

Class 1 Command Set

Command Value Description

+FCLASS=n Service class selection.

n=0 Set to Data mode.
n=1 Set to Class 1 mode.
n=2 Set to Class 2 mode.
n=2.0 Set to Class 2.0 mode.
n=6 Set to ZFAX mode.
n=8 Set to Voice mode.

OONOTE: IF S57.4=0 (DEFAULT), THE RESPONSE TO THE +FCLASS=? COMMAND WILL

NOT REPORT CLASS 1 CAPABILITY. THIS IS DUE TO THE FACT THAT SOME FAX
SOFTWARE PACKAGES MAY GET CONFUSED BY THIS RESPONSE.

Command Value Description

+FTS=n 0-255 Stop transmission and pause, in 10 ms

Fax Operation 55

Command Value Description

units.
+FRS=n 0-255 Wait for silence, in 10 ms units.
+FTM=<MOD> Transmit data with <MOD> carrier.
+FRM=<MOD> Receive data with <MOD> carrier.
+FTH=<MOD> Transmit HDLC data with <MOD>

carrier.
+FRH=<MOD> Receive HDLC data with <MOD>

carrier.

The <MOD> parameter for the preceding commands take the
following values:

Value Modulation Speed Requirements

3 V.21 ch. 2 300 Required for FTH & FRH.

+FTH and +FRH support value 3 (V.21 ch. 2 / 300 bps) only.

24 V.27ter 2400 Required for FTM & FRM.
48 V.27ter 4800 Required for FTM & FRM.
72 V.29 7200 Required for FTM & FRM.
73 V.17 7200 Required for FTM & FRM.
74 V.17 w/st 7200 Required for FTM & FRM.
96 V.29 9600 Required for FTM & FRM.
97 V.17 9600 Required for FTM & FRM.
98 V.17 w/st 9600 Required for FTM & FRM.
121 V.17 12000 Required for FTM & FRM.
122 V.17 w/st 12000 Required for FTM & FRM.
145 V.17 14400 Required for FTM & FRM.
146 V.17 w/st 14400 Required for FTM & FRM.

* w/st means with V.17 short training

Class 2 Command Set

The following Class 2 commands are supported and implemented
per TIA PN2388 (8/20/90).

56 Fax Operation

Command Syntax Description

+<command>=<value> Execute a command or set a parameter.
+<command>=? Read permissible settings.
+<command>? Read current setting.

Supported Commands (per TIA PN2388 8/20/90)

Command Value Description

+FAA=n Auto-answer mode parameter:

n=0 Answer as set by +FCLASS.
n=1 DCE answers and auto-determines

type.

+FBADLIN=

<value>

0-255 Bad line threshold (number of

consecutive bad lines for a bad page
parameter):
Determine if Copy Quality OK on the
T.30 flow chart . <value>=0 to 255; a
value of 0 implies that error checking
is disabled.

+FBOR=n Phase C data bit order:

n=0 Select direct bit order.
n=1 Select reversed bit order in receiving

mode for phase C data.

+FBUF? Buffer size; read only parameter:

Allow DTE to determine the
characteristics of the DCE’s buffer
size.

+FCIG="string" Local fax station ID string, for polling

Rx.

+FCLASS=n Service class selection: Refer to

+FCLASS Class 1 command in

previous section.
+FCON DCE responds fax connection .
+FCQ=n Copy quality check capability

Fax Operation 57

Command Value Description

parameter.

n=0 No copy quality check capability.
n=1 Only check 1D phase C data.
n=2 Check both 1D and 2D phase C data.

+FCR=n "Capability to receive" parameter

n=0 DCE will not receive message data or

poll a remote device.

n=1 DCE receives message data or polls a

remote device.
+FDCC=vr,br,wd

,ln,df,ec,bf,st

vr=0 Vertical resolution: Normal; 98 lpi.
vr=1 Vertical resolution: Fine; 196 lpi.
br=0 Bit rate: 2400 bit/s; V.27ter.
br=1 Bit rate: 4800 bit/s; V.27ter.
br=2 Bit rate: 7200 bit/s; V.29 or V.17.
br=3 Bit rate: 9600 bit/s; V.29 or V.17.
br=4 Bit rate: 12000 bit/s; V.17.
br=5 Bit rate: 14400 bit/s; V.17.
wd=0 Page width: 1728 pixels in 215mm.
wd=1 Page width: 2048 pixels in 255mm.

DCE capabilities parameters.

58 Fax Operation

wd=2 Page width: 2432 pixels in 303mm.
ln=0 Page length: A4; 297mm.
ln=1 Page length: B4; 364mm.
ln=2 Page length: unlimited length.
df=0 Data compression format: 1-D;

modified Huffman.

df=1 Data compression format: 2-D;

modified Read.

ec=0 Error correction disabled.
ec=1 Enable error correction mode.

Command Value Description

bf=0 Disable binary file transfer.
st=0 Minimum scan time/line: 0 ms.
st=1 Minimum scan time/line: 5 ms.
st=2 Minimum scan time/line:10 ms

(normal);

5 ms (fine).

st=3 Minimum scan time/line:10 ms.
st=4 Minimum scan time/line:20 ms

(normal); 10ms (fine).

st=5 Minimum scan time/line:20 ms.
st=6 Minimum scan time/line:40 ms

(normal); 20ms (fine).

st=7 Minimum scan time/line:40 ms.

+FDCS=vr,br,wd,

ln,df,ec,bf,st
+FDIS=vr,br,wd,l
n,df,ec,bf,st

+FDR Receive phase C data command;

+FDT=df,vr,wd,

ln

+FET=n End of page or document command:

n=0 More pages; same document.
n=1 End of document; another document

n=2 No more pages or documents.
n=4 Procedure interrupt; another page

n=5 Procedure interrupt; end of document,

n=6 Procedure interrupt; end of document.

Current session parameter; refer to

+FDCC command.

Current session negotiation parameter;

refer to +FDCC command.

initiates document reception.

Transmit phase C data command:

release the DCE to proceed with

negotiation.

follows.

follows.

another document follows.

Fax Operation 59

Command Value Description

+FK Regular fax abort command.
+FLID="string" Local ID string parameter.
+FLO=n Flow control options:

n=0 No flow control.
n=1 Set XON/XOFF software flow

control.

n=2 Set CTS/RTS hardware flow control.

+FLPL=n Document for polling command:

n=0 The DTE has no document available

for polling.

n=1 Indicate a document available for

polling.
+FMDL? Request DCE model.
+FMFR? Request DCE manufacturer .
+FMINSP=n Minimum phase C speed parameter:

n=0 2400 bps.
n=1 4800 bps.
n=2 7200 bps.
n=3 9600 bps.
n=4 12000 bps.
n=5 14400 bps.

+FPHCTO=

<value>

+FPTS=n Page transfer status.

0-255 DTE Phase C response time-out:

Determine how long the DCE will wait

for a command after reaching the end

of data when transmitting in Phase C.

<value>=0 to 255; 100 ms units.

n=1 Received page good.
n=2 Page bad; retrain requested.
n=3 Page good; retrain requested.
n=4 Page bad; procedure interrupt

requested.

60 Fax Operation

Command Value Description

n=5 Page good; procedure interrupt

requested.
+FREL=n Phase C received EOL alignment:

n=0 The EOL patterns are bit aligned as

received.

n=1 The last received bits of EOL patterns

are byte aligned by the DCE, with

necessary zero fill bits inserted. Refer

to TIA PN-2388 for details.
+FREV? Request the DCE revision

identification.
+FSPL=n "Enable polling" command:

n=0 Disable polling.

n=1 Enable polling.
All other +F commands are not supported, but the modem will
respond OK. In many cases this means "don't care." See PN 2388
for command details.

Class 2 Command Responses

Response Value Function and Description

+FCFR Confirmation.
+FCIG:"string

Report remote ID response CIG.
"
+FCON Facsimile connection response.
+FCSI:"string" Report remote ID response CSI.
+FDCS:vr,br,
wd,ln,df,ec,bf,s

Report session parameters response;

refer to +FDCC=.... command.

t
+FDIS:vr,br,w
d,ln,df,ec,bf,st
+FDTC:vr,br,
wd,ln,df,ec,bf,s

Report session negotiation parameters

response; refer to +FDCC=.... command.

Report remote capabilities response;

refer to +FDCC=.... command.

Fax Operation 61

Response Value Function and Description

t
+FET:n Post page message response; refer to the

+FET=n command.
+FHNG:n Call termination status response.

n=00 Normal and proper end of connection.
n=10 Transmit error on phase A hang up code.
n=20 Transmit error on phase B hang up code.
n=40 Transmit error on phase C hang up code.
n=50 Transmit error on phase D hang up code.
n=70 Receive error on phase B hang up code.
n=90 Receive error on phase C hang up code.
n=100 Receive error on phase D hang up code.

+FNSC:"HEX string" Report the non-standard facilities

command frame.
+FNSF:"HEX string" Report the non-standard facilities frame

response.
+FNSS:"HEX string" Report the non-standard setup frame

response.
+FPOLL Remote polling indication.
+FPTS:n Receive page transfer status response;

refer to +FPTS=n command.
+FTSI:"string" Report remote ID response TSI.
+FVOICE Transition to Voice response.

Class 2 Flow Control

Flow control is necessary to match the DTE-DCE data rate to the
line signaling rate while transmitting or receiving Group 3 (T.4)
data. In Class 2 fax mode, both hardware (RTS/CTS) and software
(XON/XOFF) flow control are enabled.

62 Fax Operation

Class 2.0 Command Set

Command Syntax Description

+<command>=<value> Execute a command or set a parameter.
+<command>=? Read permissible settings.
+<command>? Read the current setting.

Supported Commands

Command Value Description

+FAA=n Auto-answer mode parameter:

n=0 DCE answers as set by +FCLASS.
n=1 DCE answers and auto-determines call

type.
+FBO=n Phase C data bit order:

n=0 Select direct bit order.
n=1 Select reversed bit order in receiving

mode for phase C data.
+FBS? Buffer size parameter; read only.
+FCC=vr,br,w

d,ln,df,ec,bf,st

+FCLASS=n Service class selection. Refer to

+FCO DCE response fax connection made.
+FCQ=<rq>,

<tq>

rq=0 DCE Receive Copy Quality Checking

rq=1 DCE Receive Copy Quality Checking

rq=2 DCE Receive Copy Quality Correction

DCE capability parameter. Refer to

+FDCC command in Class 2 for parameter

settings.

+FCLASS Class 1 command in previous

section.

Copy quality check capability parameter

disabled.

enabled.

enabled.

Fax Operation 63

Command Value Description

tq=0 DCE Transmit Copy Quality Checking

disabled.

tq=1 DCE Transmit Copy Quality Checking

enabled.

tq=2 DCE Transmit Copy Quality Correction

enabled.
+FCR=n "Capability to receive" parameter

n=0 DCE will not receive message or poll a

remote device.

n=1 DCE receives message data or polls a

remote device
+FCT=n 0-255 DTE phase C time-out parameter. n=0-

255, 1s units.
+FDR Receive phase C data command initiates

document reception
+FDT Transmit phase C data command:

releases the DCE to proceed with

negotiation
+FEA=n Phase C received EOL alignment

parameter

n=0 Determine that T.4 EOL patterns are bit

aligned (as received).

n=1 Determine that the last received bits of

T.4 EOL patterns are byte aligned by the

DCE, with necessary zero fill bits

inserted.
+FIE=n Procedure interrupt parameter

n=0 Procedure interrupt requests from the

remote station are ignored, and not

reported to the DTE.

n=1 Procedure interrupt requests from the

remote station are accepted, negotiated

64 Fax Operation

Command Value Description

and reported using the +FVO response.
+FIP Initialize facsimile parameters to factory

default.
+FIS=vr,br,wd

,ln,df,ec,bf,st

+FKS Session termination command.
+FLI="string" Local ID string parameter.
+FLO=n Flow control options:

n=0 No flow control.
n=1 Set XON/XOFF software flow control.
n=2 Set CTS/RTS hardware flow control.

+FLP=n Document for polling command:

n=0 The DTE has no document for polling.
n=1 Indicated document available for polling.

+FMI? Request DCE manufacturer

+FMM? Request DCE model identification.
+FMR? Request DCE revision identification.
+FMS=n Minimum phase C speed parameter. refer

+FNR=rpr,

tpr,idr,nsr

rpr=0 Receiver parameters are not reported.

rpr=1 Receiver parameters are reported. +FIS:

tpr=0 Transmitter Parameters are not reported.

Current session parameter. refer to

+FDCC Class 2 command in previous

section parameter settings.

identification.

to +FMINSP Class 2 command in

previos section for parameter settings.

Negotiation message reporting control

parameters:

+FIS: and +FTC: response reports are

suppressed.

and +FTC: response reports are

generated.

+FCS: response reports are suppressed.

Fax Operation 65

Command Value Description

(+FCS parameter is still loaded)

tpr=1 Transmitter Parameters are reported.

+FCS: response reports are generated.

idr=0 ID Strings are not reported. +FTI: +FCI:

and +FPI: response reports are

suppressed.

idr=1 ID Strings are reported. +FNF:, +FNS:

and +FNC: response reports are

generated.

nsr=0 Non-standard frames are not reported.

+FTI: +FCI: and +FPI: response reports

are suppressed.

nsr=1 Non-standard frames are reported. +FTI:,

+FCI: and +FPI: response reports are

generated.
+FNS="string

"

+FPI="string" Local fax station ID string, for polling

+FPR=n Serial port rate control parameter:

n=0 Automatic DTE rate detection by the

n>0 Serial rate is fixed at the value multiplied

+FPS=n Page transfer status: refer to the +FPTS

+FRQ=pgl,cbl Receiving quality threshold parameters:

pgl= Specify the percentage of good lines (e.g.

Non-standard byte string parameter.

"string": string of hexadecimal coded

octets.

Rx.

DCE.

by 2400 bps. For example, when n=8, the

DTE rate is equal to 19200 bps

(8x2400).

Class 2 command in previous sections for

settings.

66 Fax Operation

Command Value Description

0-64
(HEX
value)

with negotiated number of pixels)

required for a page considered

acceptable. The percentage of good lines

would be computed by the equation:

100 x (<lc> - <bl>) / <lc>

lc: total line count as reported in the

+FPS: response.

bl: bad line count as reported in the

+FPS: response.

If the resulting value is less than the value

in <pgl>, the page is unacceptable.

cbl=
0-FF
(HEX
value)

Specify the maximum tolerable number of

consecutive bad lines. If this value is

exceeded for a given page, the DCE shall

consider the page unacceptable.
+FSP=n Enable polling command:

n=0 Disable polling.
n=1 Enable polling.

Class 2.0 Command Responses

Response Value Function and Description

+FCI:"CSI ID
string"

Report remote ID response, Called Station

ID.
+FCO Fax connection established response.
+FCS:vr,br,w
d,
ln,df,ec,bf,st

negotiated session parameters (DCS

frame information) response. Refer to

+FIS= comnd.
+FET:<ppm> Post page message response:

ppm=0 Another page next, same document.
ppm=1 Another document next.
ppm=2 No more pages of documents.
ppm=3 Another page next, same document,

Fax Operation 67

Response Value Function and Description

procedure interrupt requested.

ppm=4 Another document next, procedure

interrupt requested.

ppm=5 No more documents or pages, procedure

interrupt requested.
+FHS:<hsc> Call termination status:

hsc=
0-0F
hsc=
10-1F
hsc=
20-3F
hsc=
40-4F
hsc=
50-6F
hsc=
70-8F
hsc=
90-9F
hsc=

A0-BF
+FIS:vr,br,wd
,ln,df,ec,bf,st

+FNC:
"NSC FIF
string"
+FNF:
"NSF FIF
string"

Call placement and termination. Refer to
TIA-592 for details.
Transmit phase A and miscellaneous
errors. Refer to TIA-592 for details.
Transmit phase B hang up codes. Refer
to TIA-592 for details.
Transmit phase C hang up codes. Refer
to TIA-592 for details.
Transmit phase D hang up codes. Refer
to TIA-592 for details.
Receive phase B hang up codes. Refer to
TIA-592 for details.
Receive phase C hang up codes. Refer to
TIA-592 for details.
Receive phase D hang up codes. Refer to
TIA-592 for details.
Remote fax station capabilities (DIS
frame information) response refer to
+FIS=... command for a description of
sub-parameters.
Report NSC (non-standard Commands)
frame

Report NSF (non-standard Facilities)
frame.

68 Fax Operation

Response Value Function and Description

+FNS:
"NSS FIF
string"
+FPI:
"CIG ID
string"
+FPO Remote polling indication.
+FPS:ppr,lc,b
lc,cblc,lbc

ppr=1 Received page good.

ppr=2 Page bad; retrain requested.

ppr=3 Page good; retrain requested.

ppr=4 Page good; remote request for procedure

ppr=5 Page bad; retrain requested; remote

+FTC:vr,br,w
d,ln,df,ec,bf,
st

+FTI:
"TSI ID
string"
+FVO Report transition to voice.

Report NSS (non-standard Setup) frame.

Report remote ID response-Polling
Station ID (CIG).

.30 phase C page reception response:

interrupt accepted.

request for procedure interrupt accepted.
The receiving DCE may count <lc>,
<blc>, <cblc> and <lbc> due to DCE
buffer overflow and report them:
lc: line count.
blc: bad line count
cblc: maximum consecutive bad line
count.
lbc: lost byte count.
Remote fax station capabilities (DCT
frame information) response refer to
+FIS=... command for the description of
sub-parameters.
Remote ID response-Transmit Station ID
(TSI).

Fax Operation 69

Extended Fax AT Command Set

Extended Fax AT Commands are unique to ZyXEL modems. The
computer controls the modem through a set of extended fax AT
commands and the modem responds with a set of status report
result codes. During data state, compressed fax image data is
flowing between the modem and computer. The default serial
connection speed is 38400 bps, and it is higher than the fax link
rate. CTS/RTS hardware flow control is used to regulate the data
flow.

Your modem accepts the extended fax AT commands to set the
modem mode and fax parameters. Besides the extended fax AT
commands, the modem accepts all the other AT commands
described in this chapter. For instance, you can use ATD to make a
fax call, or ATA to answer an incoming fax call. When using the
extended Fax AT commands, you need to send the command
AT+FCLASS=6 first. Following are the fax related AT commands:

Mode Settings

Command Function

#F Set the modem into V.17G3 FAX mode. Same

function as the extended AT command AT&N32.

#B0 Set fax receiving mode. The connection parameters

and received fax data are sent to the DTE
continuously following the connect message.
(Default)

#B1 Set fax receiving mode. The messages are separated

from the received fax data. The modem sends
CONNECT FAX and ZyXEL first, then it waits for
the DC2 character (hex18) to send the fax data.
When the modem receives a DC2 from the DTE, it
starts to send the fax connection
parameters/SnnnnVnTnRnLnCnP<string><CR><LF
> then the received fax data. In this mode, the

70 Fax Operation

Command Function

modem will wait for DC2 at the beginning of every
page. The DTE software should detect the page
separator RTC and then sends the DC2 to receive
the next page of fax data. This mode is used with a
BBS receiving faxes.

#B2 This mode is for the polling feature of the modem.

In this mode, the modem will send a polling signal
to the remote fax device to ask to receive a fax from
the remote fax device. The received fax data will be
sent to the DTE continuously following the
connection message.

#B3 Displays the ring cadence.

Parameter Setting

Command Function

#V0 Set to normal vertical resolution.
#V1 Set to high vertical resolution.
#T0 Set to one dimensional coding scheme.
#T1 Set to two dimensional coding scheme.
#R0 Set recording width: 1728 picture elements along a

scan line length of 215 mm.

#R1 Set recording width: 2048 picture elements along a

scan line length of 255 mm.

#R2 Set recording width: 2432 picture elements along a

scan line length of 303 mm.
#L0 Set maximum recording length: A4 (297 mm ).
#L1 Set maximum recording length: B4 ( 364 mm ).
#L2 Set maximum recording length: unlimited.
#C0 Set minimum scan line time capability of the

receiver: 20 ms at 3.85 line/mm, T(7.7)=T(3.85).
#C1 Set minimum scan line time capability of the

receiver: 5 ms at 3.85 line/mm, T(7.7)=T(3.85).

Fax Operation 71

Command Function

#C2 Set minimum scan line time capability of the

receiver: 10 ms at 3.85 line/mm, T(7.7)=T(3.85).
#C3 Set minimum scan line time capability of the

receiver: 20 ms at 3.85 line/mm, T(7.7)=1/2

T(3.85).
#C4 Set minimum scan line time capability of the

receiver: 40 ms at 3.85 line/mm, T(7.7)=T(3.85).
#C5 Set minimum scan line time capability of the

receiver: 40 ms at 3.85 line/mm, T(7.7)=1/2

T(3.85).
#C6 Set minimum scan line time capability of the

receiver: 10 ms at 3.85 line/mm, T(7.7)=1/2

T(3.85).
#C7 Set minimum scan line time capability of the

receiver: 0 ms at 3.85 line/mm, T(7.7)=T(3.85).
#P<string> Set local phone number to the phone number

following the character 'P' can store up to 25

characters. The modem will exchange this phone

number with the remote fax machine during initial

handshaking.

Status Report Result Codes

When your modem is in fax mode, each ATD or ATA command
will try to establish a fax connection. Your modem will send a
status report result code back to the DTE (computer).

NO DIAL
TONE
NO CARRIER Handshake fails or no carrier is detected or

BUSY Other party's phone line is busy.
NO ANSWER Quiet answer is not detected before time-out.

72 Fax Operation

Tried to dial but no dial tone is detected.

time-out.

CONNECT FAX See below.

When a fax connection is successfully established, the modem
returns this message:

CONNECT FAX/SnnnnVnTnRnLnCnP<string>

This message includes the connection speed and the fax parameters
explained in the table below:

Field Description

Snnnn Fax connection speed; nnnn is a 4-digit number

representing the connection speed. nnnn =1440,
1200, 9600, 7200, etc., 1440 and 1200 stand for

14400 and 12000.
Vn Vertical resolution; n = 0 or 1.
Tn Coding scheme; n = 0 or 1.
Rn Recording width; n = 0, 1, or 2.
Ln Recording length; n = 0, 1, or 2.
Cn Scan line time; n = 0 to 7.
P<string> Remote fax number.

After each fax disconnection, the following result code is sent back
to the DTE:

DISCONNECTnP<string>

This result code informs DTE of the disconnecting status.

Field Description

DISCONNECT0 Disconnect with remote confirmation.
DISCONNECT1 Disconnect without remote confirmation.
P<string> Remote fax number.

Fax Operation 73

The basic AT commands ATV0 and ATQ1 do not affect the above
CONNECT and DISCONNECT status report result codes. The
modem will always return the same status format as above.

Flow Control

In extended fax AT command mode, your modem always uses
hardware (CTS/RTS) flow control. The flow control signaling used
sending a fax is:

• CTS is used by your modem for DTE flow control. When the

modem turns CTS off, the buffer inside the modem is full and
cannot accept any more data. The computer should send data
only when CTS is ON.

• RTS is used by the computer to signal your modem that the fax

message is finished. As soon as RTS off is detected, the modem
starts the post message handshaking to make sure that the
remote facsimile has received the fax message successfully.
Then it hangs up the phone and sends a status report to the
DTE.

If you want to send a multi-page fax, just add the RTC signal
between the fax message of each page. The modem detects the
RTC signal automatically, handshakes the multi-page procedure
with the remote facsimile and sends the next page.

The following flow control signaling is used while receiving a fax:

• CTS is not used when receiving fax.

• RTS is used to inform your modem that the computer cannot

When finished receiving the fax message, your modem will turn off
CD then send a status report result code to the DTE.

74 Fax Operation

accept data at this moment. The modem will not pass received
data to the DTE if RTS is turned off.

Fax Reception from a BBS

Your modem can automatically detect data and fax calls and allow
BBS software to receive faxes on the same phone line. To allow
your BBS to receive incoming faxes, make the following set-up
changes in your BBS:

1. Add the string #B1+FCLASS=6 to the init string. Be sure the

+FCLASS=6 command is the last command.

2. Change one of the messages in the list to CONNECT FAX.

3. Set the external mail string to ZyXEL and give it an error level.

4. In your BBS batch file, if the error level matches the external

mail, execute

rcvfax 2 /p:comport [/w:workpath]

This setting will enable the BBS to receive a fax and store it

automatically.
The following is a sample setting for the Front Door system.

• Add these commands to the init string:
X7#B1+FCLASS=6

• Change the connection message to:

300 CONNECT 4800 CONNECT 4800
1200 CONNECT 1200 9600 CONNECT 7200
1275 CONNECT FAX 19200 CONNECT 9600
2400 CONNECT 2400 38400 CONNECT

14400

• Set external mail as:

String Error Level

Fax Operation 75

String Error Level

1 ZyXEL 100
2
3

The following is a sample setting in the BINKLEY.CFG file for a
Binkley system.

Init AT&FX7S0=1#B1+FCLASS=6
ExtrnMail ZyXEL errorlevel

76 Fax Operation

8 AT Command Set Summaries

Basic AT Command Set

Command Options Function & Description Ref.

A/ Re-execute the last command once.
A> Re-execute the last command once or

repeat the last call up to 9 times. (See
also S8)

<any key> Terminate current connection attempt

when enter in handshaking state.

+++ Escape sequence code, entered in data

state, wait for modem to return to
command state.

Command Options Function & Description Ref.

A Go on-line in answer mode. (See

also S39.2, S43.6)

Bn Handshake option. S28.7

B0 * Select CCITT V.22 for 1200 bps.
B1 Select Bell 212A for 1200 bps

communication.

Ds Dial s (numbers and options) that

follow (see also S38.0, S35.4). The

options of s are listed as follows:
0-9, #, * Digits for dialing.
P Pulse dialing. S23.1
T Ton dialing. S23.1

AT Command Set Summaries 77

Command Options Function & Description Ref.

, Pause for a time specified in S8.

Remaining digits will be dialed as in-

band DTMF.
; Return to command state after

dialing.
! Hook flash.
@ Wait for a 5 second silence before

proceeding.
R Reverse handshake (go on-line in

Answer mode).
W Wait for second dial tone.

Remaining digits will be dialed as in-

band DTMF.

DL Repeat last ATD command.
DSn n=0-49 Dial number stored in non-volatile

RAM at location 'n'; use “+” to dial

two consecutive numbers for

bundling or MPPP calls.

En Command mode local echo of

keyboard commands.
E0 Echo off.
E1 * Echo on.

Hn On/off hook control

H0 * Hang up (on-hook) the modem or

ISDN, same as 'ATH'.
H1 Off hook the modem.

In Display inquired information.

I0 Display numerical product code,

same as 'ATI'.
I1 Display product information and

ROM checksum.
I2 Display modem link status report.

S17.5

S44.3

S23.0

78 AT Command Set Summaries

Command Options Function & Description Ref.

I12 Display physical layer status.

Ln n=0-7

4 *

Mn Speaker control. S21.1-2

M0 Speaker always OFF.
M1 * Speaker ON until call is answered.
M2 Speaker always ON.
M3 Speaker ON after the last digit is

Nn n=0-7

5 *

O Return to on-line state.
O1 Force modem to request a retrain.
Qn Result code displayed. S23.7

Q0 * Modem returns result code.
Q1 Modem does not return result code.
Q2 Modem returns result code but quiet

Sr.b=n Set bit 'b' of S-register 'r' to value 'n'.

Sr.b? Display value of bit 'b' of S-register

Sr=n Set S-register 'r' to value 'n'. 'n' must

Sr? Display value stored in S-register 'r'.
T Ton dial. S23.1
UPX Download firmware to the Flash

Speaker volume control. The higher

the value, the higher the volume.

dialed out and OFF when carrier is

detected.

Ring volume control.'N0' will

disable the audio ring function.

after answering on a RING (see also

S42.2).

'n' is a binary digit '0' or '1'.

'r'.

be a decimal number between 0 and

255.

EPROM by using Xmodem

protocol.

S24.4-6

S24.0-2

S40.1

AT Command Set Summaries 79

Command Options Function & Description Ref.

Vn Sets display type for Result Codes. S23.6

V0 Display result code in numeric form.

(See also S35.7 and the result code

table of 'ATXn')
V1 * Display result code in verbose form.

Xn n=0-7

5 *

Zn n=0-4 Reset modem and set power-on

Zn Reset modem and load user profile n

Z4 Reset modem and load factory

$ Basic command summary help.
&$ Extended 'AT&' command summary

*$ Extended 'AT*' command summary

Result code options, see the Options

Table.

profile.

(0-3).

settings.

help.

help.

S23.3-5

S15.5-7

Description of ATI2 Output:

The Link Status Report output appears as follows:

ZyXEL U-MODEM LINK STATUS REPORT
Chars Sent 2420
Chars Received 2420
Octets Sent 950
Octets Received 950
Blocks Sent 13
Blocks Received 13
Blocks Resent 0

80 AT Command Set Summaries

Max Outstanding 8
Max Block Size 256
Retrain Requested 0
Link Duration 1
Retrain Granted 0
T401 Timeouts 0
T402 Timeouts 0
FCS Errors 0
Round Trip Delay 10
Xmitter Underrun 0
Receiver Overrun 0
Last Speed/Protocol Connect

14400/ARQ/V42b
Disconnect Reason Local Hangup

Data Type Description

Chars Data received from or sent to DTE (PC).

(Formatted as 7,E,1 or 7,O,1 or 8,N,1 etc.)

Octets Data received from or sent to remote modem in

error control mode. (Compressed if data
compression was enabled.)

Block Framed Octets. (Delimited by the unique bit

pattern "01111110" known as a flag.)

Output Parameter Output Value Description

Chars Sent Number of characters DTE has sent to

modem.

AT Command Set Summaries 81

Output Parameter Output Value Description

Chars Received Number of characters modem has sent to

DTE.
Octets Sent Number of data bytes sent to remote modem
Octets Received Number of data bytes received from remote

modem.
Blocks Sent Number of data blocks sent to remote

modem.
Blocks Received Number of data blocks received from remote

modem.
Blocks Resent Number of blocks resent due to remote

modem request. (If there were many blocks

resent, you may have experienced line

trouble or protocol incompatibility.)
Max Outstanding Maximum blocks received without

acknowledgment by remote modem.
Max Block Size Maximum octets contain in a block.
Retrains Requested The number of times local modem requested

retrain.
Link Duration Total link duration time (in minutes).
Retrains Granted The number of times remote modem

requested retrain.
T401 Time-outs For protocol maintenance, modem probably

recovered.
T402 Time-outs For protocol maintenance, modem probably

recovered.
FCS Errors Errors in frame (block) checksum. (If there

were many FCS Errors, you may have

experienced problems on the line.)
Round Trip Delay Time (Units 1/2400 sec.)
Xmitter Underrun For modem's processor power measurement.
Receiver Overrun For modem's processor power measurement.
Disconnect Reason Local Hang-up Remote Hang-up

82 AT Command Set Summaries

Output Parameter Output Value Description

Carrier Lost On-Line (Not

Resent Expiration Protocol Error

Break Time-out DTR Dropped

Carrier Lost 1

(No handshaking

response)

Security check

ATH command

D/V hang up.

Extended AT& Command Set

Command Options Function & Description Ref.

&Bn Data rate, terminal-to-modem.

(DTE/DCE)

&B0 DTE rate follows connection rate.

(See also S44.6)

&B1 * DTE/DCE rate fixed at DTE setting

(See also S18, S20, and S44.6)

&Cn Carrier Detect (CD) options. S21.4

&C0 CD always ON (See also S42.7).
&C1 * CD tracks presence of carrier (See

also S38.3, S42.7).

&Dn Data Terminal Ready (DTR) options.

(See also S25)

&D0 Ignore DTR signal, assume DTR is

always ON.

&D1 108.1, DTR OFF-ON transition

causes dial of the default number.
(See also 'AT*Dn' and S48.4)

&D2 * 108.2, Data Terminal Ready, DTR

OFF causes the modem to hang up.

disconnected)

Carrier Lost 2 (Remote
hang-up, busy tone)
Keyboard Abort
Inactivity.

S28.6

S21.6-7

AT Command Set Summaries 83

Command Options Function & Description Ref.

&D3 Same as &D2 but DTR OFF causes

the modem to hang up and reset from
profile 0.

&F Load factory settings to RAM as

active configuration.

&Gn Guard tone options. S28.4-5

&G0 * No guard tone (within USA,

Canada).

&G2 1800 Hz guard tone.

&Hn Data flow control, DTE/DCE. S27.3-5

&H0 Flow control disabled.
&H3 * Hardware (CTS/RTS) flow control.
&H4 Software (XON/XOFF) flow control.

&Jn Type of Phone line. S28.0

&J0 Single phone line, RJ11.
&J1 Multiple phone/modem line,

RJ12/RJ13.

&Kn Modem error control and data

compression.
&K0 No error control.(Same as AT&K)
&K1 MNP4 (See also S41.0).
&K2 MNP4+MNP5 (See also S38.5,

S41.0).
&K3 V.42+MNP4.
&K4 * V.42+V.42bis, compatible with &K2

(See also S38.5).

&Ln &L0 * Dial-up line. S14.2-3

&L1 2W leased line.
&L2 4W leased line.

&Mn Synchronous/asynchronous mode

selection.
&M0 * Asynchronous mode with data

S27.0-2

S14.6-7

84 AT Command Set Summaries

Command Options Function & Description Ref.

buffering.
&M1 Asynchronous command,

synchronous data.
&M2 Direct asynchronous mode, no data

buffering.
&M3 Synchronous mode.

&Nn Modem link mode options

(DCE/DCE). (See also S43.7, S48.1)
&N0 * Multi-Auto, auto negotiate highest

possible link rate: V.34, ZyX 19200,

ZyX16800, V.32bis, V.32, V.22bis,

V.22 and Bell 212A, G3 Fax

V.17/V.29/V.27ter and cellular

modes. (See also S38.4, S43.0,

S43.1, S43.3 and S48.5)
&N1 V.33 14400/12000 (models with 4-

wire leased line only)
&N2 V.33 12000 (models with 4-wire

leased line only)
&N3 V.32 9600T/9600/7200T/4800
&N4 V.32 9600/7200/4800
&N5 V.32 4800
&N6 V.29 9600 (models with 4-wire

leased lines only)
&N7 V.29 7200 (models with 4-wire

leased lines only)
&N8 V.29 4800 (models with 4-wire

leased lines only)
&N9 V.27bis 4800 (models with 4-wire

leased lines only)
&N10 V.27bis 2400 (models with 4-wire

leased lines only)

S19

AT Command Set Summaries 85

Command Options Function & Description Ref.

&N11 V.26bis 2400 (models with 4-wire

leased lines only)
&N12 V.23 1200/75 (See also S48b3,

S52b7)
&N13 V.23 600/75 (See also S52b7)
&N14 V.22bis 2400/1200
&N15 V.22 1200
&N16 V.21 300
&N17 V.32bis

14400/12000/9600/7200/4800
&N18 V.32bis 12000/9600/7200/4800
&N19 V.32bis 7200/4800
&N24 BELL 212A 1200
&N25 BELL 103 300
&N32 G3 Fax V.17/V.29/V.27ter

14400/12000/9600/7200/4800/2400

(See also S42.4).
&N34 ZyXEL 19200
&N35 ZyXEL 16800
&N36 ZyXEL 14400
&N37 ZyXEL 12000
&N38 ZyXEL 9600
&N39 ZyXEL 7200
&N42 CELL 14400
&N43 CELL 12000
&N44 CELL 9600
&N45 CELL 7200
&N46 CELL 4800T
&N62 V.34 28800
&N63 V.34 26400
&N64 V.34 24000
&N65 V.34 21600

86 AT Command Set Summaries

Command Options Function & Description Ref.

&N66 V.34 19200
&N67 V.34 16800
&N68 V.34 14400
&N69 V.34 12000
&N70 V.34 9600
&N71 V.34 7200
&N72 V.34 4800
&N73 V.34 2400

&Pn Pulse dial make/break ratio. S23.2

&P0 * make / break, 39% / 61%
&P1 make / break, 33% / 67%

&Rn RTS (Request To Send) function

selection
&R0 CTS tracks RTS, response delay is

set in S26.
&R1 * Ignore RTS, assumes RTS always

ON.

&Sn Data Set Ready (DSR) function

selection.
&S0 * DSR overridden, DSR always ON.
&S1 DSR according to CCITT (ITU-

TSS). (See also S41.5, S44.4)

&Tn Modem testing. S16

&T0 Terminate test in progress.
&T1 Initiate Analog Loop-back (ALB)

test.
&T3 Initiate Local Digital Loop-back

(LDL) test.
&T4 Grant Remote Digital Loop-back

request from remote modem.
&T5 Deny Remote Digital Loop-back

request from remote modem.

S21.5

S21.3

S14.1

S14.1

AT Command Set Summaries 87

Command Options Function & Description Ref.

&T6 Initiate Remote Digital Loop-back

(RDL) test.
&T7 Initiate Remote Digital Loop-back

with self test (RDL+ST).
&T8 Initiate Analog Loop-back with self

test. (ALB+ST).

&Vn View profile settings.

&V0 View current active settings.
&Vn View the (n-1) user profile settings

(n=1-4).
&V5 View factory default settings.

&Wn n=0-3 Write current settings to user profile

n in non-volatile RAM. (See also

S35.6)

&Xn Synchronous mode timing (clock)

source selection.
&X0 * Modem provides synchronous

transmit clock signal (Internal clock

to pin 15 of EIA-232D).
&X1 Terminal provides synchronous

transmit clock signal (External clock

from pin 24 of EIA-232D).
&X2 Received carrier provides

synchronous transmit clock signal

(Remote or Slave clock to pin 15 of

EIA-232D).

&Yn Break handling. Destructive Break

clears the buffer. Expedited Break is

sent immediately to the remote

system. (For internal modem only.)
&Y0 Destructive, expedited.
&Y1 * Nondestructive, expedited.

S14.4-5

S28.2-3

88 AT Command Set Summaries