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