Multi-Tech Systems MT2834BL User Manual

MT2834BA/MT2834BL Series

Intelligent Data/Fax Modems

User Guide

User Guide

S000300B Revision B

MultiModem

MT2834BA, MT2834BAI, MT2834BL, MT2834BLI

This publication may not be reproduced, in whole or in part, without prior expressed written permission
from Multi-Tech Systems, Inc. All rights reserved.

Copyright 2004©, by Multi-Tech Systems, Inc.

Multi-Tech Systems, Inc. makes no representations or warranties with respect to the contents hereof and
specifically disclaims any implied warranties of merchantability or fitness for any particular purpose.
Furthermore, Multi-Tech Systems, Inc. reserves the right to revise this publication and to make changes
from time to time in the content hereof without obligation of Multi-Tech Systems, Inc. to notify any person
or organization of such revisions or changes.

Record of Revisions
Rev. Date Description
A 04/23/03 Initial release of this combination.

Replaces MT2834BA/MT2834BAI User Guide 88312001 Rev. B and
MT2834BL/MT2834BLI User Guide 88312100 Rev. A.
Included Product Update 82076600 (MT2834BL AT commands $LL).

B 01/20/04 Corrected 4-wire Leased Line diagrams in Appendix E.

II

Models:

Patents

This device is covered by one or more of the following patents: 6,031,867; 6,012,113; 6,009,082;
5,905,794; 5,864,560; 5,815,567; 5,815,503; 5,812,534; 5,809,068; 5,790,532; 5,764,628; 5,764,627;
5,754,589; 5,724,356; 5,673,268; 5,673,257; 5,644,594; 5,628,030; 5,619,508; 5,617,423; 5,600,649;
5,592,586; 5,577,041; 5,574,725; 5,559,793; 5,546,448; 5,546,395; 5,535,204; 5,500,859; 5,471,470;
5,463,616; 5,453,986; 5,452,289; 5,450,425; D353,598; 5,355,365; 5,309,562; 5,301,274. Other
patents pending.

Trademarks

Trademarks of Multi-Tech Systems, Inc. are as follows: MultiModemII, Multi-Tech and the Multi-Tech logo.
All other brands and product names mentioned in this publication are trademarks or registered

trademarks of their respective companies.

Technical Support
Country By Email By Phone

France: [e-mail] +(33) 1-64 61 09 81
India: [e-mail] [phone]
U.K.: [e-mail] +(44) 118 959 7774
U.S and Canada: [e-mail] [phone]
Rest of the World: [e-mail] +[phone]

Multi-Tech Systems, Inc.

2205 Woodale Drive

Mounds View, Minnesota 55112 U.S.A.

[phone] or [phone]

U. S. Fax [phone]

Technical Support [phone]

Internet Address: http://www.multitech.com

Contents

Chapter 1 - Introduction and Description......................................................................... 5

1.1 Introduction...................................................................................................................................... 6

1.2 How To Use This Manual................................................................................................................. 6

1.3 Modem Features ............................................................................................................................. 7

1.3.1 MT2834BA/BL Series Features ...............................................................................................8

1.4 Fax Features ................................................................................................................................... 8

1.5 Technical Specifications .................................................................................................................. 9

1.6 Power .............................................................................................................................................. 10

1.7 Modem LED Indicators.................................................................................................................... 11

1.8 Controls on PC Board ..................................................................................................................... 12

Chapter 2 - Installation and Connection......................................................................... 13

2.1 What Is in Your Modem Package? .................................................................................................. 14

2.2 Installation ....................................................................................................................................... 14

2.2.1 Safety Warnings........................................................................................................................ 14

2.2.2 Installation Procedure ............................................................................................................... 14

2.3 Installing PhoneTools, the Data Communications Software ............................................................ 16

2.4 Is Your Modem Ready for Use? ...................................................................................................... 16

Chapter 3 - Software Configuration and Modem Basics .............................................. 17

3.1 Introduction...................................................................................................................................... 18

3.2 Configuring Y our Software............................................................................................................... 18

3.2.1 ConfiguringSoftware for Your Modem ....................................................................................... 18

3.3 PC Initialization Strings ................................................................................................................... 18

3.3.1 Changing Default Parameters................................................................................................... 19

3.3.2 Other Parameters ..................................................................................................................... 19

3.4 Configuring Software for Your Computer......................................................................................... 19

3.5 Modem Basics................................................................................................................................. 20

3.5.1 Simple Operations .................................................................................................................... 20

3.6 The Answer/Originate - Voice/Data Toggle Switch .......................................................................... 20

Chapter 4 - Manual Dial and Automatic Answer ............................................................ 21

4.1 Introduction...................................................................................................................................... 22

4.2 Dialing/On-Line/Answering .............................................................................................................. 22

4.3 Automatic Leased Line Restoral Operation.....................................................................................23

4.4 Manual Dial Backup Call Termination.............................................................................................. 23

4.5 Dial Backup and Leased Line Restoral ........................................................................................... 23

4.6 Dial-Up Operation............................................................................................................................ 24

4.7 Manual Call Origination ................................................................................................................... 24

4.8 Automatic Answering....................................................................................................................... 25

4.9 Manual Answering ........................................................................................................................... 25

4.10 Handshaking Details ....................................................................................................................... 26

4.1 1 Call T ermination............................................................................................................................... 26

Chapter 5 - Command Mode............................................................................................ 27

5.1 Introduction...................................................................................................................................... 28

5.1.1 A T Command Editing ................................................................................................................ 28

5.1.2 Functional Modes...................................................................................................................... 28

5.2 Summary of AT Commands............................................................................................................ 29

5.3 Result Codes................................................................................................................................... 32

5.4 Dialing Commands .......................................................................................................................... 33

5.4.1 Dialing Action Commands ......................................................................................................... 33

5.4.2 Dial Modifier Commands........................................................................................................... 34

5.4.3 Phone Number Memory Commands......................................................................................... 37

5.4.4 Configuration and Default Storage Commands ........................................................................ 38

5.4.5 Command Response (Result Code) Commands...................................................................... 40

5.4.6 Phone Line Conditioning Commands........................................................................................ 42

5.4.7 RS-232C Interface Control Commands .................................................................................... 44

5.4.8 Error Correction Commands ..................................................................................................... 46

5.4.9 Flow Control Commands .......................................................................................................... 49

5.4.10 Compression, Error Correction, Flow Control, Pass-Through and Pacing Commands ............ 52

5.4.1 1 Speed Conversion Commands .................................................................................................53

5.4.12 Immediate Action Commands ................................................................................................... 55

5.4.13 Line Probe Commands ............................................................................................................. 57

Chapter 6 - S-Registers.................................................................................................... 58

6.1 Introduction...................................................................................................................................... 59

6.2 Reading and Assigning S-Register Values ......................................................................................66

6.2.1 Examples of Assigning Values .................................................................................................. 66

6.2.2 Examples of Reading V alues .................................................................................................... 66

6.3 AT Command and S-Register Summary ......................................................................................... 67

Chapter 7 - Callback Security and Remote Configuration............................................ 68

7.1 Introduction...................................................................................................................................... 69

7.2 Callback Feature Description .......................................................................................................... 69

7.3 Remote Configuration Description................................................................................................... 70

7.3.1 Initial Setup Procedures for Callback and Remote Configuration. ............................................ 70

7.3.2 Remote Configuration Procedures............................................................................................73

7.4 Remote Configuration and Callback Security AT Commands ......................................................... 74

7.5 Remote Configuration/Callback Security S-Registers..................................................................... 75

Chapter 8 - DIP-Switch Settings...................................................................................... 76

8.1 Introduction...................................................................................................................................... 77

8.2 DIP-Switch Option Settings ............................................................................................................. 78

8.3 Speaker Volume Control ................................................................................................................. 83

8.4 Recording Option Configurations .................................................................................................... 84

Chapter 9 - Warranty, Service and Tech Support .......................................................... 86

9.1 Introduction...................................................................................................................................... 87

9.2 Multi-Tech Systems, Inc. Warranty & Repairs Policies.................................................................... 87

8.3 Online Warranty Registration .......................................................................................................... 88

9.4 Replacement Parts.......................................................................................................................... 89

9.5 Technical Support............................................................................................................................ 89

9.6 Internet Sites ................................................................................................................................... 89

Appendixes....................................................................................................................... 90

Appendix A - Upgrading Your Modem’s Firmware ........................................................................................ 91

Appendix B - Troubleshooting ...................................................................................................................... 94

Appendix C - AT Command Summary ......................................................................................................... 99

Appendix D - V.25bis Operation ................................................................................................................... 107

Appendix E - MultiModemBA Cables............................................................................................................ 113

Appendix F - Regulatory Information............................................................................................................. 114

Index................................................................................................................................ 117

Chapter 1 - Introduction and Description

1.1 Introduction

Welcome to the world of data communications. You have acquired one of the finest intelligent
desktop data/fax modems available today, the MultiModemII BA/BL series modem, from Multi­Tech Systems.

Your MultiModem provides data communication at the following rates:
33,600 - 14,400 bps (Enhanced V.34 / V.32bis)

Chapter 1 - Introduction and Description

The MultiModem also includes dial backup with automatic lease line restoration, adaptive
protocol enhancing used in typical Unix® batch file transfers and support for IBM's AS/400
WindowsTM environments.

1.2 How To Use This Manual

A summary of the information contained in each chapter and appendix follows:

Chapter 1 - Introduction and Description

This chapter begins with a short introduction, followed by a guide (which you are now reading) to
the use of this manual. There is a discussion about what components you can expect in your
modem package. We then provide a more detailed description of the modem, including the
modem’s technical specifications. Chapter 1 includes sections covering power, LED indicators
and a brief summary of PC board controls. (Chapter 8 covers switch settings more thoroughly.)

Chapter 2 - Installation and Connection

Chapter 2 covers the procedure for connecting the modem to your computer and to the phone
line. Details are given, supported by illustrations on the modem's back panel connections as a
guide to install your modem to the point of operation. In addition, this chapter describes the
installation of PhoneTools, the communications software included with your modem.

Chapter 3 - Software Configuration and Modem Basics

TM

and

Chapter 3 documents communication software configuration recommended specifically for the
MultiModem. Other issues covered include setting up initialization strings, changing default
parameters, configuring software for the remote system and file transfer protocols.

Chapter 4 - Manual Dial and Automatic Answer

Chapter 4 covers some modem operations, but delays discussion on Command Mode operation
until Chapter 5. Automatic Leased Line Restoration, Dial backup, Manual Dial Mode, and Answer
Mode operation are covered in detail, as well as the handshaking procedures employed between
two modems in an auto-answer application.

Chapter 5 - AT Command Mode Operation

Chapter 5 may be the most important chapter of this manual. It begins with an introduction and
discussion on Command Mode fundamentals. A flow chart is provided to illustrate Command
Mode and On-Line Mode operation and the methods used in each mode. Next, there is a
summary of the modem’s commands and responses. We then go into a detailed explanation of
each modem command, providing examples where applicable.

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6

Chapter 1 - Introduction and Description

Chapter 6 - S-Registers

Chapter 6 covers the modem's S-Registers, which enable the user to establish, read, and modify
various modem options. All of the S-Registers are charted and explained, followed by instructions on
accessing the S-Registers and reading or changing their values.

Chapter 7 - Callback and Remote Configuration

Chapter 7 documents instructions on how to operate the modem's Callback and Remote
Configuration features; and the usage of LOGIN Passwords, Set-Up Passwords and Remote Escape
Characters as network management tools.

Chapter 8 - DIP-Switches

Chapter 8 covers the modem’s printed-circuit board options. Sixteen DIP-Switch settings and the
modem's speaker volume control are explained in detail, including all default settings.

Chapter 9 - Warranty, Service & Technical Support

Chapter 9 provides statements on your five-year warranty, instructions for getting modems serviced
at the factory and the procedure for downloading firmware upgrades via FlashROM.

Appendixes

There are also several appendices at the end of this manual, most of which repeat information
contained in the chapters, but in a more condensed form. These appendices can be used as a quick
reference.

Appendix A - Upgrading Your Modem’s Firmware
Appendix B - Troubleshooting
Appendix C - AT Command Summary
Appendix D - V.25bis Operation
Appendix E - Cabling Diagrams
Appendix F - Regulatory Information

1.3 Modem Features

The MultiModem BA/BL Series modem connections can be made on Public Switched Telephone
Networks (PSTNs) and/or point-to-point 2-wire or 4-wire (BL only) telephone type circuits.

Your modem offers interactive automatic dialing, as well as Command Mode option configuration.
You may store up to ten command line/telephone numbers, of up to 60 characters each, in the
modem’s nonvolatile memory. The modem pulse or tone dials, and recognizes dial tones and busy
signals for reliable call-progress detection. The modem can detect AT&T calling card tones. It is
FCC-Registered for connection to telephone networks without any Data Access Arrangements
(DAA’s).

Your modem also features Callback Security to protect networks from unauthorized use, and to
manage phone line costs. By using the modem’s phone number and password directory, a host site
can, upon receipt of a call, callback to a remote site at a predetermined number.

Remote Configuration permits you to assist users at remote sites, saving you the time and trouble of
site visits and preventing misinterpretation of configuration instructions.

Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide

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1.3.1 MT2834BA/BL Series Features

Your MT2834BA/BL modem meets the proposed Enhanced V.34 ITU standard for data signalling
rates as high as 33.6/31.2K bps in full duplex mode. Enhanced V.34 is an extension of V.32/V.32bis/
V34 standards, and supports and is compatible with those features, including EIA extended
Automode; adaptive line probing; automatic symbol rate and carrier frequency during start-up; and
retrain and rate renegotiation (in 2400 bps increments).

The major application for the MT2834BL is in 4-wire leased line networks with the addition of dial
backup capability. With this capability, the dial-up feature saves any down time if the leased line fails.
Since the MT2834BL operates according to ITU V.34 modulation, it can operate full-duplex over two
wires, so that the dial backup mode performs the same throughput as the leased line.

The MT2834BA/BL features ITU V.25bis standard for synchronous dialing, ITU V.42 error correction
and V.42bis data compression, providing 100% error-free data transmission. V.42 error correction
incorporates MNP( Classes 3 and 4, and LAP-M. You may select V.42bis data compression for 4-1
throughput, or MNP Class 5 for 2-1 throughput.)

1.4 Fax Features

Your modem meets the ITU V.17 standard for sending and receiving faxes. When linked to a
compatible fax machine or modem, it can transmit faxes at 14,4 K bps. It also meets the ITU’s Group
3 Designation for sending and receiving faxes at 9600 bps; and Group 2 Designation for sending and
receiving faxes at 4800 bps. The modem is also downward-compatible with modems to speeds as
low as 300 bps, so it can send and receive faxes with any fax machine in the world.

Chapter 1 - Introduction and Description

Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide

8

1.5 Technical Specifications

Your data/fax modem meets the specifications listed below:

Tradename MultiModem Model Numbers MT2834BA, MT2834BAI, MT2834BL, MT2834BLI

Data Rates (modem) 33,600, 31,200, 28,800, 26,400, 24,000, 21,600, 19,200, 16,800,

14,400, 12,000, 9600, 7200, 4800, 2400, 1200, 0-300 bps

Data Rates (fax) 14,400, 9600, 7200, 4800 bps Data Format Serial, binary, asynchronous at 0-300, 1200, 2400, 4800, 7200,

9600, 12,000, 14,400, 16,800, 19,200, 21,600, 24,000, 26,400,
28,800, 31,200, 33,600 bps; synchronous at 1200, 2400, 4800,
7200, 9600, 12,000, 14,400, 16,800, 19,200, 21,600, 24,000, 26,400,
28,800, 31,200, 33,600 bps

Compatibility ITU V.42bis, V.42, V.34, AT&T V.32terbo, ITU V.32bis, V.32, V.21*,

V.22bis, V.22, V.23*,V.25bis, *Bell 212A and 103/113, V.17, Group 3
T.4, T.30 and EIA TR-29 Class 2 (*Bell 212A and 103/113 domestic
models only; *V.21/V.23 Int'l models only)

Chapter 1 - Introduction and Description

IITM

Error Correction V.42 (LAP-M or MNP 3 & 4) error correction Data Compression V.42bis, (4:1 throughput) or MNP 5 (2:1 throughput) data

compression

Speed Conversion Serial port data rates adjustable to 300, 1200, 2400, 4800, 9600,

19,200, 38,400, 57,600 and 115,200 bps

Flow Control Options Xon/Xoff, Hardware RTS/CTS, ENQ/ACK, Unix-to-Unix Copy

Protocol (UUCP) "Spoofing"

Mode of Operation Full duplex over both dial-up lines and 2-wire or 4-wire (BL only)

leased lines; automatic or manual dialing, automatic or manual
answer; For BL only: auto dial backup on separate lines in leased­line operation

Intelligent Features Fully “AT command” compatible, microprocessor controlled remote

configuration, EIA extended Automode, adaptive line probing,
automatic symbol rate and carrier frequency during start-up, retrain
and rate renegotiation, autodial, redial, repeat dial, dial linking, pulse
or tone dial, dial tone detection, dial pauses, call status display, auto­parity and data rate selection, keyboard-controlled modem options,
nonvolatile memory and on-screen displays for modem option
parameters and up to ten telephone numbers/command lines of up
to 60 digits each, help menus

Command Buffer 60 characters Modulation Trellis Coded Modulation (TCM) at 33,600, 31,200, 28,800, 26,400,

24,000, 21,600, 19,200, 16,800, 14,400, 12,000 and 9600 bps,
Quadrature Amplitude Modulation (QAM) at 9600 (non-trellis), 4800
and 2400 bps, PSK at 1200 bps, FSK at 300 bps

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Chapter 1 - Introduction and Description

Fax Modulations V.21CH2 FSK at 300 bps, V.27ter DPSK at 4800 and 2400 bps,

V.29 QAM at 9600 and 7200 bps, V.17 TCM at 14400, 12000, 9600,
and 7200 bps

Transmit Level -11dBm (dial-up), -9 or -15 dBm (leased-line); dBm level selectable

with DIP-Switch #3 in leased line setting

Frequency Stability ±0.01% Connectors One DB-25 RS-232C connector; two RJ11 (three for BL) for phone

line/telephone set; power.

Diagnostics Power-on Self Test, Local Analog Loop, Local Digital Loop, Remote

Digital Loop, Back-to-Back Test.

Indicators LEDs for Transmit Data, Receive Data, Carrier Detect, Speed

Indicators, Off Hook, Terminal Ready, Error Correction, Fax, and
Error

Controls Toggle switches for Voice/Data with Originate or Answer, Power On/

Off; and DIP Switches for various modem options.

Speaker Speaker for call progress monitoring Operating Temperature 0° to 50° C (32° to 120° F) Power Requirements 115 Volts AC, 60Hz, 0.3amp (2-prong outlet-mounted transformer)

Dimensions 6.150" x 9.00" x 1.375"

Weight 1.6 pounds/0.72 Kg (without transformer)

Limited Warranty Five Years

1.6 Power

Power is supplied through an AC power transformer terminated with a standard two-prong plug. The
transformer supplies low voltage AC to the modem, and plugs into any conventional 115 volt AC, 60
Hz, two-prong power outlet (240 volts AC, 50Hz, .3 Amp for International modems). The power
transformer supplied with the modem is the only one that should be used. Use of any other
transformer could cause damage to the modem. A Power On/Off switch is located on the back of the
modem.

240V/50Hz optional (International).

15.6 cm x 22.9 cm x 3.5 cm

2.6 pounds/1.18Kg (with transformer)

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1.7 Modem LED Indicators

The MultiModem diagnostic LED indicators are shown in Figure 1-1 and Figure 1-2.

Chapter 1 - Introduction and Description

Answ

Orig

Voice/
Data

SD

Send

RD

Rcv

CD

Carr

28.8K

24.028.8

24.0K

19.2

19.2K

14.4

14.4K

96

9600

24

2400

OH

Off Hk

TR

Rdy

EC

V.42

FX

Fax

MT2834BA
Series
Intelligent
Modem

Figure 1-1. MT2834BA LED Display

Figure 1-2. MT2834BL LED Display

(SD) Send (Transmit) Data. This LED blinks when data is being transmitted, on for a space, off for a

mark. The state of this LED matches the TD circuit on Pin 2 of the RS-232C/V.24 interface.
(RD) Receive Data. This LED blinks when data is being received, on for a space, off for a mark. The

state of this LED matches that of the RD circuit on Pin 3 of the RS-232C/V.24 interface.
(CD) Carrier Detect. This LED is lit when a valid carrier tone has been detected.

When the modem is connected at 33,600 bps, the 28.8 LED rapidly blinks at approximately 5 blinks
per second. When the modem is connected at 31,200 bps, the 28.8 LED blinks slowly at
approximately 1 blink per second.

(28.8) 28,800 bps. This LED is lit when the modem is connected at 28,800 bps. Note: if the modem
falls back to 26.4K bps while in V.34 mode, both the 28.8 and 24.0 LEDs light.

(24.0) 24,000 bps. This LED is lit when the modem is connected at 24,000 bps. Note: if the modem
falls back to 21.6K bps while in V.34 mode, both the 24.0 and 19.2 LEDs light.

(19.2) 19,200 bps. This LED is lit when the modem is connected at 19,200 bps.
(14.4) 14,400 bps. (2834 and 1432 models only) This LED is lit when the modem is connected at

14,400 bps. Note: if the modem falls back to 12,000 bps while in V.32bis mode, both the 14.4 and 96
LEDs light.

(96) 9600 bps. This LED is lit when the modem is connected at 9600 bps.
(24) 2400 bps. This LED is lit when the modem is connected at 2400 bps.
(OH) Off Hook. This LED is lit when the phone line is "off hook". This occurs when the modem is

dialing, on-line, or answering a call. This LED also flashes when the modem is pulse dialing in
Command mode.

(TR) Terminal Ready. When the TR LED is lit, the modem is permitted to answer an incoming call.
When it goes off, a connected modem will disconnect. The state of the TR LED matches that of the
DTR circuit on Pin 20 of the RS-232C/V.24 interface.

(EC) Error Correction. This LED is lit when the modem is set for V.42 error correction, and flashes on
and off when data compression is activated.

(FX) FAX. This LED is lit when the modem is connected in FAX mode.
(ERR) ERROR. When this LED is lit, either the leased line is down and the modem is in dial backup

mode, or else the self-test has failed.

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1.8 Controls on PC Board

The MultiModem is designed on a single printed circuit (PC) board. This board contains one 16­position DIP-Switch (numbered 1-16). The DIP-Switches are accessible through a cut-out on the side
of the modem. There is also a knob which is used to adjust the speaker volume. This knob is
accessible through the modem's rear panel. The sixteen DIP-Switches control various modem
options or set default values for Command Mode operation. There is a difference in how several of
the switches operate depending on whether you are in synchronous or asynchronous mode. Refer to
the switch label on the bottom of the modem for an exact list of the switch functions in asynchronous
and synchronous operation. Chapter 8 provides detailed instruction for configuring the modem’s PC
board.

Chapter 1 - Introduction and Description

Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide

12

Chapter 2 - Installation and Connection

2.1 What Is in Your Modem Package?

Your MultiModem is made up of many components. Make sure you have them all before trying to
operate your modem. Your package should include:

· MT2834BA or MT2834BL data/fax modem

· RJ-11 telephone cord or BS-6312 plug (UK models)

· AC Power Transformer

· One Quick Start Guide

· One MT2834BA/BL CD. This CD contains PhoneTools

software program), the User Guide, and Adobe Acrobat Reader.

If any item is missing, contact Tech Support.

2.2 Installation

The installation of the modem consists of making the physical connections necessary to render the
modem functional with your computer.

2.2.1 Safety Warnings

Chapter 2 - Installation and Connection

TM

( a data communications and fax

1. Use this product only with UL and cUL listed computers.

2. To reduce the risk of fire, use only 26 AWG (.41mm) or larger telephone wiring.

3. Never install telephone wiring during a lightning storm.

4. Never install a telephone jack in wet locations unless the jack is specifically designed for wet
locations.

5. Never touch uninsulated telephone wires or terminals unless the telephone line has been
disconnected at the network interface.

6. Use caution when installing or modifying telephone lines.

7. Avoid using a telephone during an electrical storm. There is a risk of electrical shock from
lightning.

8. Do not use a telephone in the vicinity of a gas leak.

2.2.2 Installation Procedure

The following procedures will guide you through the physical connections required to make your
modem operational. Software loading is covered later in this guide.

1. Verify that the settings for DIP-Switch #5 and DIP-Switch #10 match those of your system
configuration.

The 16-position DIP-Switch (numbered 1-16) is accessible through a cut-out on the right side (as
the LEDs are facing you) of the modem chassis. For a full description of all DIP-Switch Settings,
refer to Chapter 7.

DIP-Switch Condition Effect

#5 UP* Selects Answer mode

DOWN Selects Originate mode

#10 UP* Selects Dial-Up operation

DOWN Selects Lease Line operation

* Factory Default setting

Multi-Tech Systems, Inc. MT2834BA/BL Series User Guide

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Chapter 2 - Installation and Connection

2. Verify that the ON/OFF switch at the rear of the modem to the OFF (Down) position.

3. For BA: Connect the modem to a dial-up line by attaching the RJ-11 telephone cord (provided
with your unit) to the LINE connector on the modem and to a dial-up wall jack.

PHONE LINE

VOLUME

EIA RS232C

ON

OFF

POWER

Figure 2-1. MultiModemBA Connections

The LINE connector can be used for a dial-up connection or a 2-wire leased-line connection.

3. For BL: Connect the modem to either a dial-up line or lease-line.
To connect the modem to a dial-up phone line, attach the RJ-11 telephone cord (provided with
your unit) to the PSTN connector on the modem and to a dial-up wall jack.

To connect the modem to a leased line, attach the RJ-11 telephone cord (provided with your unit)
to the LEASE connector on the modem and to a leased line wall-jack.

PHONE PSTN

LEASE

VOLUME

EIA RS232C

OFF

POWER

ON

Figure 2-2. BL Connections

The PSTN connector is used for a dial-up connection.

The LEASE connector can be used for a 2-wire or 4-wire leased-line connection.

4. Attach the EIA RS-232C connector on the modem to the serial port on your computer or terminal
with an RS-232 (or V.24) cable (you supply).

5. To connect a telephone set to the modem (optional) plug one end of an RJ-11 phone cord into
the PHONE connector on the modem, and plug the other end into your telephone.

6. Attach the AC Power transformer provided with your unit to the POWER connector on the
modem and to a live AC outlet.

Note: Only apply power to the modem using the power transformer provided with your unit. Use
of a power supply not designed for your unit could result in damage to your modem and will void
the warranty.

7. Apply power to the unit by setting the ON/OFF switch at the rear of the modem to the ON (Up)
position.

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Chapter 2 - Installation and Connection

2.3 Installing PhoneTools, the Data Communications Software

Data communications software is designed to send and receive messages. Multi-Tech includes a
data communications software program, PhoneTools, with your modem. However, the modem will
work with any data communications software.

To install PhoneTools, insert the MT2834BA/BL CD in you CD-ROM drive and click the PhoneTools
icon. You will be asked to choose your language. The software will then automatically load onto your
PC.

2.4 Is Your Modem Ready for Use?

As soon as you have connected power to the modem, if you are an experienced modem user, you
may simply want to check your modem’s settings for data compression, error correction, and so on.
You may find that you can get moving quite quickly if you just issue an ATL5, ATL6 and an ATL7
command. These commands list how your modem is currently configured. If you come across a
setting you’re unsure of, refer to Chapters 5 and 6 of the User Guide for AT command and S-Register
explanations and defaults.

If you’re a novice, refer to Chapter 3 of the User Guide to learn about the basics of data
communications.

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Chapter 3 - Software Configuration and Modem Basics

3.1 Introduction

Chapter 2 described the installation of PhoneTools, a communications software. If you are using a
different software package, there are some points you should take into consideration. Since your
communications software configuration is affected by the capabilities of your computer, this chapter
begins with a discussion of the limitations of some serial ports and how to identify them. It then
discusses communications configuration in general and recommends settings specifically for the
MultiModem. The last section of this chapter walks you through the basics of using your modem.

3.2 Configuring Your Software

Communications software must be configured to work with your modem, your computer, and the
remote system it is calling. Fortunately, most communications programs make the process easy by
providing a default initialization string for your modem as well as defaults for most of the other
required parameters.

3.2.1 Configuring Software for Your Modem

Because remote computers may have different connection requirements such as speed, number of
bits, parity, log-on sequences, etc., communications software is typically configured by sessions,
each session having a unique configuration for a given connection. Most communications programs,
however, have a separate modem configuration menu because modem configurations rarely change
from session to session.

Chapter 3 - Software Configuration

The most important configuration is the modem initialization string. This is a sequence of commands
the software uses to configure the modem when the communications software is loaded or when a
session begins. Always begin the initialization string with the ATtention command AT, then follow it
with the modem reset command, &F. Issuing a reset command before other commands ensures that
you are starting with a known state.

The rest of the commands in the initialization string depend on the capabilities of the modem and
what you want it to do. Some older communications programs require you to create the initialization
string by yourself. Most modern communications programs, however, provide you with a ready-made
initialization string that is automatically selected when you choose your modem model from a list. It is
a poor idea to use an initialization string intended for another modem, especially one from another
manufacturer, because modem capabilities and command implementations vary from modem to
modem. However, if your MultiModem does not appear on a modem list, you may use the
MultiModemII initialization string.

3.3 PC Initialization Strings

We recommend the following initialization string for a MultiModem connected to a PC-compatible
computer when sharing a line with a telephone:

AT &F X4 S0=0 ^M

This string resets the modem to the factory default settings, selects extended result codes with NO
DIAL TONE and BUSY, and turns off auto-answer. ^M must end every string sent to the modem from

software. It is the ASCII code for the RETURN key on most keyboards, and the default code for the
carriage return character in the modem and most communications programs. The carriage return
character is defined in the modem in S-register S3; if you change it, you must also change the
carriage return character code used in your communications software. If you send a command
directly to the modem in terminal mode rather than indirectly through communications software, you
must end the command string by pressing the RETURN key (<CR>) instead of adding ^M to the
string.

The following initialization string is for a MultiModem on a telephone line that functions solely as a
DATA LINE:

AT &F X4 S0= 2 ^M

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Chapter 3 - Software Configuration

3.3.1 Changing Default Parameters

By default, the modem will answer after the first ring and try to communicate with a modem on the
other end of the line. If you have one telephone line for voice, fax, and modem communications, the
modem may attempt to answer all incoming calls, voice as well as data. To change auto-answer to
default off, open your communications program and type the following string in the terminal window:

AT &F S0=0 &F9 &W0 <CR>

This string selects the factory default parameters, then turns auto-answer off and stores that setting,
along with all other current parameters, in nonvolatile memory. The &F9 command causes the
modem to load the values from nonvolatile memory the next time it receives the &F command. You
will use the same initialization string as before:

AT &F X4 ^M

But now the modem will load the values stored in nonvolatile memory when you turn on the modem
and when you issue the ATZ or AT&F reset commands.

Note: Because it clears the command buffer, you should not use ATZ in an initialization string.

3.3.2 Other Parameters

The default values for the other parameters in modem configuration menus rarely need changing.
They typically include the dialing prefix (ATDT for touch-tone service and ATDP for rotary service),
the dialing suffix (^M), the hang-up string (+++ATH0^M), and response messages (RING, NO
CARRIER, BUSY, etc.). Communications software with a host mode might also include an auto­answer string (AT S0=1^M).

3.4 Configuring Software for Your Computer

You must configure your communications software to match your computer’s configuration. If the
modem is connected to the COM2 serial port, you must tell the software you are using COM2.
Another important parameter is the serial port baud rate. This is the speed at which your modem
communicates with your computer, not the speed at which your modem communicates with another
modem. When V.42bis data compression is enabled, you must have a serial port baud rate four
times the transmission speed of the modem to fully optimize compression.

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3.5 Modem Basics

You control your modem by issuing AT commands, setting S-Registers, and setting DIP-Switches.
You can easily change the settings of your DIP-Switches, as they are located on the right side of
your modem’s chassis. Right now your modem is set up for the most typical user application, that is,
as a traditional modem set to make a dial-up call to a remote installation where the call is answered
automatically; therefore, you shouldn’t need to change the DIP-Switches. (If however, you know that
your application does not follow this profile, please refer to Chapter 8 for full details on DIP-Switch
settings.)

While you may operate your modem manually, it is more likely that you will use your data
communications software to either:

• enter “terminal” mode, where you can “speak most directly” to the modem by issuing AT
commands, or to

• launch a datacomm session through a set of modem configurations which you select and then
associate with a target telephone number. Once you have created, saved, and named this set of
information according to your connection needs and your datacomm software’s conventions, the
software then simplifies your dialing because you needn’t re-configure your modem, nor run the
risk of mistakenly keying-in incorrect information.

Either way, you need to understand that an AT command is the method by which your modem is
controlled, and must therefore prefix nearly all commands. AT stands for attention, and alerts the
modem that a command follows. You may enter these commands with either upper- or lowercase
characters. Entering AT automatically sets the modem’s serial baud rate to match your computer’s
and also sets the modem’s parity. It also clears the modem’s command buffer.

Chapter 3 - Software Configuration

Once you’re in terminal mode, enter AT followed by <CR> to check whether your modem is
operational. If everything’s fine, your modem will respond OK. (Note: refer to Chapter 4 for additional
details on Dialing, Automatic Answering, Dial Back-Up and Automatic Leased Line Restoral.)

3.5.1 Simple Operations

You can dial a number by using the ATD command and the phone number of the modem with which
you wish to connect, e.g., ATD6127853500. Your modem will dial the number, and hear a
“scrambling” noise as the modem negotiates the kind of connection it can make, and once the
modems have settled on a common connection, you will receive a connect message on your
computer’s video display. As the modem dials and connects, you may notice changes across its front
LED panel: the OH (Off Hook) LED lights to let you know the modem is operating as if you had
picked up the handset to a phone. The CD (Carrier Detect) LED lights to let you know the modem
has detected a device it can connect to. A speed LED lights to let you know at which speed the
connection has been made.

To hang up a call, enter +++ATH<CR>. Your modem will return on hook, just as if you had returned a
phone’s handset to its cradle. Notice also that the OH, CD and speed LED’s are no longer lit. Your
video now displays OK, signifying that your modem is ready for your next command.

3.6 The Answer/Originate - Voice/Data Toggle Switch

Located on the front of the modem is a Voice/Data "toggle" switch with Originate/Answer capabilities.
This switch enables the modem to automatically dial a phone number stored in the N1 location of
memory whenever this switch is toggled. (Note that you must first enter AT$VD1&W0<CR>. This
command string enables Voice/Data dialing when the Voice/Data toggle switch is activated.)

If you are "Manually" dialing with an attached telephone device (and not with your keyboard), your
modem originates when toggled in that position (DOWN); and if you are "Manually" answering
(modem is not configured to automatically answer via S-Register S0 setup), the modem answers an
incoming call when toggled in that position (UP).

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Chapter 4 - Manual Dial and Automatic Answer

4.1 Introduction

We’ll assume that yours is the very common application, where you are using a modem to dial up a
remote computer. The modem has been factory preset for originating a call to a compatible 33,600
bps modem (also set up for hardware flow control, V.42 error correction, V.42bis data compression
and CTS/RTS operation). If the answering modem is not set up similarly, the modem automatically
adjusts to the appropriate protocol.

4.2 Dialing/On-Line/Answering

There are several basic steps for “originating” and “answering” in data communication mode:

1. Load communication software

2. Dial

3. Establish On-Line connection

4. Terminate Call

A simple way to dial is from the keyboard of your computer or terminal. You enter a command on the
keyboard to tell the modem to dial.

If you use a sophisticated communications software package, the software tells you to enter phone
numbers and other information. If this is the case, the software, and not you, gives the dialing
commands to the modem. All of the commands, option registers and intelligent features of the
modem is taken care of by the software.

Chapter 4 - Manual Dial and Automatic Answer

If you are giving commands directly to your modem (and not through your software), each command
must begin with AT (ATtention Characters). AT characters may be entered in upper or lower case.

Entering AT automatically sets the modem’s speed to match the speed of the computer or terminal,
and also sets the modem’s parity.

The AT characters alert the modem that a command follows. The AT Command can also be used to
clear the command buffer, by simply typing AT and hitting RETURN.

The letter D in a command causes the modem to dial the numbers immediately following it (e.g.,
ATD6127853500). You have a choice of either pulse (ATDP) or tone (ATDT) dialing methods.

The modem responds with “CONNECT” on your video display after the number is dialed and a
connection signal is detected. The modem is now in “On-Line” mode, and is ready to communicate
with a host site.

If no connection signal is detected within 45 seconds (this time period can be adjusted by S-Register
S7), the modem goes On Hook/hangs up and returns to Command mode. At this point, your video
displays “NO CARRIER”.

Enter +++ATH to Hang Up On-Line (bring modem on-hook), and terminate the modem's On-Line
mode. At this point, your video displays “OK”.

In addition to the call originating capabilities, the modem can also automatically answer incoming
calls. You need not be present. You can, however, control the situation by configuring the modem to
either answer or not to answer, or to answer after a specified number of rings. This is done by setting
the value of S-Register S0 (modem defaults to automatically answer an incoming call after one ring).
Refer to Chapter 6 for S-Register details.

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Chapter 4 - Manual Dial and Automatic Answer

4.3 Automatic Leased Line Restoral Operation

When the modem is in Dial Backup mode, it periodically checks the leased line to see if it's
operational and tries to restore the leased line if possible. S-Register S18 determines how often
restoral attempts occur. The default for S18 is 30 minutes, and can be set in one minute increments
from 10 to 255 minutes. Setting the restoral attempts under 10 minutes causes excessive breaks in
the dial-up operation.

Note: both local and remote modems must have S-Register S18 set identically. Refer to Chapter 6
for more information on S-Register S18.

4.4 Manual Dial Backup Call Termination

With your modem in leased line mode (DIP-Switch #10 in the DOWN position) and with dial backup
operation in process, there are two ways to manually terminate the dial backup call (other than
automatic leased line restoral). In each case, you will try to establish the leased line connection
because it is back in operating condition. The methods of dial backup call termination are:

1) Manual Control. The "Voice/Data" switch can be used to change from a dial back line to leased
line by toggling down once. When that is done, the modem tries the leased line connection, and,
if it is good, the modem disconnects the dial back call and establishes a leased line connection.

2) DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a
disconnect occurs. This is probably the most common method used by computer systems at the
automatic answer end of the line to cause the answering modem to disconnect after toggling off
procedures.

4.5 Dial Backup and Leased Line Restoral

The dialing associated with the MultiModem, when in leased line with dial-back mode, involves
placing a call from the originating modem due to a leased line failure.

After a preset period of time (determined by S-Register S18), the modem automatically tries to
restore the leased line.

The parameters used to determine if a leased line is down (so automatic dial back can occur), is
based on the modem doing a “retrain” on the leased line due to an error condition in the transmission.
An error condition is defined as a "hit" on the line (the Carrier gets interrupted).

The retrain is a "handshake" procedure between the modems to establish the Carrier again. If the retrain fails, both modems (originate and answer modems) start their Dial-back timers. The time is determined by S-Register S19 settings. The S19 default setting is one minute. During that minute, the originate modem tries to establish the leased line link. If the leased line is established during that time, the timer is cleared and everything is back to normal. If the timer expires, the modems goes to dial-back mode.

The purpose of the timer for the Answer modem is to determine when it accepts a dial-up call. When
both timers have expired and the leased line has not been established, the dial-back procedure
starts. The number dialed is the one stored in location N9 of the originate modem's phone number
memory. In the preparation for proper dial-back operation, enter the proper number in the N9 location
using the commands detailed in Chapter 5. Keep in mind that the number also can be dialed in
V.25bis Command mode.

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4.6 Dial-Up Operation

When your modem is used as a dial-up modem (DIP-Switch #10 in the UP position), it can both
originate and answer calls. To originate calls, you use the automatic dialing capability of the modem's
Command mode.

To do this, use the computer or terminal keyboard to enter a few command letters, followed by the
phone number you wish to dial. If you have a computer with sophisticated communications software,
you may end up talking back and forth with the software, and the software will take care of talking to
the modem.

It is still possible, however, to dial your data calls using a telephone set. There are few reasons why
you would want to do this, but if you have a need to use the telephone set to dial, we explain how in
the next section. We will delay our coverage of Command Mode autodialing, and all other Command
Mode features, until Chapter 5.

4.7 Manual Call Origination

You can use the modem to both originate and answer calls. To originate calls in Asynchronous mode,
you will most likely use the modem's Command mode, and give the modem automatic dialing
commands (we will delay our discussion of the Command mode until Chapter 5). When using your
modem in Synchronous mode, the Command mode is disabled, so you must automatically dial your
calls with a telephone set. To use manual dialing, you first connect an ordinary telephone set (either
touch tone or rotary dial) to the modem's PHONE Jack, if you have not already done so. Next, set the
speed selection, (DIP-Switches #13 and #14), to the speed at which you wish to communicate.
These DIP-Switches are located on the side of the modem. (Refer to Chapter 8 for DIP-Switch
settings.) Your computer or terminal may be set for up to 115,200 bps.

Chapter 4 - Manual Dial and Automatic Answer

When your telephone set is connected, you can use it to dial the modem you wish to call. Simply dial
the number, and then listen to the dialed modem's answer tone. When you hear it, press the Voice/
Data switch on the front of the modem down (to the Originate position). You don't have to hold it
down. Just "toggle it" (press it once and let it go). Once you press the switch, the tone you hear
should change to another pitch, or change into a rough-sounding scrambled noise. You then replace
the telephone handset in its cradle, and your data communications begins.

Note that the modem may call manually via the keyboard command ATD, or by pressing the Voice/
Data switch on the modem's front panel downward. To force the modem to automatically answer
calls, either type ATA, or press the Voice/Data switch on the modem's front panel upward.

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4.8 Automatic Answering

The modem can be used as an automatic answering modem. No special modifications or settings are
required other than making sure that the Auto-Answer select switch is set to Auto-answer enabled
(DIP-Switch #5 UP).

The modem, when in its idle state, is set for Originate mode frequencies. An incoming ring signal
automatically switches the modem into Answer mode.

You can program the modem to answer a call after a certain number of rings using S-Register S0
(see Chapter 6). Refer to Section 4.10 for the handshaking procedures used by the modem when in
automatic answer mode.

In many originate-only applications, you may wish to disable the automatic answer capability of the
modem. If a telephone set is connected to the modem, you may wish to receive incoming calls in a
voice mode for normal voice conversation. If auto-answer is not disabled, all incoming calls are
answered by the modem, preventing voice communications. To disable automatic answer, place DIP­Switch #5 to the DOWN (Disable Auto Answer) position (refer to Chapter 9).

Another way to disable automatic answer is to use S-Register S0 to configure the modem to answer
on the nth ring, where n equals zero (0). Another alternative is to have the modem answer after five
or six rings, which gives you time to answer it manually if you wish. (See Chapter 6 for S-Register
information.)

Chapter 4 - Manual Dial and Automatic Answer

4.9 Manual Answering

We have shown that the modem can automatically answer incoming calls. The MultiModem can also
answer manually, under your control. The most typical application involves you and another person,
who, after carrying on a voice conversation, want to convert to data communications between your
modems without having to hang up and dial again.

The problem here is that both modems are in originate mode. For two modems to communicate, one
of them must be in originate mode and the other must be in answer mode. The solution here is to
force either one of the two modems to Answer mode, and the other to Originate mode.

The modem can be forced into either Answer mode or Originate mode by using the Voice/Data
switch on the front of the modem.

In our example, let's say that you and your friend Bill have just had a voice conversation. Both of you
have your telephones connected to your modems, and your modems are connected to computers or
terminals. Set the speed switches to the proper speed on both modems. To switch to Data mode
from Voice mode, you would switch the Voice/Data switch Down (to the Originate position), and Bill
would switch his up to Answer. This switches your modem to the originate on-line mode, and Bill's to
the Answer on-line mode. You would both then hang up your telephone handsets, and continue the
conversation via your keyboards.

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4.10 Handshaking Details

This section briefly explains what happens between two modems in a normal call. We are assuming
that there are MultiModems at both the originating and at the answering end of the telephone line. (If
other brands of modems are used with our modems, they will still communicate, but each
manufacturer tends to use slightly different delay timings and sequences, and many of the brands
vary in their LED designations.)

When a call is dialed from the originating modem, the called modem responds to the ringing by
switching into Answer mode and by turning on its RI (Ring Indicator, RS-232C/V.24 Pin 22) signal as
the rings are detected.

Note that in order for the called modem to be able to answer the call, it must have a high DTR (Data
Terminal Ready) signal. This signal comes from the computer or terminal to which it is attached, on
RS-232C Pin 20.

When the called modem answers the call, its OH (Off Hook) circuit comes on and the ringing stops.
Two seconds after the call is answered, the called modem begins transmitting its answerback tone.

The originating modem, which has been off hook and waiting for the answerback tone, turns on its
transmitter when it hears the tone. Then after a one second delay, the orignating modem's CD
(Carrier Detect) comes on.

The called modem then responds to the originating modem by turning on its CD (Carrier Detect)
signal, and the handshaking is completed.

Chapter 4 - Manual Dial and Automatic Answer

Note: With the modem in Reliable or Auto-Reliable mode, some additional handshaking takes place.

This is explained in Section 5.4.8.

4.11 Call Termination

There are a number of ways to terminate a call, or simply stated, hang up. They are:

1) Command Mode Control. To terminate a call by Command Mode, enter +++ATH then
RETURN; or, send a BREAK signal followed by ATH and a RETURN.

2) DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a
disconnect occurs. This is probably the most common method used by computer systems at the
automatic answer end of the line to cause the answering modem to disconnect after logging off
procedures.

3) Loss of Carrier. After a data connection is established, the modem disconnects if a loss of
carrier occurs for 700 milliseconds (0.7 seconds) or more. Note that one cause of carrier loss
would be if one of the modems disconnect normally.

4) Abort Timer.
Answer Mode: When OH (Off Hook) comes on, the called modem starts a forty-five-second

timer and waits for a carrier signal from the originating modem. If carrier is not detected within
this period, the modem disconnects (hangs up) and is ready for another call.

Originate Mode: The abort timer functions the same as in answer mode, except that the timer
begins after the modem has completed dialing, instead of when it first goes off hook. It is possible
to change this forty-five second wait period to any other value (from 0 seconds up to 255
seconds), or to disable the timer completely by re-configuring S-Register S7 (see Chapter 6).

5) Inactivity Timer. Causes the modem to disconnect if no data is transmitted or received for a
specified time. The timer is restored any time a character is passed through the serial port in
either a send or receive state. This timer runs in both normal or reliable connections and is
controlled by S-Register S30. The Inactivity Timer can be disabled by setting S30 to 0, which is
the factory default setting.

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Chapter 5 - Command Mode

5.1 Introduction

AT commands are the means by which you, and your communications software, are able to
communicate with and configure your modem. They enable you to establish, read, and modify
parameters in addition to dialing. The following provides both a summary and a detailed explanation
of the AT commands recognized by the MultiModem.

5.1.1 AT Command Editing

The BACKSPACE key on your keyboard can be used to edit characters in the AT command line. An
AT command is not executed until the RETURN key is pressed. The BACKSPACE key erases the
previous character for reentering.

The BACKSPACE key does not erase the AT characters once they are entered. If your keyboard
has no BACKSPACE key, CTRL-H does the same thing. The character recognized by the modem
as BACKSPACE may be changed to any other ASCII character with S-Register S5.

If you wish to cancel an entire command that has been entered but not yet executed, enter CTRL-X.
This also clears the command buffer. The effect is the same as backspacing to cancel the entire
command, only quicker.

Characters entered in a command are stored in the modem's Command Buffer (memory) until
executed by hitting RETURN. The Command Buffer's capacity is sixty characters. The Attention
Characters AT do not count in the sixty allowed Command characters. Spaces, which may be used
for increased display readability, may be used when entering a command, but are not stored in the
Command Buffer and are not counted in the sixty allowed characters. Hyphens, parentheses, etc. are
not allowed.

Chapter 5 - Command Mode

If the sixty character limit is exceeded or if invalid characters are entered, the Command Buffer
automatically erases, and an ERROR message appears. You would then re-enter your command
within the sixty-character maximum, using only the allowed characters.

5.1.2 Functional Modes

The MultiModem can be in one of two functional states (see Figure 4-1). These are "Command mode" and "On-line mode". (There is also an in-between state, "Wait-for-Carrier", where the modem

is out of Command mode but not yet really On-Line.
When the modem is initially powered up, it is in Command mode and is ready to accept commands

from your keyboard or software. The modem enters On-line mode after dialing, making a connection
with another modem, and then detecting a valid carrier signal. If no carrier is detected within a certain
time frame, the modem abandons the call and re-enters Command mode.

Once on line, the modem exits On-line mode if one of two conditions is met. If the carrier is lost or
intentionally dropped, the modem hangs up and re-enters Command mode. Also, if the modem
recognizes the Escape sequence for which it is configured (i.e., either the Escape characters in the
serial data stream, the Remote Escape characters in the modulated data stream, or the Break
signal), the modem will exit On-line mode, retain the datacomm link, and enter Command mode.

You can force the modem into On-line mode without dialing by sending the ATD or ATA command to
the modem.

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Chapter 5 - Command Mode

COMMAND

HANG

UP

WAIT FOR

CARRIER

No carrier

detected

Carrier lost

Figure 5-1. Functional Modes

ON-LINE

5.2 Summary of AT Commands

A wide variety of autodial operations and modem options can be controlled when the modem is in
Command Mode. Remember, nearly all commands begin with AT.

+++AT

MODE

Dial (D or A) command,

or incoming phone call

Carrier detected

AT0 Command

MODE

These commands are organized into several functional groups. An alphabetical summary of
commands is provided in Appendix D.

HOW TO COMMANDS

DIAL D Dial

A: or : Continuous Redial
$D DTR Dialing
$VD Voice/Data Dialing
N Dial a Stored Number

MODIFY DIALING P/T Pulse/Tone Dialing
PROCEDURES &P Set Pulse Dial Ratios

, Automatic Pauses in dialing
Y Long Space Disconnect
W Wait for New Dial Tone

; Return to Command Mode After Dial

Command

R Reverse Mode of Operation
! Flash On Hook
$ AT&T "Calling Card" Tones
@ Quiet Answer

MEMORIZE PHONE
NUMBERS D...N Store Phone Numbers

NN Number Linking
L List Numbers Stored in Memory

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STORE MODEM &F Load Factory Defaults
CONFIGURATIONS &W Store Configuration & S-Register
AND DEFAULTS Parameters

Z Reset Modem
V Result Code Terse/Verbose
$SP UNIX/"Spoofing”
&M Synchronous/Asynchronous Mode Select
&X Synchronous Transmit Clock Select

CONFIGURE Q Result Codes Enable/Disable Response
COMMAND &Q Result Code Selection
RESPONSES E Echo Command Characters

V Result Code Terse/Verbose
X Result Code...Basic/Extended/Call Progress

CONDITION &G Guard Tones
PHONE LINE M Monitor Phone Line

&T Remote Digital Loop Signal
#T Enable/Disable Trellis Coded Modulation
B Bell/V.21 Tones
#F Fallback When On-Line
&CD Cleardown at Disconnect (2834 Series only)
#A Auto-Speed Detect

Chapter 5 - Command Mode

CONTROL RS232C &C Carrier Detect Control
INTERFACE &D Data Terminal Ready Control

&R Clear To Send Control
&S Data Set Ready Control
&RF CTS/RTS Control
&SF DSR/CD Control

CONFIGURE &E0 Normal Mode
ERROR &E1 Auto-Reliable Mode
CORRECTION &E2 Reliable Mode

#L0 Negotiate V.42 Mode During Handshake
#L1 MNP On/LAPM Off
#L2 LAPM On/MNP Off
#L3 Direct LAPM/Phase Out Handshake
$A Auto-Reliable Buffering
$F Enable/Disable Auto-Reliable Fallback Character
$R Retransmit Count
$E Error Correction at 300 bps

CONFIGURE &E3 Flow Control Disabled
FLOW CONTROL &E4 Hardware Flow Control

&E5 Xon/Xoff Modem-Initiated
&E6 Xon/Xoff Modem Responds/No Pass-Through
&E7 Xon/Xoff Modem Responds/Pass-Through Allowed
#X Send Single/Multiple Xoff Characters
&E8 Enq/Ack Off
&E9 Enq/Ack On
&E10 Normal Mode Modem Flow Control Off
&E11 Normal Mode Modem Flow Control On
&E12 Computer-Initiated/Off
&E13 Computer-Initiated/On
&BS Maximum Block Size
$EB 10/11 bit Asynchronous Format
#P Parity Selection

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