Toshiba V.90 User Manual

V.90 56K Internal Modem User’s Guide

TOSHIBA

C500-0601M2

FCC Notice “Declaration of Conformity
Information”

This equipment has been tested and found to comply with the limits for a Class B
digital device, pursuant to Part 15 of the FCC rules. These limits are designed to
provide reasonable protection against harmful interference in a residential
installation.

This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, it may cause harmful
interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or 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 receiver.

❖ Connect the equipment to 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.

ii

NOTE: Only peripherals complying with the FCC Class B limits may be
attached to this modem. Operation with non-compliant peripherals or
peripherals not recommended by Toshiba is likely to result in interference
to radio and TV reception. Changes or modifications made to this
equipment not expressly approved by Toshiba or parties authorized by
Toshiba could void the user’s authority to operate the equipment.

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

❖ This device may not cause harmful interference.

❖ This device must accept any interference received, including interference

that may cause undesired operation.

Contact:

Toshiba America Information Systems, Inc.
9740 Irvine Blvd.
Irvine, CA 92618-1697
[phone]

iii

Industry Canada Requirement

This Class B digital apparatus complies with Canadian ICES-003.

Cet appareil numérique de la classe B est conformé à la norme NMB-003 du
Canada.

Pursuant to FCC CFR 47, Part 68:

When you are ready to install or use the modem, call your local telephone
company and give them the following information:

❖ The telephone number of the line to which you will connect the modem

❖ The registration number that is located on the device

The FCC registration number of the modem will be found on either the
device which is to be installed, or, if already installed, on the bottom of the
computer outside of the main system label.

❖ The Ringer Equivalence Number (REN) of the modem can vary.

For the REN of your modem, refer to your computer’s us er’s guide.

The modem connects to the telephone line by means of a standard jack called the
USOC RJ11C.

Type of service

Your modem is designed to be used on standard-device telephone lines.
Connection to telephone company-provided coin service (central office
implemented systems) is prohibited. Connection to party lines service is subject
to state tariffs. If you have any questions about your telephone line, such as how
many pieces of equipment you can connect to it, the telephone company will
provide this information upon request.

Telephone company procedures

The goal of the telephone company is to provide you with the best service it can.
In order to do this, it may occasionally be necessary for them to make changes in
their equipment, operations, or procedures. If these changes might affect your
service or the operation of your equipment, the telephone company will give you
notice in writing to allow you to make any changes necessary to maintain
uninterrupted service.

If problems arise

If any of your telephone equipment is not operating properly, you should
immediately remove it from your telephone line, as it may cause harm to the
telephone network. If the telephone company notes a problem, they may
temporarily discontinue service. When practical, they will notify you in advance
of this disconnection. If advance notice is not feasible, you will be notified as
soon as possible. When you are notified, you will be given the opportunity to
correct the problem and informed of your right to file a complaint with the FCC.
In the event repairs are ever needed on your modem, they should be performed
by Toshiba Corporation or an authorized representative of Toshiba Corporation.

Disconnection

If you should ever decide to permanently disconnect your modem from its
present line, please call the telephone company and let them know of this change.

Fax branding

The Telephone Consumer Protection Act of 1991 makes it unlawful for any
person to use a computer or other electronic device to send any message via a
telephone fax machine unless such message clearly contains in a margin at the
top or bottom of each transmitted page or on the first page of the transmission, the
date and time it is sent and an identification of the business, other entity or
individual sending the message and the telephone number of the sending
machine or such business, other entity or individual.

In order to program this information into your fax modem, you should complete
the setup of your fax software before sending messages.

iv

Instructions for IC CS-03 certified equipment

1 NOTICE: The Industry Canada label identifies certified equipment. This

certification means that the equipment meets certain telecommunications
network protective, operational and safety requirements as prescribed in the
appropriate Terminal Equipment Technical Requirements document(s). The
Department does not guarantee the equipment will operate to the 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.

v

The customer should be aware that compliance with the above conditions
may not prevent degradation of service in some situations.

Repairs to certified equipment should be coordinated by a representative
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.

Users should ensure for their own protection 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 electric inspection authority, or
electrician, as appropriate.

2 The user’s guide of analog equipment must contain the equipment’s Ringer

Equivalence Number (REN) and an explanation notice similar to the
following:

The Ringer Equivalence Number (REN) of this device can vary.
For the REN number of your modem, refer to your computer’s user’s guide.

NOTICE: The Ringer Equivalence Number (REN) assigned to each
terminal device provides an indication of the maximum number of
terminals allowed to be connected to a telephone interface. The termination
on an interface may consist of any combination of devices subject only to
the requirement that the sum of the Ringer Equivalence Numbers of all the
devices does not exceed 5.

3 The standard connecting arrangement (telephone jack type) for this

equipment is jack type(s): USOC RJ11C.

Copyright

This user’s guide is copyrighted by Toshiba Corporation with all rights reserved.
Under the copyright laws, this user’s guide cannot be reproduced in any form
without the prior written permission of Toshiba. No patent liability is assumed,
however, with respect to the use of the information contained herein.

© 2000 by Toshiba Corporation. All rights reserved.

Export Administration Regulation

This document contains technical data that may be controlled under the U.S.
Export Administration Regulations, and may be subject to the approval of the
U.S. Department of Commerce prior to export. Any export, directly or indirectly,
in contravention of the U.S. Export Administration Regulations is prohibited.

Disclaimer

This user’s guide has been validated and reviewed for accuracy. The instructions
and descriptions it contains are accurate for the Toshiba internal modem at the
time of this user’s guide
guides are subject to change without notice. Toshiba assumes no liability for
damages incurred directly or indirectly from errors, omissions or discrepancies
between the modem and the user’s guide.

’s production. However, succeeding products and user’s

Trademarks

Microsoft, MS-DOS and Windows are registered trademarks of Microsoft
Corporation.

Microcom, Microcom Networking Protocol and MNP are registered trademarks
of Microcom, Inc.

Hayes is a registered trademark of Hayes Microcomputer Products Inc.

vi

Contents

V.90 56K
Internal Modem

User’s Guide .................................................................................. i

Contents..................................................................................... vii

Introduction................................................................................ xii

Chapter 1: Setup .......................................................................... 1

Hardware Setup....................................................................... 1

Function check......................................................................... 2

Chapter 2: Using the Internal Modem........................................ 5

Connection procedures .......................................................... 5

Analog or digital?................................................................ 5

Connecting the internal modem........................................ 6

Disconnecting the internal modem................................... 7

Basic operation........................................................................ 7

Connecting to a telephone line........................................... 8

vii

viii

Direct access line ................................................................ 8

Extension line ...................................................................... 8

Receiving a call.................................................................... 9

Terminating a call................................................................ 9

Setting the data flow control............................................ 10

Facsimiles.......................................................................... 11

Chapter 3: AT Commands........................................................ 13

AT command formats........................................................... 13

+++ Escape sequence....................................................... 14

A/ Repeat last command.................................................. 14

A Answer command......................................................... 14

Bn Communication standard setting .............................. 14

Dn Dial................................................................................ 15

En Echo command........................................................... 16

Hn Hook control................................................................ 16

In Request ID information................................................ 17

Ln Monitor speaker volume............................................. 20

Mn Monitor speaker mode.............................................. 20

Nn Modulation handshake............................................... 21

On Return online to data mode ....................................... 21

P Select pulse dialing........................................................ 22

Qn Result code control..................................................... 22

T Select tone dialing.......................................................... 22

Vn DCE response format.................................................. 23

Wn Result Code Option.................................................... 23

Xn Result code selection, call progress monitoring...... 23

Extended result codes ...................................................... 24

Dial tone detect.................................................................. 24

Busy tone detect................................................................ 24

Zn Recall stored profile..................................................... 25

&Cn Data Carrier Detect (DCD) control .......................... 25

&Dn Data Terminal Ready (DTR) control....................... 26

&F Load factory settings .................................................. 26

ix

&Gn V.22bis guard tone control...................................... 26

&Kn Local flow control selection .................................... 27

&Pn Select Pulse Dial Make/Break Ratio ....................... 27

&Tn Self-test commands................................................. 28

&V View active configuration and stored profile............ 28

&W Store current configuration...................................... 30

&Zn=x Store telephone number...................................... 31

\Nn Error control mode selection.................................... 31

Qn Local flow control selection....................................... 32

\Vn Protocol result code................................................... 32

%Cn Data compression control...................................... 33

-V.90=<n>.......................................................................... 33

+MS Command................................................................ 34

+MS= <carrier>, <automode>, <0>, <max_rate>, <0>,

<max_rx_rate> ................................................................. 35

+MS?................................................................................. 35

+MS=?............................................................................... 35

Chapter 4: S-Registers.............................................................. 39

S-Register values.................................................................. 40

S0 Auto answer ring number.......................................... 40

S1 Ring counter................................................................ 40

S2 AT escape character (user-defined)........................... 41

S3 Command line

termination character (user-defined)............................. 41

S4 Response formatting character (user-defined)........ 41

S5 Command line editing character (user defined)....... 41

S6 Wait before dialing...................................................... 42

S7 Connection completion time-out............................... 42

S8 Comma pause time .................................................... 43

S10 Automatic disconnect delay..................................... 43

S11 DTMF dialing speed.................................................. 44

S12 Escape guard time.................................................... 44

S37 Dial line rate............................................................... 44

x

S38 K56flex Dial line rate.................................................. 45

S38 56K Downstream Rate............................................. 45

AT command set result codes ............................................. 46

Chapter 5: MNP and V.42......................................................... 52

Error-correction overview..................................................... 52

MNP error correction........................................................ 52

V.42 error correction......................................................... 53

Operation modes................................................................... 53

Normal mode.................................................................... 53

Reliable mode.................................................................... 53

Commands (\Nn )............................................................. 54

Flow control ........................................................................... 54

Serial port flow control..................................................... 55

XON/XOFF flow control (software).................................. 56

CTS/RTS two-way flow control (hardware)................... 56

Commands (\Qn, &Kn) .................................................... 56

Modem port flow control................................................. 56

Data compression................................................................. 57

Commands (%Cn) ........................................................... 57

Chapter 6: Test Function........................................................... 59

Test description...................................................................... 59

Testing procedure.................................................................. 60

Appendix A: Specifications....................................................... 63

Appendix B: Communication Conditions................................ 66

Glossary..................................................................................... 69

Index........................................................................................... 80

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Function charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Introduction

Congratulations on becoming the owner of a V.90 56K compliant
internal modem offering advanced functions for fax and data
communication. This user’s guide provides detailed information
on features, operation and technical specifications of your internal
modem.

The V.90 56K internal modem provides capability for facsimile
transmissions and standard computer-to-computer data
communications.

The internal modem has a modem port (RJ11) for connecting to an
analog telephone line.

CAUTION: Connect the internal modem ONLY to an analog
line, not to a digital line. For more information, see

“Connection procedures” on page 5.

Due to FCC limitations, speeds of 53 kbps are the maximum
permissible transmission rates during downloads. Actual data
transmission speeds will vary depending on line conditions. Many
users will experience throughput in the range of 32 to 44 kbps
under normal conditions, depending on telephone line quality.

xii

xiii

Some phone lines will not support V.90 56K connections at all,
either because of quality impairments or additional digital-to­analog conversions (i.e., PBX systems). The modem uses the V.34
protocol for “upstream” data transmission, which supports
connection rates of up to 33,600 bits/second.

NOTE: 56K rates can be achieved only when one V.90 56K
modem communicates with a V.90 56K host modem (i.e., a
V.90 56K end-user client modem connects to a V.90 56K
ISP-site modem).

The Toshiba internal modem automatically selects the V.34
protocol if the remote modem lacks V.90 capabilities or if a
combination of network and/or phone line conditions prevent the
V.90 connection. In this case, the maximum connect rate will be
33,600 bits/second.

This section of the user’s guide describes features of the internal
modem.

Features

56K data
communication

Fax capability You can use the internal modem to transmit and

The internal modem uses the V.90 protocol to connect
at data rates of up to 53,000 bits per second (bps) to
other modems employing the V.90 protocol. For
connection to non-V.90 modems, the internal modem
uses the ITU standard V.34 protocol to connect at
rates of up to 33,600 bits per second. The internal
modem also supports all of the earlier, lower-speed
ITU/CCITT modem protocols.

receive facsimiles at rates of up to 14,400 bps. The
internal modem supports Class 1 fax transmission.
Refer to the function charts in this chapter.

xiv

Standard commands The internal modem is compatible with the industry

standard Hayes
settings.

Error control This feature assures accurate data transmission even

over telephone lines subject to noise interference. The
internal modem uses Microcom Networking
Protocol

Data compression Compression can greatly increase data throughput.

The internal modem has MNP5 and V.42bis data
compression protocols.

Serial port access The internal modem frees your computer’s serial port

for connection of a serial mouse, serial printer or other
serial device.

Ring indicator The computer can be powered on automatically when

the modem answers a call. This feature is available
only when the computer is in Resume/Standby mode.
Refer to your computer’s documentation for details on
ring indicator power on.

Standby/Hibernate When the computer is set to Standby or Hibernate, the

modem settings automatically resume when you turn
on the power. Refer to your computer’s
documentation for details on Standby/Hibernate
modes.

®

AT commands and S-Register

®

4 (MNP®4) and V.42 error correction.

xv

Function charts

The chart below lists the internal modem’s supported
communication protocols:

Function Remarks

Data V.90 From 32 Kbps to 56 Kbps

Functions available in all operating systems

V.34 From 2400 bps to 33.6 Kbps

V.32bis 4800, 7200, 9600 bps, 12, 14.4 Kbps

V.32 4800, 9600 bps

V.22bis 1200, 2400 bps

V.22 1200 bps

V.23 75, 600, 1200 bps

V.21 300 bps

BELL212A 1200 bps

BELL103 300 bps

MNP5 Data compression

MNP4 Error control

V.42bis Data compression

V.42 Error control

Fax V.17 7200, 9600 bps, 12, 14.4 Kbps

Note: bps stands for bits per second

Functions available in all operating systems (Continued)

Function Remarks

V.21 ch2 300 bps

EIA-578 Class 1 command set for fax

Note: bps stands for bits per second

User’s guide contents

This user’s guide is composed of six chapters, plus an
Introduction, two appendixes, a glossary, and an index.

❖ The Introduction describes the functions and capabilities of

the internal modem.

xvi

V.29 7200, 9600 bps

V.27ter 2400, 4800 bps

❖ Chapter 1, Setup, describes how to set up and configure the

internal modem and provides information on checking
modem functions.

❖ Chapter 2, Using the Internal Modem, describes basic

operations including connecting the modem and country
selection.

❖ Chapter 3, AT Commands, explains the meanings of the AT

commands that control your internal modem.

❖ Chapter 4, S-Registers, explains the meanings of the registers

that contain the settings for many of the internal modem
functions.

❖ Chapter 5, MNP and V.42, explains error correction, flow

control, and data compression.

xvii

❖ Chapter 6, Test Function, describes how to conduct the

loopback test.

❖ The Appendixes provide technical information.

❖ The Glossary defines telecommunications terminology.

❖ The Index quickly directs you to information contained in the

user’s guide.

Conventions

This user’s guide uses the following formats to describe, identify,
and highlight terms and operating procedures.

Abbreviations

On first appearance, and whenever necessary for clarity,
abbreviations are enclosed in parentheses following their
definition. For example: Read Only Memory (ROM). Acronyms
are also defined in the Glossary.

Keys

The keyboard keys are used in the text to describe many computer
operations. A distinctive typeface identifies the key top symbols as
they appear on the keyboard. For example,
Enter key.

Enter identifies the

Key operation

Some operations require you to simultaneously use two or more
keys. We identify such operations by the key top symbols
separated by a plus sign (+). For example,
hold down
hold down the first two and at the same time press the third.

Ctrl and at the same time press C. If three keys are used,

Ctrl + C means you must

xviii

ATDT Text you are to type in is represented in the

type face you see to the left.

Display

ABC Text generated by the computer that appears on its

display screen is presented in the type face you see to the
left (bold).

Messages

Messages are used in this user’s guide to bring important
information to your attention. Each type of message is identified
as shown below.

CAUTION: Pay attention! A caution informs you that
improper use of equipment or failure to follow instructions
may cause data loss or damage your equipment.

NOTE: Please read. A note is a hint or advice that helps you
make best use of your equipment.

Chapter 1

Hardware Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Function check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Setup

This chapter describes how to set up your hardware and how to
check the internal modem’s functions. It is written primarily for
users who, for some reason, need to set up the modem again.
Some procedures may vary slightly for users who have a
preinstalled modem.

Hardware Setup

Use the MS-DOS® or TSETUP program to set the COM port, I/O
address port, and IRQ level. Refer to your computer’s
documentation.

The default settings are:

Device Configuration All devices

Built-in Modem Com 2 (2F8H/IRQ3)

1

Setup

2

Function check

NOTE: HWSETUP in Windows does not enable changes to
ports.

Function check

Use the Diagnostic function accessible in the Modems Properties
window to check the functions of your internal modem.

To run the diagnostics:

1 Click the Diagnostics tab in the Modems Properties window.

Modem Properties window

2 Select the COM Port for Toshiba Internal V.90 Modem.

(This is the COM port for the Toshiba internal modem.)

Setup

Function check

3 Click More Info . . . .

The system executes an automatic operations test. If the test
does not run or if an error message appears, repeat the setup
procedures.

3

Diagnostics tab More Info... window

Chapter 2

Connection procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Basic operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Using the Internal
Modem

This chapter describes connection procedures and basic
operations.

Connection procedures

This section describes how to connect the internal modem to, and
disconnect it from, a telephone jack.

CAUTION: The modem is designed for use with a standard
analog telephone line. Do not connect the modem to a digital
telephone line. A digital line will damage the modem.

Analog or digital?

❖ If you are not sure which type of line a particular line jack

offers, assume that it is digital and do not connect the internal
modem to it.

❖ If the wall jack is known to be connected to a PBX (Private

Branch Exchange) system, then the line is digital. Do not
connect the modem to it.

5

Using the Internal Modem

6

Connection procedures

❖ If a (working) telephone connected to the wall jack has an

REN (Ringer Equivalency Number) printed on its label, then
it is an analog phone. If the phone is working correctly, then
the wall jack itself is analog.

❖ Telephones in an office environment are commonly

connected to digital phone lines.

❖ Unfortunately, the wall jacks for both analog and digital

phone lines use the familiar RJ11 connector as shown below.
If you are not sure that an RJ11 jack terminates an analog
phone line, do not connect the modem to it.

Connecting the internal modem

CAUTION: In the event of a lightning storm, unplug the
modem cable from the telephone jack.

A standard modular cable is supplied with the internal modem.
Follow the steps below to connect the internal modem to a
telephone jack.

1 Turn the connector so that the small connecting lever faces

down.

2 Squeeze the lever and plug the connector into the computer’s

modem port.

3 Plug the other end of the cable into an RJ11 wall jack.

Connecting the internal modem

Using the Internal Modem

NOTE: When you connect the RJ11 jack, insert it until you
hear a click.

Disconnecting the internal modem

When you need to disconnect the internal modem’s modular cable
for transporting the computer or for some other reason:

1 Pinch the connecting lever on the connector in the telephone

wall jack and pull out the connector.

Squeeze here

Basic operation

7

Disconnecting the cable from the wall jack

2 Disconnect the modular cable from the computer’s modem

port.

Basic operation

After you connect the modular cable to your internal modem and a
telephone line, you are ready to run your communication software.
Refer to your software documentation for instructions on
operating your internal modem.

As examples, this section describes how to execute basic modem
operations by typing AT commands directly into the
communication software program. You must be in terminal mode
to enter the AT commands. Refer to your software documentation
or online help.

Using the Internal Modem

8

Basic operation

Connecting to a telephone line

The AT commands for connecting to a telephone line depend on
whether you are using a direct line or an extension line, such as in
an office building.

Direct access line

❖ To place a call using tone dialing, enter:

ATDT******* and press Enter.

The asterisks * indicate the number you are calling.

❖ To place a call using pulse dialing, enter:

ATDP******* and press Enter.

The asterisks * indicate the number you are calling.

Extension line

If you are calling from an extension line, such as in an office
building, and need to dial nine or another number to gain external
access, follow the steps below.

❖ To place a call using tone dialing, enter:

ATDT 9, ******* and press Enter.

The nine or other number is for line access; the comma (,) is
for a pause (about 2 seconds with the default setting) to give
time for a connection. The asterisks * indicate the number you
are calling.

❖ To place a call using pulse dialing, enter:

ATDP 9, ******* and press Enter.

The nine or other number is for line access; the comma is for a
pause (about 2 seconds with the default setting) to give time
for a connection. The asterisks * indicate the number you are
calling.

You can enter as many commas as you need. The following
example will result in a six-second pause:

ATDT 9, ******* and press Enter.

NOTE: If you are using a PBX connection that does not wait
for a dial tone, add the X0, X1 or X3 to the AT command line.
For example:

Actual usage will vary according to the host system, so
please check with the system manager.

Receiving a call

To set the number of rings before the internal modem
automatically answers the phone, set the S0 register as follows:

ATS0=* and press Enter.

The asterisk * indicates the number of rings.

Using the Internal Modem

Basic operation

ATX3DP 9, ******* and press Enter.

9

See “S-Register values” on page 40 for more details.

Terminating a call

The methods for terminating a call depend on the status of the
connection.

❖ If the internal modem is dialing or has not yet gone online,

you can terminate a call by pressing any key.

❖ If the terminal is online, enter the escape code (+++), then type:

ATH and press Enter.

❖ If the remote party disconnects, the call will be automatically

cut off.

❖ If the power to the computer is cut off, the call is terminated.

Using the Internal Modem

10

Basic operation

Setting the data flow control

Data flow control is used to start and stop data transmission
according to the status of the data buffer (full or empty). The
following describes how to set the data flow control method:

❖ CTS/RTS (hardware control)

❖ XON/XOFF (software)

Also, see “MNP and V.42” on page 52.

CTS/RTS control

This control method is hardware-dependent. To control data flow,
the modem and computer transmit Clear To Send/Request To
Send signals to each other. To set CTS/RTS control, enter the
following AT command:

AT\Q3

XON/XOFF control

This control method is managed by software. The start/stop
signals, that is transfer on/transfer off, are included in the data
stream. To set XON/XOFF control, enter the following AT
command:

AT\Q1

Please use any settings recommended in your communications
software manual.

Facsimiles

Fax communication uses EIA-578 Class 1 commands and
requires fax software. Communication is controlled by the fax
software.

Using the Internal Modem

Basic operation

NOTE: Use only software compatible with EIA-578 Class 1.
Do not use EIA-592 Class 2-compatible software.

11

Chapter 3

AT command formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

AT Commands

In most cases, you will not need to type AT commands manually.
However, there may be some occasions when you will need to do
so.

This chapter describes AT commands for data mode. Fax
commands are taken care of by application software.

AT command formats

The format for entering AT commands is:

ATXn

where X is the AT command, and n is the specific value for some
of the commands. After you type in the command, press

Any command issued is acknowledged with a response in either
text or numeric values known as result codes.

All commands and command-values accepted by the modem are
described in this section; any entry other than those listed results in
an error.

Enter.

If no value is entered for n, then the command defaults to a value
of n=0.

13

AT Commands

14

AT command formats

+++ Escape sequence

The escape sequence allows the modem to exit data mode and
enter online command mode. While in online command mode,

you can communicate directly with your modem using AT
commands. When you finish, you can return to data mode using
the ATO command.

There must be a pause, the length of which is set by Escape Guard
Time (S12), after you enter an escape sequence before any
additional characters can be sent to the modem. This pause
prevents the modem from interpreting the escape sequence as
data.

The value of the escape sequence character may be changed using
register S2.

A/ Repeat last command

This command repeats the last command string entered. Do not
precede this command with an AT prefix nor conclude it by
pressing

Enter.

A Answer command

This command instructs the modem to go off-hook and answer an
incoming call.

Bn Communication standard setting

This command determines the communication standard—either
CCITT or Bell.

NOTE: This command is only useful for matching the
modem to slower modems. It is rarely used today.

Dn Dial

AT Commands

AT command formats

B0 Selects CCITT V.22 mode when the modem is at 1200

bps.

B1 Selects Bell 212A when the modem is at 1200 bps.

B2 Unselects V.23 reverse channel.

B3 Unselects V.23 reverse channel.

B15 Selects V.21 when the modem is at 300 bps.

B16 Selects Bell 103J when the modem is at 300 bps.

15

Result Codes:

:

OK n = 0,1,2,3,15,16

ERROR Otherwise

This command instructs the modem to dial a telephone number.
Enter n (the telephone number and any modifiers) after the ATD
command.

Any digit or symbol (0-9, *, #, A, B, C, D) may be dialed as touch­tone digits. Characters such as spaces, hyphens, and parentheses
do not count. They are ignored by the modem, but you may want
to include them to make the number and modifiers easier to read.

The following may be used as phone number modifiers:

P Pulse dialing.

S=n Dial using the string saved by &Zn command.

T Touch-tone dialing (default).

, Pause during dialing. Pause for time specified in

Register S8 before processing the next character in the
dial string.

W Wait for dial tone. Modem waits for a second dial tone

before processing the dial string.

AT Commands

16

AT command formats

@ Wait for quiet answer. Wait for five seconds of silence

! Hook flash. Causes the modem to go on-hook for 0.5

; Return to command mode. Causes the modem to return

L Redials last number. Should be the first character

$ Bong tone detection

En Echo command

This command controls whether or not the characters entered from
your computer keyboard are displayed on your monitor (echoed)
while the modem is in command mode.

.

E0 Disables echo to the computer.

E1 Enables echo to the computer (default).

after dialing the number. If silence is not detected, the
modem sends a NO ANSWER result code back to the
caller.

seconds and then return to off-hook.

to command mode after dialing a number, without
disconnecting the call.

following ATD; ignored otherwise.

Result Codes:

OK n=0,1

ERROR Otherwise

Hn Hook control

This command instructs the modem to go on-hook to disconnect a
call, or off-hook to make the phone line busy.

H0 Modem goes on-hook (default).

H1 Modem goes off-hook.

Result Codes:

OK n=0,1

ERROR Otherwise

In Request ID information

This command displays product information about the modem.

I0 Returns modem identity string and driver version

number, same as 13.

I1 Calculates ROM checksum and displays it on the DTE.

I2 Performs a ROM check and calculates and verifies the

checksum displaying OK or ERROR.

I3 Returns modem identity string and driver version

number, same as I0

I4 Returns firmware version for data pump.

I5 Returns the code ver, board ID, country ID and

subsystem vendor ID.

I6-8 Returns OK for compatibility.

I9 Returns country ID in English.

I11 The ATI11 result has two pages; you must hit a key to get

the second page. See the following example:

AT Commands

AT command formats

17

ATI11 Description V.90

1 Last Connection V.90

2 Initial transmit Carrier Rate 28800

3 Initial Receive Carrier Rate 49333

4 Final Transmit Carrier Rate 28800

5 Final Receive Carrier rate 49333

6 Protocol Negotiation Result LAPM

18

AT Commands

AT command formats

7 Data Compression Result V42bis

8 Estimated Noise Level 152

9 Receive Signal Power Level (-dBm) 25

10 Transmit Signal Power Level (-dBm) 16

11 Round Trip Delay (msec) 4

Press any key to continue:

12 Near Echo Level (-dBm) NA

13 Far Echo level (-dBm) NA

14 Transmit Frame Count 3

15 Transmit Frame Error Count 0

16 Receive Frame Count 0

17 Receive Frame Error Count 0

18 Retrain by Local Modem 0

19 Retrain by Remote Modem 0

20 Call Termination Cause 0

21 Robbed-Bit Signaling 00

22 Digital Loss (dB) 6

OK

Esc to quit.

The ATI11 command may be issued from online command mode
or after the end of a call. After a call, some of the values are no
longer valid; it’s useful to know which ones.

Each of the line items in the ATI11 results are defined as follows:

1 V.90, V.34, or V.32 depending on the type of connection

negotiated.

2 Initial upstream rate.

3 Initial downstream rate.

4 Current or final upstream rate.

5 Current or final downstream rate.

AT Commands

AT command formats

6 LAPM or MNP or None, depending on V.42 negotiation.

7 V42bis or MNP or None, depending on V.42 negotiation.

8 Mean-square error of received downstream signal. This is a

dimensionless decimal number, only valid during a call.
Higher numbers are worse. There’s no absolute threshold of
good reception; it depends on the downstream data rate. The
number varies during a call, so it can be useful to sample it a
few times.

9 The received signal power, although labeled -dBm, is only a

relative measure for comparing calls to/from different
locations. Only valid during a call.

10 Upstream transmit signal power.

11 Round-trip delay in millliseconds.

12 Echo levels are valid for V.34 only.

13 Echo levels are valid for V.34 only.

19

14 Number of LAPM frames sent upstream during this call.

Count wraps around at 65535.

15 Number of REJ frames received at the analog client modem.

16 Number of LAPM frames received by client during this call.

Count wraps around at 65535.

17 Number of frames received in error by the client.

18 Number of retrains or rate renegotiations requested by this

modem.

19 Number of retrains or rate renegotiations requested by remote

modem.

20 Reason for call ending, only valid after call ends:

0 = Local modem command: ATH, DTR drop

1 = Remote modem: cleardown, loss of signal

AT Commands

20

AT command formats

2 = No answer, busy, etc.

3 = Training failure V.90, 56K or V.34

4 = Protocol failure if required by \N4, for example.

21 For PCM connection only, a hexidecimal 6-bit pattern of T1

frames with robbed-bit signaling.

22 For PCM connection only, the downstream digital loss.

Result Codes:

As described n=0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11

ERROR Otherwise

Ln Monitor speaker volume

This command sets speaker volume to low, medium, or high.

L0 Low volume

L1 Low volume (Same as L0)

L2 Medium volume (default)

L3 High volume

Result Codes:

OK n=0,1,2,3

ERROR Otherwise

Mn Monitor speaker mode

This command turns the speaker on or off.

M0 The speaker is off.

M1 The speaker is on until the modem detects the carrier

signal (default).

M2 The speaker is always on when modem is off-hook.

Result Codes:

OK n=0,1,2

ERROR Otherwise

Nn Modulation handshake

This command controls whether or not the local modem performs
a negotiated handshake at connection time with the remote
modem when the communication speed of the two modems is
different.

N0 When originating or answering, this is for handshake

only at the communication standard specified by S37 and
the ATB command.

N1 When originating or answering, begin the handshake at

the communication standard specified by S37 and the
ATB command (default).

During handshake, a lower transmission speed may be
selected.

AT Commands

AT command formats

21

Result Codes:

OK n=0,1

ERROR Otherwise

On Return online to data mode

O0 Instructs the modem to exit online command mode and return

to data mode (see AT escape sequence, +++).

O1 This command issues a retrain before returning to online data

mode.

AT Commands

22

AT command formats

O3 This command issues a rate renegotiation before returning to

online data mode.

Result Codes:

OK n=0,1,3

ERROR Otherwise

P Select pulse dialing

This command configures the modem for pulse (non-touch-tone)
dialing. Dialed digits are pulsed until a T command or dial
modifier is received. Tone dial is the default setting.

Qn Result code control

Result codes are informational messages sent from the modem
and displayed on your monitor. Basic result codes are OK,
CONNECT, RING, NO CARRIER, and ERROR. The ATQ
command allows the user to turn result codes on or off.

Q0 Enables modem to send result codes to the computer

(default).

Q1 Disables modem from sending result codes to the computer.

Result Codes:

OK n=0,1

ERROR Otherwise

T Select tone dialing

This command instructs the modem to send DTMF tones while
dialing. Dialed digits are tone dialed until a P command or dial
modifier is received. This is the default setting.

Vn DCE response format

This command controls whether result codes (including call
progress and negotiation progress messages) are displayed as
words or their numeric equivalents.

V0 Displays result codes as digits.

V1 Displays result codes as text (default).

Result Codes:

OK n=0,1

ERROR Otherwise

Wn Result Code Option

W0 CONNECT result code reports DTE speed. Disable

protocol result codes.

W1 CONNECT result code reports DTE speed. Enable

protocol result codes.

W2 CONNECT result code reports DTE speed. Enable

protocol result codes (default).

AT Commands

AT command formats

23

Result Codes:

OK n=0,1,2

ERROR Otherwise

Xn Result code selection, call progress monitoring

This command sets detection options for dial tones and busy
signals, which is its primary function. However, it also enables or
disables extended result codes.

24

AT Commands

AT command formats

Command

X0 Disable Disable Disable

X1 Enable Disable Disable

X2 Enable Enable Disable

X3 Enable Disable Enable

X4 (default) Enable Enable Enable

X5 Enable Enable Enable

X6 Enable Enable Enable

X7 Disable Enable Enable

Extended result codes

Disabled: Displays only the basic result codes: OK,

Enabled: Displays basic result codes, along with the connect

Extended

Result code

CONNECT, RING, NO CARRIER, and ERROR.

message and the modem’s data rate, and an
indication of the modem’s error correction and data
compression operation

Dial tone

Detect

Busy signal

Detect

Dial tone detect

Disabled: The modem dials a call regardless of whether it

Enabled: The modem dials only upon detection of a dial tone,

Busy tone detect

Disabled: The modem ignores any busy tones it receives.

detects a dial tone. The period of time the modem
waits before dialing is specified in register S6.

and disconnects the call if the dial tone is not
detected within 10 seconds.

AT command formats

Enabled: The modem monitors for busy tones.

Result Codes:

OK n=0,1,2,3,4,5,6,7

ERROR Otherwise

Zn Recall stored profile

The modem performs a soft reset and restores (recalls) the
configuration profile according to the parameter supplied. If no
parameter is specified, zero is assumed. Either Z0 or Z1 restores
the profile.

Result Codes:

OK n=0,1

ERROR Otherwise

&Cn Data Carrier Detect (DCD) control

AT Commands

25

Data Carrier Detect is a signal from the modem to the computer
indicating that a carrier signal is being received from a remote
modem. DCD normally turns off when the modem no longer
detects the carrier signal.

&C0 The state of the carrier from the remote modem is

ignored. DCD circuit is always on.

&C1 DCD turns on when the remote modem’s carrier

signal is detected, and off when the carrier signal is not
detected (default).

Result Codes:

OK n=0,1

ERROR Otherwise

AT Commands

26

AT command formats

&Dn Data Terminal Ready (DTR) control

This command interprets how the modem responds to the state of
the DTR signal and changes to the DTR signal.

&D0 Ignore. The modem ignores the true status of DTR

and treats it as always on. This should only be used if
your communication software does not provide DTR
to the modem.

&D1 If the DTR signal is not detected while in online data

mode, the modem enters command mode, issues an
OK result code, and remains connected.

&D2 If the DTR signal is not detected while in online data

mode, the modem disconnects (default).

&D3 Reset the modem on the on-to-off DTR transition.

Result Codes:

OK n=0,1,2,3

ERROR Otherwise

&F Load factory settings

This command loads the configuration stored and programmed at
the factory. This operation replaces all of the command options
and the S-Register settings in the active configuration with factory
values.

&F Recall factory setting as active configuration.

&Gn V.22bis guard tone control

This command determines which guard tone, if any, to transmit
while transmitting in the high band (answer mode). This

command is only used in V.22 and V.22bis mode. This option is
not used from North America and is for international use only.

&G0 Guard tone disabled (default).

&G1 Sets guard tone to 550 Hz.

&G2 Sets guard tone to 1800 Hz.

Result Codes:

OK n=0,1,2

ERROR Otherwise

&Kn Local flow control selection

&K0 Disables flow control.

&K3 Enables RTS/CTS flow control (default).

&K4 Enables XON/XOFF flow control.

AT Commands

AT command formats

27

Result Codes:

OK n=0,3,4

ERROR Otherwise

&Pn Select Pulse Dial Make/Break Ratio

&P0 Selects 39% - 61% make/break ratio at 10 pulses

per second.

&P1 Selects 33% - 67% make/break ratio at 10 pulses

per second.

&P2 Selects 33% - 67% make/break ratio at 20 pulses

per second.

AT Commands

28

AT command formats

Result Codes:

OK n=0 to 2

ERROR Otherwise

&Tn Self-test commands

These tests can help to isolate problems if you experience periodic
data loss or random errors.

&T0 Abort. Stops any test in progress.

&T1 Local analog loop. This test verifies modem operation, as

well as the connection between the modem and
computer. Any data entered at the local DTE is
modulated, then demodulated, and returned to the local
DTE. To work properly, the modem must be offline.

Result Codes:

OK n=0

CONNECT n=1

ERROR Otherwise

&V View active configuration and stored profile

This command is used to display the active profiles on your
computer’s monitor.

&V View active file

For example:

Option Selection AT Command

Comm Standard Bell B

Command Char Echo Enable E

AT Commands

AT command formats

Option Selection AT Command

Speaker Volume Medium L

Speaker Control OnUntilCarr M

Result Codes Enable Q

Dialer Type Tone T/P

Result Code Form Text V

Extend Result Code Enable X

Dial Tone Detect Enable X

Busy Tone Detect Enable X

LSD Action Standard RS-

232C

DTR Action Ignore &D

Press any key to continue; Esc to quit.

Option Selection AT Command

V.22b Guard Tone Disable &G

Flow Control Hardware &K

Error Control Mode V.42, MNP, Buffer \N

Data Compression Enable %C

Auto AnswerRing# 0 S0

AT Escape Char 43 S2

CarriageRtn Char 13 S3

Linefeed Char 10 S4

Backspace Char 8 S5

Blind Dial Pause 2 sec. S6

NoAnswer Timeout 50 sec. S7

“,” Pause Time 2 sec. S8

29

&C

Press any key to continue;

Esc to quit.

30

AT Commands

AT command formats

Option Selection AT Command

No Carrier Disc 2000 msec. S10

DTMF Dial Speed 95 msec. S11

Escape GuardTime 1000 msec. S12

Data Calling Tone Disabled S35

Line Rate 33600 S37

Press any key to continue; Esc to quit.

Stored phone numbers

&Z0=

&Z1=

&Z2=

&Z3=

OK

&W Store current configuration

Saves the current (active) configuration (profile), including S­Registers.

The current configuration comprises a list of storable parameters
illustrated in the &V command. These settings are restored to the
active configuration upon receiving a Zn command or at power­up. Refer to the &V command.

&W Stores the current configuration.

Result Codes:

OK n = 0.

ERROR Otherwise

&Zn=x Store telephone number

This command is used to store up to four dialing strings in the
modem’s nonvolatile memory for later dialing. The format for the
command is &Zn=“stored number” where n is the location 0-3 to
which the number should be written. The dial string may contain
up to 40 characters. The ATDS=n command dials using the string
stored in location n.

Result codes:

OK n = 0, 1, 2, 3

ERROR Otherwise

\Nn Error control mode selection

This command determines the type of error control used by the
modem when sending or receiving data.

AT Commands

AT command formats

31

\N0 Buffer mode. No error control. (Also known as Normal

Mode.)

\N1 Same as \N0.

\N2 MNP or disconnect mode. The modem attempts to

connect using MNP2-4 error control procedures. If this
fails, the modem disconnects.

This is also known as MNP-reliable mode.

\N3 V.42, MNP, or buffer (default).

The modem attempts to connect in V.42 error control
mode. If this fails, the modem attempts to connect in
MNP mode. If this fails, the modem connects in buffer
mode and continues operation. This is also known as
V.42/MNP auto-reliable mode.

\N4 V.42 or disconnect. The modem attempts to connect in

V.42 error control mode. If this fails, the call will be
disconnected.

AT Commands

32

AT command formats

\N5 V.42. MNP or Buffer (same as \N3).

\N7 V.42. MNP or Buffer (same as \N3).

Result Codes:

OK n = 0, 1, 2, 3,4,5,7

ERROR Otherwise

Qn Local flow control selection

\Q0 Disable flow control.

\Q1 XON/XOFF software flow control.

\Q3 RTS/CTS to DTE (default).

Result Codes:

OK n = 0, 1, 3

ERROR Otherwise

\Vn Protocol result code

\V0 Disable protocol result code appended to DCE speed.

\V1 Enable protocol result code appended to DCE speed

(default).

Result Codes:

OK n = 0, 1

ERROR Otherwise

%Cn Data compression control

This command determines the operation of V.42bis and MNP
class 5 data compression. Online changes do not take effect until a
disconnect occurs first.

%C0 V.42bis/MNP 5 disabled. No data compression.

%C1 V.42bis/MNP 5 enabled. Data compression enabled (default).

Result Codes:

OK n = 0, 1

ERROR Otherwise

-V.90=<n>

This command enables/disables V.90 and changes the
downstream rate.

AT Commands

AT command formats

33

-V90=0 Disables V.90

-V90=1 Enables V.90 Auto rate (default value)

-V90=X Controls the downstream rate

-V90? Shows the current value

-V90=? Shows the range [0-21]

Possible values of n:

“AT-V90=X” Downstream Rate

0 V.90 disabled

1 Auto rate (Default)

2 28000 bps

3 29333 bps

4 30666 bps

34

AT Commands

AT command formats

5 32000 bps

6 33333 bps

7 34666 bps

8 36000 bps

9 37333 bps

10 38666 bps

11 40000 bps

12 41333 bps

13 42666 bps

14 44000 bps

15 45333 bps

16 46666 bps

17 48000 bps

18 49333 bps

19 50666 bps

20 52000 bps

21 53333 bps

+MS Command

This command can be used to set protocol and connection speed
parameters for the modem. Instead of having to change multiple S
registers, this single command produces the same effect. The
command can also be used to provide information concerning the
current modem protocol settings and maximum connection speed
settings. In addition, it can be used to indicate all the possible
settings available for the modem.

AT Commands

AT command formats

+MS= <carrier>, <automode>, <0>, <max_rate>, <0>, <max_rx_rate>

This command is used to set the various parameters described
below:

<carrier> A modem connect protocol string, such as

V.90 or 56K

<automode> 0 Disables automatic modulation negotiation

1 Enables automatic modulation negotiation

<max_rate> The maximum transmit rate. If set to 0, then

the max rate will be determined by the
modulation means selected in the <carrier>
and <automode> settings.

<max_rx_rate> Sets the fastest receive carrier speed. If set to

0, then max rate will be determined by the
modulation means selected in the <carrier>
and <automode> settings.

35

+MS?

+MS=?

Example: +MS=V90C,1,0,0,0,0

This sets the modulation to be V.90 and the speed negotiations
to use automode. This is the modem default.

Example: +MS=V90C,1,0,0,0,45333

This will limit the maximum receive connect carrier speed to
45,333 bps in V.90 mode.

This command returns the current +MS sub parameter settings.

This command returns a listing of all supported values for each
sub parameter. For the current modem driver, the response is the
following:

36

AT Commands

AT command formats

+MS:(V21,V22,V22B,V23,V32,V32B,V34,V90C,56K),(0,1),
(0),(0,300-33600),(0),(0,300-56000)

The valid values for carrier are:

Va l u e M e a n i n g

V90C or V90 V90

K56 K56flex

V34 V34

V32 V32

V32B V32bis

V22 V22

V22B V22bis

V23 V23

V21 V21

The valid values for max_rate for the different carriers are:

Va l u e M e a n i n g

V90, K56, V34 2400-33600 in steps of 2400

V32bis 4800-19200 in steps of 2400

V32 4800-14400 in steps of 2400

V22bis 2400

V22 2200

V23 1200

V21 300

The valid values for max_rx_rate for the different carriers are:

Va l u e M e a n i n g

V90 28000-56000 in steps of 1333

K56 32000-56000 in steps of 2000

V34 2400-33600 n steps of 2400

AT Commands

AT command formats

V32bis 4800-19200 in steps of 2400

V32 4800-14400

V22bis 2400

V22 2200

V23 1200

V21 300

37

Chapter 4

S-Register values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

AT command set result codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

S-Registers

S-Registers contain the settings that determine how several
functions of the internal modem operate, such as choosing how
many times to let the telephone ring before the modem answers
and how long to wait before it hangs up if a connection fails. You
can also customize certain AT commands, such as the escape
sequence and command line termination.

The contents of the registers are changed automatically when you
modify corresponding settings in your communication software. If
you choose, however, you can display and edit the contents of the
registers manually when the modem is in command mode. If the
value is outside the acceptable range, an error is generated.

This chapter describes the settings for each S-Register.

39

S-Registers

40

S-Register values

S-Register values

❖ The format for displaying the value of an S-Register is:

ATSn?

where n is the register number. After you type in the register
press

Enter.

❖ The format for modifying the value of an S-Register is:

ATSn=r

where n is the register number, and r is the new register value.
After you type in the register number and its new value press

Enter.

S0 Auto answer ring number

This register determines the number of rings the modem will
count before automatically answering a call. Enter
do not want the modem to automatically answer at all. When
disabled, the modem can only answer with an ATA command.

0 (zero) if you

Range: 0-255

Default: 0

Units: rings

S1 Ring counter

This register is read-only. The value of S1 is incremented with
each ring. If no ring occurs over a six-second interval, the register
is cleared.

Range: 0-225

Default: 0

Units: rings

S-Registers

S-Register values

S2 AT escape character (user-defined)

This register determines the ASCII value used for an escape
sequence. The default is the + character. The escape sequence
allows the modem to exit data mode and enter command mode
when online. Values greater than 127 disable the escape sequence.

Range: 0-255

Default: 43

Units: ASCII

S3 Command line termination character (user-defined)

This register determines the ASCII values as the carriage return
character. This character is used to end command lines and result
codes.

Range: 0-127, ASCII decimal

Default: 13 (carriage return)

Units: ASCII

41

S4 Response formatting character (user-defined)

This register determines the ASCII value used as the line feed
character. The modem uses a line feed character in command
mode when it responds to the computer.

Range: 0-127, ASCII decimal

Default: 10 (line feed)

Units: ASCII

S5 Command line editing character (user defined)

This register sets the character recognized as a backspace and
pertains to asynchronous transmission only. The modem will not

S-Registers

42

S-Register values

recognize the backspace character if it is set to an ASCII value
greater than 32. This character can be used to edit a command line.
When the echo command is enabled, the modem echoes back to
the local DTE the backspace character, an ASCII space character,
and a second backspace character. This means a total of three
characters are transmitted each time the modem processes the
backspace character.

Range: 0-127, ASCII decimal

Default: 8 (backspace)

Units: ASCII

S6 Wait before dialing

This register sets the length of time, in seconds, that the modem
must wait (pause) after going off-hook before dialing the first digit
of the telephone number. The modem always pauses for a
minimum of two seconds, even if the value of S6 is less than two
seconds. The wait for dial tone call progress feature (W dial
modifier in the dial string) will override the value in register S6.

Range: 2-65

Default: 2

Units: seconds

S7 Connection completion time-out

This register sets the time, in seconds, that the modem must wait
before hanging up because the carrier is not detected. The timer is
started when the modem finishes dialing (originate), or goes off­hook (answer). In originate mode, the timer is reset upon detection
of an answer tone if allowed by county restriction. The timer also
specifies the wait for silence time for the @ dial modifier in
seconds. S7 is not associated with the W dial modifier.

Range: 1-255

Default: 50

Units: seconds

S8 Comma pause time

This register sets the time, in seconds, that the modem must pause
when it encounters a comma (,) in the dial command string.

Range: 0-65

Default: 2

Units: seconds

S10 Automatic disconnect delay

This register sets the length of time, in tenths of a second, that the
modem waits before hanging up after a loss of carrier. This allows
for temporary carrier loss without causing the local modem to
disconnect.

S-Registers

S-Register values

43

The actual interval the modem waits before disconnection is the
value in register S10.

Range: 1-254

Default: 20

Units: .1 seconds

S-Registers

44

S-Register values

S11 DTMF dialing speed

This register determines the dialing speed.

Range: 50-150

Default: 95

Units: .001 seconds

S12 Escape guard time

This register sets the value (in 20 ms increments) for the required
pause after the escape sequence (default 1 second).

Range: 0-255

Default: 50

Units: .02 seconds

S37 Dial line rate

S37 = 0 (default) maximum modem speed

S37 = 1 reserved

S37 = 2 1200/75 bps

S37 = 3 300 bps

S37 = 4 reserved

S37 = 5 1200 bps

S37 = 6 2400 bps

S37 = 7 4800 bps

S37 = 8 7200 bps

S37 = 9 9600 bps

S37 = 10 12000 bps

S37 = 11 14400 bps

S37 = 12 16800 bps

S37 = 13 19200 bps

S37 = 14 21600 bps

S37 = 15 24000 bps

S37 = 16 26400 bps

S37 = 17 28800 bps

S37 = 18 31200 bps

S37 = 19 33600 bps

S38 K56flex Dial line rate

S38 enables and disables K56flex mode and sets the maximum
K56flex downstream speed that the modem attempts to connect.

S38=0 56K disabled (default)

S38=1 56K enabled: automatic speed selection of

maximum modem speed

S-Registers

S-Register values

45

NOTE: Not all modems support K56flex. If this command
returns an ERROR, then K56flex is not supported.

S38 56K Downstream Rate

To force a particular 56K downstream rate, use S-register S38.
S38=0 disables 56K, and may allow a more reliable V.34
connection. S38=1 (default) allows the modem to select the
downstream rate automatically. Other values of S38 force the
downstream rate, with fallback to V.34 if unsuccessful at the
configured rate:

S38=0 Disable 56K

S38=1 Automatic rate selection (default)

S38=2 32 kbps

S-Registers

46

AT command set result codes

S38=3 34 kbps

S38=4 36 kbps

S38=5 38 kbps

S38=6 40 kbps

S38=7 42 kbps

S38=8 44 kbps

S38=9 46 kbps

S38=10 48 kbps

S38=11 50 kbps

S38=12 52 kbps

S38=13 54 kbps

S38=14 56 kbps

AT command set result codes

The following table shows the result codes.

Command Set Result Codes Table

Result Code Numeric Description

OK 0 Command executed

CONNECT 1 Modem connected to line

RING 2 A ring signal has been detected

NO CARRIER 3 Modem lost carrier signal, or does

not detect carrier signal, or does
not detect answer tone

* EC appears only when the Extended Result Codes configuration option is enabled. EC is replaced
by one of the following symbols, depending upon the error control method used:

V.42bis - V.42 error control and V.42bis data compression

V.42 - V.42 error control only

MNP 5 - MNP class 4 error control and MNP class 5 data compression

MNP 4 - MNP class 4 error control only

NoEC - No error control protocol

S-Registers

AT command set result codes

Command Set Result Codes Table (Continued)

Result Code Numeric Description

ERROR 4 Invalid command

CONNECT 1200 EC

NO DIAL TONE 6 No dial tone detected

BUSY 7 Busy signal detected

CONNECT 2400 EC

CONNECT 4800 EC

CONNECT 9600 EC

CONNECT 14400 EC

CONNECT 19200 EC

CONNECT 7200 EC

CONNECT 12000 EC

CONNECT 16800 EC

CONNECT 300 EC

CONNECT 21600 EC

CONNECT 24000 EC

CONNECT 26400 EC

CONNECT 28800 EC

CONNECT 31200 EC

CONNECT 33600 EC

CONNECT 38400 EC

* EC appears only when the Extended Result Codes configuration option is enabled. EC is replaced
by one of the following symbols, depending upon the error control method used:

V.42bis - V.42 error control and V.42bis data compression

V.42 - V.42 error control only

MNP 5 - MNP class 4 error control and MNP class 5 data compression

MNP 4 - MNP class 4 error control only

NoEC - No error control protocol

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

5 Connection at 1200 bps

10 Connection at 2400 bps

11 Connection at 4800 bps

12 Connection at 9600 bps

13 Connection at 14400 bps

14 Connection at 19200 bps

24 Connection at 7200 bps

25 Connection at 12000 bps

86 Connection at 16800 bps

40 Connection at 300 bps

55 Connection at 21600 bps

56 Connection at 24000 bps

57 Connection at 26400 bps

58 Connection at 28800 bps

59 Connection at 31200 bps

60 Connection at 33600 bps

28 Connection at 38400 bps (DTE

rate)

47

S-Registers

48

CONNECT 57600 EC

CONNECT 115200 EC* 87 Connection at 115200 bps (DTE

CONNECT 32000 EC

CONNECT 34000 EC

CONNECT 36000 EC

CONNECT 38000 EC

CONNECT 40000 EC

CONNECT 42000 EC

CONNECT 44000 EC

CONNECT 46000 EC

CONNECT 48000 EC

CONNECT 50000 EC

* EC appears only when the Extended Result Codes configuration option is enabled. EC is replaced
by one of the following symbols, depending upon the error control method used:

AT command set result codes

Command Set Result Codes Table (Continued)

Result Code Numeric Description

*

*

*

*

*

*

*

*

*

*

*

V.42bis - V.42 error control and V.42bis data compression

V.42 - V.42 error control only

MNP 5 - MNP class 4 error control and MNP class 5 data compression

MNP 4 - MNP class 4 error control only

NoEC - No error control protocol

18 Connection at 57600 bps (DTE

rate)

rate)

70 Connection at 32000 bps (56K

mode) or V.90

71 Connection at 34000 bps (56K

mode)

72 Connection at 36000 bps (56K

mode) or V.90

73 Connection at 38000 bps (56K

mode)

74 Connection at 40000 bps (56K

mode) or V.90

75 Connection at 42000 bps (56K

mode)

76 Connection at 44000 bps (56K

mode) or V.90

77 Connection at 46000 bps (56K

mode)

78 Connection at 48000 bps (56K

mode) or V.90

79 Connection at 50000 bps (56K

mode)

S-Registers

AT command set result codes

Command Set Result Codes Table (Continued)

Result Code Numeric Description

CONNECT 52000 EC

CONNECT 54000 EC

CONNECT 56000 EC

CONNECT 28000 EC* 100 Connection at 28000 bps (V.90

CONNECT 29333 EC* 101 Connection at 29333 bps (V.90

CONNECT 30666 EC* 102 Connection at 30666 bps (V.90

CONNECT 33333 EC* 103 Connection at 33333 bps (V.90

CONNECT 34666 EC* 104 Connection at 34666 bps (V.90

CONNECT 37333 EC* 105 Connection at 37333 bps (V.90

CONNECT 38666 EC* 106 Connection at 38666 bps (V.90

CONNECT 41333 EC* 107 Connection at 41333 bps (V.90

CONNECT 42666 EC* 108 Connection at 42666 bps (V.90

* EC appears only when the Extended Result Codes configuration option is enabled. EC is replaced
by one of the following symbols, depending upon the error control method used:

V.42bis - V.42 error control and V.42bis data compression

V.42 - V.42 error control only

MNP 5 - MNP class 4 error control and MNP class 5 data compression

MNP 4 - MNP class 4 error control only

NoEC - No error control protocol

*

*

*

80 Connection at 52000 bps (56K

mode) or V.90

81 Connection at 54000 bps (56K

mode)

82 Connection at 56000 bps (56Kflex

mode)

mode)

mode)

mode)

mode)

mode)

mode)

mode)

mode)

mode)

49

S-Registers

50

CONNECT 45333 EC* 109 Connection at 45333 bps (V.90

CONNECT 46666 EC* 110 Connection at 46666 bps (V.90

CONNECT 49333 EC* 111 Connection at 49333 bps (V.90

CONNECT 50666 EC* 112 Connection at 50666 bps (V.90

CONNECT 53333 EC* 113 Connection at 53333 bps (V.90

CONNECT 54666 EC* 114 Connection at 54666 bps (V.90

* EC appears only when the Extended Result Codes configuration option is enabled. EC is replaced
by one of the following symbols, depending upon the error control method used:

AT command set result codes

Command Set Result Codes Table (Continued)

Result Code Numeric Description

mode)

mode)

mode)

mode)

mode)

mode)

V.42bis - V.42 error control and V.42bis data compression

V.42 - V.42 error control only

MNP 5 - MNP class 4 error control and MNP class 5 data compression

MNP 4 - MNP class 4 error control only

NoEC - No error control protocol

Chapter 5

Error-correction overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Flow control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Data compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

MNP and V.42

The internal modem has built-in protocols MNP® (Microcom
Networking Protocol) Class 4 and V.42 for error correction and
MNP class 5 and V.42bis for data compression.

Error-correction overview

Telephone line noise, or electrical interference, can cause errors in
data communication. Noise is especially a problem at high speeds
of 14,400 bps or greater.

The MNP and V.42 protocols were developed to ensure reliable
data communications despite the high probability of error
generation from line noise.

MNP error correction

MNP was developed by Microcom. MNP class 4 enables data
correction of full-duplex communications and also provides
asynchronous/synchronous conversion and data packet-size
negotiation to increase throughput.

52

The protocol of both modems must be the same. Therefore, if the
remote modem supports only class 3 or below, the protocol for the
remote modem will be used. If the remote modem does not use
MNP, the communication will be made at the speed of the remote
modem.

V.42 error correction

The V.42 (ITU-T-Rec V.42) protocol is recommended by the ITU
(International Telecommunications Union). V.42 specifies two
kinds of protocols, LAP-M (Link Access Procedure for Modem)
and MNP classes 2, 3, and 4. This protocol first tries to establish a
link to the remote modem with LAP-M. If it is unsuccessful, it
tries to connect with MNP. Although this modem uses class 4
correction, it can connect in class 5 to remote modems that support
class 5.

Operation modes

MNP and V.42

Operation modes

53

The operation mode depends on whether an error-correction
protocol is being used.

Normal mode

Errors are not corrected, even if communication speed is different
between a personal computer and modem, or between modems,
the buffers in the modem and the flow control function permit
communication without changing communication speed.

Reliable mode

This mode is used with MNP or V.42 protocols to ensure error­free communication.

MNP and V.42

54

Flow control

Commands (\ Nn )

The following N modulation handshake commands are used to set
the communication mode:

\N0, \N1 Remote modem unable to use MNP or V.42

\N2 Remote modem uses MNP

\N3 Uncertain if remote modem can use MNP or

\N4 Remote modem uses V.42

\N5, \N7 Same as \N3

For details, refer to “AT Commands” on page 13.

Flow control

V. 4 2

In both normal mode and reliable mode, the buffers in the modem
and its flow control function permit communication even if the
speed is different between a personal computer and modem (serial
port) or between modems (modem port).

If there is a speed difference between the serial port and modem
port, the buffers in the modem will become full periodically.
Therefore, the communication activity is controlled so that data
transmission or reception is temporarily halted before the data
exceeds buffer capacity, and transmission is resumed when the
receiving buffers have room. This is the flow control function.

MNP and V.42

Flow control

The modem card has two kinds of flow control:

❖ Serial port flow control

❖ Modem port flow control (only in reliable mode)

55

Computer

DTE
Transmit

Receive

Flow control

Serial port flow control

Serial port data flow is controlled by the modem in its
communication with a personal computer.

If the serial port speed is higher than the modem port speed, this
control function sends a transmission halt request to the personal
computer before the buffers in the modem are about to become
full. When the buffers have room to receive data again, the
transmission halt request is canceled and data transmission from
the personal computer is resumed.

Modem

Buffer

Buffer

Serial port
flow control

DCE
Phone line

Modem port
flow control

Phone
Circuit

The internal modem provides three kinds of serial port flow
control: one determined by software and two determined by
hardware.

MNP and V.42

56

Flow control

XON/XOFF flow control (software)

Flow control is performed by sending XON and XOFF control
codes in the data stream. The XOFF code makes a transmission
halt request. The XON code makes a transmission restart request.

Since these two codes, XON and XOFF, are used as flow control
characters, binary data that includes these two codes cannot be
transmitted or received.

CTS/RTS two-way flow control (hardware)

Flow control is performed by turning on and off the control lines
CTS (clear to send) and RTS (request to send) between the
modem and the computer. A transmission halt or restart request is
made from the modem to the computer using the CTS signal.

A transmission halt or restart request is made from the personal
computer to the modem using the RTS signal.

Commands (\Qn, &Kn)

Select flow control between the modem and computer (serial port)
as follows:

❖ When CTS/RTS flow control is supported by the

communication software

\Q3, &K3 Communication in reliable mode or normal mode

❖ When XON/OFF flow control is only supported by the

communication software

\Q1, &K4 Communication in reliable mode or normal mode

For details, refer to “AT Commands” on page 13.

Modem port flow control

Modem port flow control refers to flow control between the
modems of the local station and remote station.

If data transmission from the modem under serial port flow control
is interrupted because the computer cannot catch up with it,
modem port flow control is applied to the remote modem so that
transmitted data will not exceed buffer capacity. This flow control
functions in normal mode only.

Data compression

Protocols MNP class 5 and V.42bis are included in the modem to
compress data received from the computer. The receiving modem
decompresses the received data and sends it to its own computer.
This data compression function increases actual transmission
speed up to twofold in communications using MNP5 or up to
three or fourfold in communications using V.42bis. The
compression ratio varies depending on the data. Actual speed will
not always be raised close to the maximum compression ratio.

Commands (%Cn)

MNP and V.42

Data compression

57

Select whether or not to compress data in communications by
MNP class 5 or V.42bis as follows:

%C1 Enables data compression

For details, refer to “AT Commands” on page 13.

Chapter 6

Test description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Testing procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Test Function

Normally, data communications are executed by connecting your
computer and modem to those of a remote station with a
communication line. If any errors or malfunctions are
encountered, it is necessary to check whether the cause is in the
local station, the remote station or the communication line.

Test description

This internal modem has a local/analog/loopback test function that
identifies the cause of a malfunction. You can use the test to check
errors in data communications or to check operation following
modem connection.

When conducting a test, use the &T command to select test mode
and control. For details on the &T command, refer to “&Tn Self-

test commands” on page 28.

In this test, data is transmitted from the computer, is looped back
(analog/loopback) within the modem from the transmitter to the
receiver, then sent back to the computer. The test enables you to
check whether the computer and modem are working properly.

59

60

Test Function

Testing procedure

Computer

Local/analog/loopback test

Testing procedure

To conduct the loopback test:

1 Enter the following AT commands to set the modem to

normal mode:

AT&F\N0

Receive OK

Transmission

Reception

Modem

Transmitter

Receiver

Test Function

Testing procedure

2 Enter the following AT commands to select the local/analog/

loopback test:

AT&T1

You are now in the online state.

3 Enter characters from the keyboard as desired.

The characters you enter should be displayed on the screen.

4 Enter the escape code as follows to return to the command

state from the online state.

+++

Receive OK.

5 Enter the following AT commands to terminate the test:

AT&T0

Receive OK.

61

Appendix A

Specifications

This appendix summarizes the Toshiba internal modem’s
technical specifications.

Network control unit (NCU)

Type of NC U AA

Type of line General telephone line

Type of dialing Pulse

To ne

Control command AT commands

EIA-578 commands

Monitor function Computer’s speaker

63

Specifications

64

Communication specifications

Communication
system

Communication
protocol

Communication
speed

Data: Full duplex

Fax: Half duplex

Data ITU-T-Rec

V.21 / V.22 / V.22bis / V.32 /
V.32bis / V.34 / 56K / V.90

Bell

103/212A

Fax ITU-T-Rec

V. 1 7 / V. 29 / V. 2 7 ter

(Former CCITT) /V.21 ch2

Data 300 / 1200 / 2400 / 4800 /7200 /

9600 / 12000 / 14400 /16800 /
19200 / 21600 /24000 / 26400 /
28800 /29333/30666/33333/
34666/37333/38666/41333/
42666/45333/46666/49333/
50666/53333/54666 bps

Transmitting
level

Fax 2400 / 4800 / 7200 / 9600 /

12000 / 14400 bps

-10 dBm

Appendix B

Communication
Conditions

Communication parameters

Select communication parameters from the table below.

Start

Data length

(bit)

(bit)

1 8 None 1 or more

17 0 1 or more

17 1 1 or more

17 Odd1 or more

1 7 Even 1 or more

Pa ri ty

(bit)

Stop

(bit)

1 7 None 2

66

Telephone line types

This internal modem can be connected to 2-wire analog subscriber
telephone lines (POTS lines) only.

Connectable lines (2-wire)

❖ Ordinary analog telephone lines with direct connection

❖ Corporate analog lines connected to a PBX

❖ Analog lines connected to a PBX, which, for example,

provide dial tone when the handset is picked up and permit
outgoing calls by dialing 9.

Unconnectable lines (4-wire)

❖ Business or home telephones that are connected to a key

service unit or a PBX.

Communication Conditions

67

WARNING: These are digital lines that can damage the
modem.

Lines that require pressing the (Line) button, for example “0,”
before dialing.

Dial modes

There are two types of dial modes, pulse dial and tone dial.
Generally, pulse dial lines are associated with rotary phones, but
there may be cases where a push button phone is connected to a
pulse dial line, so it is not possible to identify the type of line
simply by looking at the phone. If you are not sure what type of
line you are using, check an ordinary direct line by the following
AT command, where n is the outside number:

ATDTn Enter

68

Communication Conditions

If you connect to the dialed number, the line is tone dial type. If
you do not get a connection, it is pulse dial type.

The command ATDP will connect a pulse line.

Glossary

Acronyms

bps or BPS:Bits per Second

COM1: Communications Port 1 (serial port)

COM2: Communications Port 2 (serial port)

CPU:Central Processing Unit

FCC: Federal Communications Commission

FTP: File Transfer Protocol

GND: Ground

HDD: Hard Disk Drive

HTML: HyperText Markup Language

I/O: Input/Output

IRQ: Interrupt Request

ISA: Industry Standard Architecture

KB:Kilobyte

LAN:Local Area Network

LBA: Logical Block Addressing

69

70

Glossary

LFB: Linear Frame Buffer

LPT1: Line Printer Port 1 (parallel port)

MB: Megabyte

MIPS: Millions of Instructions per Second

PBX: Private Branch Exchange

PCI: Peripheral Component Interconnect

PIO: Programmed Input/Output

RFI: Radio Frequency Interference

ROM: Read-Only Memory

RTC: Real-Time Clock

SIMM: Single Inline Memory Module

SPB: Synchronous Pipeline Burst (cache)

UART: Universal Asynchronous Receiver/Transmitter

URL: Universal Resource Locator

A

USB: Universal Serial Bus

VCR: Video Cassette Recorder

VESA: Video Electronics Standards Association

WSS: Windows Sound System

WWW: World Wide Web

Auto reliable mode: This mode connects to a remote station by MNP or

V.42 if the remote modem accepts either of these protocols.
Otherwise, it connects in normal mode.

address: A number that identifies a location in the computer’s memory

or on disk. It tells the computer where to find information such as
the name of a file or a value for processing. A device may use a
specific memory address to transfer information to and from the
computer. See also hexadecimal.

alphanumeric: Consisting of numbers, symbols and letters you can type

or print.

Glossary

71

American National Standards Institute (ANSI) character set: The set of

characters available in Microsoft Windows (or other operating
system). The character set includes letters, numbers, symbols and
foreign language characters.

American Standard Code for Information Interchange (ASCII): A set of

256 binary codes that represent the most commonly used letters,
numbers and symbols. See also binary.

animation: A technique of imparting motion to items, either drawings or

inert objects.

application: A computer program that you use to perform tasks of a

specific type. Applications include word processors, spreadsheets
and database management systems. See also program.

asynchronous: A type of data transmission in which information is sent

at variable time intervals. To indicate when a transmitted character
begins and ends, it is preceded by a start bit and followed by an
optional parity bit and one or two stop bits. See also synchronous.

B

baud (baud rate): The speed at which communications devices such as

printers, terminals, and modems transmit information. Information
travels as a series of electronic signals. The baud rate measures the
rate of change in these signals. This is not necessarily the same as
bits per second, although the two are related. It is named for Emil
Baudot, a pioneer in printing telegraphy. See also bits per second.

Bell Standard: A series of communication procedures for telephone lines

and other analog data transmission lines standardized by AT&T
(American Telephone & Telegraph).

bit: The basic unit of information used by the computer, a bit may be

either 1 or 0. While an individual bit cannot contain a significant
amount of information, by combining bits into larger units, such as
bytes (a group of eight connected bits), your computer can deal with
huge blocks of data. See also byte.

bits per second (BPS): A way of measuring the speed at which

information is passed between two devices. This is the basic
measure used in modem communications. This is similar, but not
identical, to the baud rate. See also baud.

72

Glossary

buffer: An area of memory where information is held until it can be

processed. Buffers are frequently used to compensate for the fact
that some parts of the system are faster than others. For example, the
computer sends information to a printer much faster than even the
fastest printer can handle it. A print buffer stores printer information,
enabling the computer to continue with other tasks. As the printer
prints a page, it looks in the buffer to see what to do next.

bus: An electrical circuit that connects the microprocessor with other

parts of the computer, such as the video adapter, disk drives and
ports. It is the highway along which data flows from one device to
another. See also local bus.

busy: A code indicating the number called is busy.

byte: A sequence of eight bits. A byte is the smallest addressable unit of

data. Each byte represents an integer up to 255 in decimal (11111111
in binary, or FF in hexadecimal), or a character (such as a letter,
numeral, or other symbol). See also binary, bit, gigabyte,
hexadecimal, kilobyte, megabyte.

C

carrier: A modem converts the digital signals of the personal computer

into analog signals to send them through the telephone line. The
analog signals are “carrier,” because they transport the data. The
analog frequency is determined by the individual communication
specifications.

capacity: The amount of information that can be stored in a computer’s

memory or on a storage device such as a hard disk, diskette, or
CD-ROM. Capacity is usually measured in terms of kilobytes (KB),
megabytes (MB) or gigabytes (GB). See also gigabyte, kilobyte,

megabyte.

checksum: A method of checking data errors. Data is divided into blocks,

and the total of the data in those blocks is checked to determine
whether the data has been correctly transmitted. The total value is
called checksum.

character: Any letter, number or symbol you can use on the computer.

Some characters are non-printing characters, such as a paragraph
break in a word-processing program. A character occupies one byte
of computer storage.

Glossary

73

Class 1: A standard for fax transmission. The Toshiba internal modem

supports class 1.

choose: To use the mouse or keyboard to select a menu item, a button or

an icon.

click: To press and release a mouse button. In Windows, refers to the left

mouse button, unless otherwise stated.

COM1 and COM2: Names that the operating system gives the

computer’s serial ports to distinguish between them.

commands: Instructions that tell the computer and its devices what to do.

You can enter commands individually using the keyboard or
pointing device or combine them into macros or programs.

Command state: A state in which data from the personal computer is

received as commands to control the internal modem. Data from the
personal computer will not be output to the telephone line.

Compression: The translation of data (video, audio, digital or a

combination) to a more compact form for storage or transmission.
In computer terms, files are compressed by removing repetitive and
blank characters. Depending on the type of file, this can result in a
size reduction of over 90%. Modems use compression to reduce the
amount of time needed to send or receive a file.

D

Configuration: 1) The set of components in a computer system (such as

memory, printers and disk drives). 2) How parts of the system are
set up. For example, the configuration of the serial port includes the
baud rate, parity, data bits and stop bits.

CTS signal: A Clear to Send signal is an RS-232C standard that indicates

the modem is ready for transmission.

DAA: Data Access Arrangement is a circuit that isolates a device from

phone lines.

data: Information that a computer can process. The word “data” is

actually plural for “datum,” meaning a single piece of information.

data bits: A data communications parameter controlling the number of

bits used to represent a character. If data bits = 7, the computer can
generate 128 unique characters, if data bits = 8, the computer can
generate 256 unique characters.

74

Glossary

DCE (Data Communications Equipment or Data Circuit-terminating

Equipment): A device that establishes, maintains and terminates a

session on a network. It may also convert signals for transmission. It
is typically the modem.

DCD signal: This signal tells the personal computer whether the modem

is receiving the carrier from the opposite station

DTE (Data Terminating Equipment): A communications device that is

the source or destination of signals on a network. It is typically a
terminal or computer.

dial tone: The tone that is heard from the handset when it is picked up

dial mode: Dial mode covers pulse dial and tone dial. Pulse dial means

turning the dial or pressing the buttons to send pulse signals to
connect to the called party. Tone dial means pressing the button to
send tone signals to connect the modem to the called party.

download: 1) To receive a file from another computer through a modem.

2) To transmit font data from the computer to a printer. See also
upload.

E

DSP: A digital signal processor is a chip designed for real-time

applications. DSP techniques are used in PC processors as well as
media engines. For example, some high-end notebooks use a DSP
chip to provide Sound Blaster emulation for the internal modem as
well.

DSR signal: This signal tells the personal computer whether the modem

is ready for communication.

DTR signal: This signal tells the modem whether the personal computer

is ready for communication.

duplex: The method used to transmit data in both directions between two

devices. Synonymous with full duplex. See also half duplex, full

duplex.

echo: Displays keyboard entry on the computer terminal.

EIA: Electronic Industries Association is a manufacturers group that sets

standards for data communications equipment.

error control: Detection of errors in data communication. Requests

retransmission of data in which errors were found.

Glossary

75

escape: 1) To cancel the task currently in progress. 2) A code (ASCII

code 27, generated by the Esc key) telling the computer that what
follows are commands, not data. Used with peripheral devices such
as printers and modems.

Error control: Detection of errors in data communication. Requests

retransmission of data in which errors were found.

Escape control: This code is used to return to the command state without

disconnecting the line when the internal modem is online.

F

G

FIFO: First-In/First-Out means the first data that enters a buffer is the

first to be retrieved.

Fall ba ck : Reduction of a modem’s speed. If the remote modem cannot

communicate as fast as the local modem, the local modem will
reduce its speed.

firmware: A set of instructions built into a chip to control its activities.

Flow control: Flow control ensures smooth data communication. If

operating speed differs between the personal computer and modem
or between your modem and a remote modem and if the remote
station runs short of buffer capacity, a transmission halt request is
sent from the receiver to the transmitter. When the receiver has
enough buffer capacity to resume receiving data, a transmission
restart request is sent. There are two ways of flow control, XON and
OFF control codes and CTS and RTS signals.

frequency: The number of times a signal repeats an identical cycle within

a certain time period.

full duplex: A type of data transmission in which data flows between two

devices in both directions simultaneously. See also half duplex.

gigabyte (GB): A unit of data storage equal to 1,073,741,824 bytes (1024

x 1024 x 1024 bytes). See also byte.

Guard time: An interval before and after an escape sequence that

prevents the modem from interpreting the escape sequence as data.

H

half duplex: A type of data transmission in which data flows between

two devices in one direction at a time. See also full duplex.

76

Glossary

handshake: After a telephone line is connected from one station to

another, some signals are exchanged according to the ITU-T or Bell
standard to confirm that the standard is the same between the calling
and called stations prior to starting data communication between
them. This exchange of signals is called handshake.

hangup: Hangup means disconnecting a telephone line to terminate

communication

I

K

M

input: Information received by a computer from a storage device such as

a disk, or an input device such as the keyboard.

input/output (I/O): Input and output are two of the three functions that

computers perform (the other is processing). Input/Output describes
the interrelated tasks of providing information to the computer and
providing the results of processing to users. I/O devices include
keyboards (input) and printers (output). A disk drive is both an input
and an output device, since it can both provide information to the
computer and receive information from the computer.

ITU-T Standard: A series of communication procedures for telephone

lines and analog data transmission standardized by ITU
(International Telecommunications Union, formerly CCITT).

keyboard: The device you use to type information into the computer.

Each key on the keyboard is a switch that is activated when you
press it. The switch sends a specific code, representing the character
printed on the key, to the processor.

kilobyte (KB): A unit of data storage equal to 1024 bytes. Its

abbreviations (K and KB) are taken from the Greek word kilo,
meaning 1000, although the abbreviation refers to 1024, or 2 raised
to the 10th power. See also byte.

megabyte (MB): A unit of data storage equal to 1024 KB. From the

Greek work mega for million, one megabyte is actually 1,048,576
bytes (1024 x 1024 bytes). See also byte.

MIPS (Millions of Instructions Per Second): A computer processor’s

performance.

Glossary

77

modem: A device for transmitting computer information over telephone

lines. A modem converts (mo
transmission and also converts (dem
receives back to digital format. Many modems also interpret and
execute commands received from the computer.

modem port: The port to send and receive data to and from the modem of

a remote station.

MNP: A protocol developed by Microcom, a modem manufacturer in

the United States, which with an error correcting function built into
the modem itself corrects errors in the modem.

dulates) digital information for

odulates) information it

N

O

P

Normal mode: Error correction is not made by MNP or V.42, but even if

serial port speed is different from modem port speed, the buffers in
the modem and its flow control function permit communication
without changing their speeds.

on line: A functional state in which a device is ready to receive or

transmit information.

online: Available through the computer. Online may refer to information

on the hard disk, such as online documentation or online help, or a
connection, through a modem, to another computer or the Internet.

On hook/Off hook: On hook means the “handset is on the telephone,”

and off hook means it is off. The line is disconnected from the
internal modem when the handset is on hook, and connected to the
internal modem when it is off hook.

parity: A method in serial communications of making sure that the

information received is the same as the information that was sent. It
consists of adding an error detection bit to a group of data bits,
making the sum of the bits either odd or even. When you’re using a
modem to connect to another computer, you can set parity to none,
odd or even. In general, you should set parity to none, unless you’re
requested to do otherwise.

Private Branch Exchange (PBX): An automatic digital telephone

switching system that enables users within an organization to place
calls to each other without going through the public telephone
network. Users can also place calls to outside numbers. Do not

connect the Toshiba internal modem to a digital PBX line, or the
modem will be damaged.

78

Glossary

protocol: A set of rules and conventions that makes it possible to transfer

information between computers. If you’re transmitting a file, both
modems must use the same protocol—just as two people talking on
the telephone must speak the same language to communicate
effectively. Examples of modem protocols are V.34, V.42, and V.90.

Public line: A line served by a telephone company to be connected to an

opposite station via the exchange.

Pulse dialing: A dialing method that uses pulses instead of tones to

generate a telephone number. Generally associated with rotary dial
phones, although some push-button phones can be used on pulse
lines.

R

S

Reliable mode: Reliable mode is for error-free communication by MNP

or V.42.

Result code: This code returns to the computer the results of executing a

command sent from it to the internal modem in characters or
numeric values.

RJ11: A modular telephone connector used on most telephone networks

and direct-connect modems.

RTS signal: A Request to Send signal is an RS-232C standard that

indicates the modem is ready to receive data.

RS-232-C: The standard defining control, data and status signals for

cables allowing asynchronous communication with computers,
printers, and other peripheral devices.

serial: The handling of data bits one after the other.

serial communications: A communications technique that uses as few as

two interconnecting wires to send bits one after another.

serial interface: An interface between systems or system components in

which information is transmitted sequentially, one bit at a time. The
transmitted bits are reassembled at the receiving component. A
modem uses a serial interface.

serial port: A communications port (COM1 or COM2) to which you can

connect a serial device, such as a modem, a mouse or a serial printer.

stop bit: In asynchronous serial communications, one or more bits

indicating the end of a block of characters.

Glossary

79

S-Register: The S-Register stores the parameters for various commands

and modem operations.

synchronous: Having a constant time interval between successive bits,

characters or events. Synchronous data transmission requires both
the sending and receiving devices to use special synchronizing
characters to correct variations in timing between the devices. See
also asynchronous.

T

U

X

Test function: When normal communication is not possible, this function

checks the modem, personal computer, and telephone lines to
determine if they are normal.

Tone dialing: A dialing method that uses tones instead of pulses to

generate a telephone number. Generally associated with push-button
phones, although some push-button phones can be connected to
pulse lines.

upload: To send a file to another computer through a modem. See also

download.

UART: Universal Asychronous Receiver Transmitter is the circuit

interface between the modem and computer. It receives serial bit
data from the modem and converts it into bytes for the computer;
and it converts byte data from the computer into bit data for serial
communication.

XON/XOFF: flow control: A protocol used by devices receiving data. It

uses two signals: transfer ON and transfer OFF. The signals are
controlled by software.

Index

Numerics

56K technology xiii

A

analog/loopback test 59
answer command 14
AT command set

result codes 46

AT commands

answer command 14
communication standard setting

14
data carrier detect 25
data compression control 33
data terminal ready (DTR) 26
dial a telephone number 15
dial tone detect 24
display result codes 23
echo command 16
error control mode selection 31
escape sequence 14
extended result codes 24
format 13

guard tone control 27
hook control 16
load factory settings 26
local flow control selection 27, 32
monitor speaker mode 20
monitor speaker volume 20
MS command 34
N modulation handshake 21
protocol result code 32
recall stored profile 25
repeat last command string 14
request ID information 17
result code control 22
result code option 23
result code selection 23
return to online data mode 21
select pulse dial make/break ratio

27
select pulse dialing 22
select tone dialing 22
self-test commands 28
store current configuration 30
store telephone number 31
V.90 enable/disable 33

80

Index

81

view active configuration and

stored profile 28

C

call

receiving 9

terminating 9
Clear To Send 10
communication standard setting 14
communications

dial mode types 67

facsimiles 11

handshake commands 54

modes 54

parameters 66

protocols supported xv

specifications 63

telephone line types 67
connecting internal modem 5, 6
connecting to a telephone line 8
connection procedures 5
CTS/RTS 10

D

data carrier detect 25
data compression 57
data compression control 33
data terminal ready (DTR) 26
default settings 1
diagnostics 2
dial a telephone number 15
dial tone detect 24
disconnecting the internal modem 7
display result codes 23
downsteam rate 45

E

echo command 16
error control mode selection 31
escape sequence 14

extended result codes 24

F

fax communication 11
features

internal modem xiii

flow control 54

computer to modem 54
modem port 55, 56
modem to modem 54
serial port 55

computer to modem 55
software 55
two-way 56

G

guard tone control 27

H

handshake 21
handshake commands 54
hardware setup 1
hook control 16

I

icons

definitions xviii

internal modem

communications protocols xv
connecting 6
connection procedures 5
disconnecting 7
features xiii

L

load factory settings 26
local flow control selection 27, 32
loopback test 60