Multitech MultiModem DID MT5634ZBA-DID User manual

MT5634ZBA-DID
Data/Fax/DID Modem
User Guide

User Guide
Product Number S000234A Revision A
MultiModemDID (MT5634ZBA-DID)
Copyright
Copyright © 2002 by Multi-Tech Systems, Inc.
All rights reserved. This publication may not be reproduced, in whole or in part, without prior expressed
written permission from Multi-Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no representations or warranties with respect to the contents hereof and
specifically disclaims any implied warranties of merchantability or fitness for any particular purpose. Fur-
thermore, Multi-Tech Systems, Inc. reserves the right to revise this publication and to make changes in
the content hereof without obligation of Multi-Tech Systems, Inc. to notify any person or organization of
such revisions or changes.
Record of Revisions
Revision Date Description
A 09/18/02 Supports V.92. Initial release of manual for publication on CD.
Trademarks
MultiModemZBA, Multi-Tech, and the Multi-Tech logo are trademarks of Multi-Tech Systems, Inc.
Adobe and Acrobat are trademarks of Adobe Systems Incorporated. MNP is a trademark of Microcom,
Inc. Microsoft, Windows, Windows 95, Windows 98, Windows Me, Windows NT, Windows 2000, and
Windows XP are either registered trademarks or trademarks of Microsoft Corporation in the United States
and/or other countries. All other brand and product names mentioned in this publication are trademarks
or registered trademarks of their respective companies.
Patents
This device is covered by one or more of the following patents: 6,031,867; 6,012,113; 6,009,082;
5,905,794; 5,864,560; 5,815,567; 5,815,503; 5,812,534; 5,809,068; 5,790,532; 5,764,628; 5,764,627;
5,754,589; D394,250; 5,724,356; 5,673,268; 5,673,257; 5,644,594; 5,628,030; 5,619,508; 5,617,423;
5,600,649; 5,592,586; 5,577,041; 5,574,725; D374,222; 5,559,793; 5,546,448; 5,546,395; 5,535,204;
5,500,859; 5,471,470; 5,463,616; 5,453,986; 5,452,289; 5,450,425; D361,764; D355,658; D355,653;
D353,598; D353,144; 5,355,365; 5,309,562; 5,301,274. Other patents pending.
World Headquarters
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, MN 55112
U.S.A
Telephone [phone] or [phone]
Fax [phone]
Technical Support [phone]
Internet http://www.multitech.com

Contents
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MultiModemDID User Guide
Table of Contents
Chapter 1 - Introduction and Description......................................................................... 5
Introduction........................................................................................................... 5
Features ............................................................................................................... 5
We Supply ............................................................................................................ 6
Safety ................................................................................................................... 6
Chapter 2 - Installation .................................................................................................... 7
Step 1: Assemble the Modem .............................................................................. 7
Step 2: Connect the Modem to Your System ....................................................... 7
Step 3: Install the Modem Driver .......................................................................... 8
Removing Your Old Modem from Windows.......................................................... 8
Chapter 3 – Operation................................................................................................... 10
Front Panel of the MultiModemDID Modem ....................................................... 10
DID Operation..................................................................................................... 11
V.92 Operation ................................................................................................... 11
Connecting to the Internet .................................................................................. 12
Dial-Up Networking............................................................................................. 12
Chapter 4 - AT Commands, S -Registers, and Result Codes ....................................... 13
AT Commands.................................................................................................... 14
V.92 Commands ................................................................................................. 28
Other Commands ............................................................................................... 30
DID Commands .................................................................................................. 32
MT5634ZBA-DID Initialization Recommendations ............................................. 32
About the Busy-Out Features and Functions ..................................................... 33
S-Registers ......................................................................................................... 36
Result Codes ...................................................................................................... 39
Chapter 5 - Remote Configuration ................................................................................ 41
Basic Procedure ................................................................................................. 41
Setup .................................................................................................................. 41

Contents
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MultiModemDID User Guide
Chapter 6 - Troubleshooting.......................................................................................... 43
None of the Indicators Light................................................................................ 43
The Modem Does Not Respond to Commands.................................................. 43
The Modem Dials But Cannot Connect .............................................................. 44
The Modem Disconnects While Online .............................................................. 45
The Modem Cannot Connect When Answering ................................................. 45
The Modem Doesn’t Work with Caller ID............................................................ 45
Fax and Data Software Can’t Run at the Same Time ........................................ 45
DID Troubleshooting........................................................................................... 46
Appendix A – Regulatory Compliance........................................................................... 47
FCC Part 68 Telecom ......................................................................................... 47
FCC Part 15........................................................................................................ 48
Fax Branding Statement ..................................................................................... 48
Canadian Limitations Notice ............................................................................... 48
Industry Canada ................................................................................................. 48
Appendix B – Technical Specifications ......................................................................... 49
Appendix C - Warranty and Repairs ............................................................................. 50
Appendix D - Upgrading the Modem’s Firmware .......................................................... 52
Appendix E - Installing a Modem Under Linux .............................................................. 54
Introduction......................................................................................................... 54
Standard Linux Serial Port Definitions ................................................................ 54
Installation .......................................................................................................... 54
Setup .................................................................................................................. 54
Appendix F - Technical Support .................................................................................... 56
Index .................................................................................................... 57

Chapter 1 - Introduction and Description
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MultiModemDID User Guide
Chapter 1 - Introduction and Description
Welcome to the world of data communications. You have acquired one of the finest intelligent data and
fax modems available today from one of America’s oldest and most respected modem manufacturers:
Multi-Tech Systems, Inc. This User Guide will help you install, configure, test, and use your modem.
Introduction
The MultiModemDID combines Direct Inward Dial (DID) with Super G3 V.34/33.6K bps fax and V.92 data
modes of operation. Direct Inward Dial allows the user to use a block of telephone numbers larger than
the number of physical telephone lines for direct dialing to extensions. When combining DID with inbound
fax calls to a fax server, each user on the fax server can have faxes automatically routed to them at their
client computer desktop.
DID fax routing assigns a unique fax number for every network user or network device (such as a
printer). Senders simply dial a typical telephone number - no special procedures are required. The fax
server automatically delivers the incoming fax to the user over the local area network.
Users get improved efficiency and security, since their faxes are delivered by the network fax server to
the client desktop as soon as they are received. Time-wasting trips to the fax machine are eliminated and
employees are more productive. In addition, DID offers a higher degree of security for both the sender
and the recipient since faxes are not left unattended at a central fax machine.
The MT5634ZBA-DID utilizes Super G3 V.34 fax speeds of 33.6K bps. Now, computer-based fax servers
can achieve the Super G3 speeds found in dedicated fax machines. The MT5634ZBA-DID also supports
T.31 Annex B and T.32 Annex C, which allows the higher V.34 speeds to operate with Class 1.0 and
Class 2.1 code sets. In addition, “on-the-fly” two-dimensional fax data compression plus support for error
correction mode (ECM) increase the performance of the MT5634ZBA-DID to levels previously only found
in expensive fax boards and dedicated fax machines.
To implement DID fax routing you must purchase fax server application software that supports Multi-Tech
DID commands and DID routing, and obtain an analog DID trunk line which supports the inbound fax
calls and a regular loop-start line for outbound fax transmission.
Features
·One Direct Inward Dial (DID) port
·Super G3 V.34/33.6K bps fax communication
·T.31 Annex B Class 1.0 and T.32 Annex C Class 2.1 fax commands
·Error Correction Mode (ECM) provides fast and reliable fax transmissions
·Supports Wink-start, Immediate-start and Delay dial service types
·V.92/56K data mode
·V.44 compression improves data throughput rates
·V.42 error correction
·Flash memory for easy updates
Plug and Play operation.
Interactive automatic dialing and command mode configuration.
In standard mode, you can store up to four command lines or telephone numbers of up to 40
characters each in the modems’ nonvolatile memory.
Pulse- or tone-dials and recognizes dial tones and busy signals for reliable call-progress detection.
Detects AT&T calling card tones.
Caller ID.
Remote configuration.
Incorporates self-resetting lightning protection.

Chapter 1 - Introduction and Description
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MultiModemDID User Guide
We Supply
•An MT5634ZBA-DID modem
•A set of four self-adhesive plastic feet
•A power supply
•A 9-pin to 9-pin serial cable
•Two RJ-11 telephone cables
•A printed Quick Start Guide
•A CD containing modem drivers, a User Guide, and Adobe Acrobat Reader.
You Supply
•A computer with an available serial port
•A nearby AC power outlet
•A nearby phone line jack
•A nearby analog DID trunk line with a block of associated DID telephone numbers
Safety
1. Use this product only with UL and cUL listed computers.
2. To reduce the risk of fire, use only 26 AWG (.41mm) or larger telephone wiring.
3. Never install telephone wiring during a lightning storm.
4. Never install a telephone jack in wet locations unless the jack is specifically designed for wet
locations.
5. Never touch uninsulated telephone wires or terminals unless the telephone line has been
disconnected at the network interface.
6. Use caution when installing or modifying telephone lines.
7. Avoid using a telephone during an electrical storm. There is a risk of electrical shock from
lightning.
8. Do not use a telephone in the vicinity of a gas leak.

Chapter 2 - Installation
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MultiModemDID User Guide
Chapter 2 - Installation
Step 1: Assemble the Modem
The only assembly required is to mount the feet on the bottom of the modem. Simply peel the four self-
adhesive plastic feet off the backing strip and press them into the recesses on the bottom of the modem.
Step 2: Connect the Modem to Your System
Turn off your computer. Place the modem in a convenient location, and then connect it to your
computer’s serial port, the phone line, AC power, DID line, and your phone.
Connect the Modem to Your PC
Plug one end of the serial cable into the connector on the modem, and plug the other end into a
serial port on your computer, such as COM1 or COM2.
Connect the Modem to the Telephone Line
Plug one end of the phone cable into the modem’s LINE jack and the other end into a phone wall
jack. The phone cable is included with your modem.
Note: The LINE jack is not interchangeable with the PHONE jack. Do not plug the phone into the LINE
jack or the line cable into the PHONE jack.

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MultiModemDID User Guide
(Optional) Connect the Modem to the Phone
For voice-only calls, plug a phone into the modem’s PHONE jack.
Connect the Modem to the AC Power Outlet
Make sure the power is switch is OFF. Plug the DC power transformer into a power outlet or power
strip. Plug the other end into the PWR jack on the modem. The DC power transformer is included
with your modem.
CAUTION: Use only the DC power transformer supplied with the modem. Use of any other
transformer voids the warranty and can damage the modem.
Connect the Modem to the DID Line
Plug one end of the phone cable into the modem’s DID jack and the other end into an analog DID
trunk line jack. The DID Line cable is included with your modem.
CAUTION: The DID Line cable has a 4-pos RJ11 on one side and a 6-pos on the other. Never plug
the DID connector into a standard POTS Line. This may damage the modem or the central office
equipment. Use only an analog DID Line.
Power-on Test
Test the modem by turning it on (an on-off switch is located on the side panel). When you apply
power, the modem performs a diagnostic self-test. The 56 indicator lights, and if a terminal program
is running, the TR indicator also lights. If this does not happen, check that the power switch is on,
the power supply is solidly connected, and the AC outlet is live. If these measures do not work, see
the Troubleshooting chapter.
Step 3: Install the Modem Driver
1. Make sure your modem is connected properly, and then turn on your computer. Windows should
detect your new modem and open the Install New Modem wizard.
Note: If Windows cannot find a modem, your modem may be turned off, it may be plugged into the
wrong connector on your computer, or the serial cable may be faulty. See “None of the LEDs Light
When the Modem Is Turned On” and “The Modem Does Not Respond to Commands” in the
“Troubleshooting” chapter in the complete User Guide.
2. Insert the MT5634ZBA-DID CD into your CD-ROM drive, and then click OK.
3. Windows installs the modem driver.
4. Click Finish to exit
Removing Your Old Modem from Windows
When your new modem replaces another modem, the old modem installation remains in Windows after
you install the new modem, and the old modem is still selected in HyperTerminal and other Windows
applications. Although you can change the application connection descriptions one at a time, it is easier
to force Windows applications to use the new modem by removing the old modem from Windows.

Chapter 2 - Installation
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MultiModemDID User Guide
From Windows 2000, XP
1. Click Start | Settings |Control Panel.
2. Double-click the Phone and Modems icon and click on the Modems tab.
3. In the list box, select the old modem.
4. Click Remove, then click Close.
5. The next time you dial a HyperTerminal connection, it will select your new modem and ask you
to confirm the selection.
From Windows 98, Me
1. Click Start | Settings |Control Panel.
2. Double-click the Modems icon to open the Modems Properties sheet.
3. In the list box, select the old modem.
4. Click Remove, then click Close.
5. The next time you dial a HyperTerminal connection, it will select your new modem and ask you
to confirm the selection.

Chapter 3 - Operation
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MultiModemDID User Guide
Chapter 3 – Operation
Front Panel of the MultiModemDID Modem
The MT5634ZBA-DID modem has 10 LED indicators on the front panel that provide information about
how your modem is operating: status, configuration and activity.
TD
Transmit Data - The TD LED flashes when the modem is transmitting data to another modem.
RD
Receive Data - The RD LED flashes when the modem is receiving data from another modem.
CD
Carrier Detect - The CD LED lights when the modem detects a valid carrier signal from another
modem. It is on when the modem is communicating with the other modem and off when the link is
broken.
56
56 - The 56 LED is a 56K mode indicator. It lights whenever the modem is set for or connects
using the V.90 or V.92 protocols.
33
33 - The 33 LED is a V.34 mode indicator. It lights whenever the modem connects using the V.34
protocol.
OH
Off-Hook - The OH LED lights when the modem is off-hook, which occurs when the modem is
dialing, online, or answering a call. The LED flashes when the modem pulse-dials.
TR
Terminal Ready - The TR LED lights when a communications program is using the modem. It
means the modem is ready for an outgoing or incoming call. It goes off when the communications
program disconnects the serial port. When it goes off, a connected modem will also disconnect.
EC
Error Correction (V.42) - The EC LED lights continuously when the modem is in V.42 error
correction mode, and it flashes when compression is achieved.
FX
Fax - The FX LED lights when the modem is in fax mode.
DID - The DID LED lights when there is an incoming call on the DID line.

Chapter 3 - Operation
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MultiModemDID User Guide
DID Operation
Direct Inward Dialing (DID) uses an analog trunk line to route several phone numbers to one line. The
MT5634ZBA-DID modem has four ports, an RS232 serial port, two RJ11 ports for connection to a POTS
line and an auxillary phone, and a 4 position RJ12 for connection to the DID analog trunk.
Note: The DID and POTS ports cannot operate simultaneously.
On a DID line the roles of the central office and the DID modem are somewhat reversed. The DID
modem must provide a DC voltage, around 48V, to the line. When there is an incoming call, the central
office will complete a loop and draw current from the DID modem.
On a standard POTS line, the central office provides the DC voltage and the user will close the loop by
lifting the handset of a phone or making a call with a standard modem.
There are two critical points about the DC voltage:
1. The central office is sensitive to the DC polarity. TiP (positive) and riNg (Negative) must be
connected to the line from the central office with the proper polarity. If not, callers will receive an
immediate busy signal or may be allowed to make a short connection but become unexpectedly
disconnected after a short time.
2. The DC voltage should be applied by the modem at all times, even when not in use. Occasionally,
the central office will check the line; and, if a voltage is not sensed, the line will be put out of
service. A call to the phone company will be required to get the line back in service.
The DID modem may use line reversals to signal the central office to send digit information or open the
channel to the calling party depending on the start protocol of the DID line. The central office will forward
several of the last digits of the incoming call to the DID modem through one of three formats, DTMF, MF,
or pulse signaling.
V.92 Operation
Because the V.92 protocol is new and still largely unsupported by central servers, some features are
disabled by default in the initial release of the MT5634ZBA-DID modem. This section describes the status
of the V.92 features in the initial release. Please note that the V.92 special features require connection to
a V.92-capable server.
General. The V.92 protocol is enabled by default. If the MultiModemZBA-DID detects another
V.92 modem during the handshake phase, they will connect in V.92 mode; otherwise, they will
connect in V.90 mode or the highest mutually acceptable mode. The AT command that controls
this is +MS=.
Commands. AT commands specific to the V.92 protocol and the new V.44 compression protocol
begin with the plus character (+). These commands are in this manual. Also, the S109 register
has been modified to support V.92.
PCM Upstream. PCM Upstream is disabled by default. To upload files at speeds above 33.6
kbps, you must enable PCM Upstream using the command +PIG=1. Please note that this requires
connection to a V.92-capable server. Also, please note that since upload speeds are affected by
line conditions, meeting the previous requirements cannot guarantee speeds above 33.6 kbps.
Quick Connect. Quick Connect, which shortens the handshake time with another V.92 modem, is
disabled by default. To enable it, use the command +PQC=0. Quick Connect speeds connect
times by skipping the line test during the handshake and using the configuration from the last data
connection. Quick Connect works best when line conditions are consistent from call to call. If line
conditions are variable, enabling Quick Connect can actually increase the connect time slightly.
Modem on Hold (is not available at this time).

Chapter 3 - Operation
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MultiModemDID User Guide
Connecting to the Internet
Your Multi-Tech modem is your gateway to the Internet and the World Wide Web. To access the Internet
and Web via your modem, you must establish a dial-up account with an Internet service provider (ISP).
To locate an ISP near you, look in a local directory or computer publication. Your ISP should provide you
with the following information:
User name (also called user ID)
Password
Access number (the number you call to connect to the server)
Host name and/or domain name
Domain Name Server (DNS) server address
If, besides the Web, you use the Internet for e-mail and newsgroups, your ISP should also provide you
with the following information:
E-mail or POP mail address
POP server address
Mail or SMTP address
News or NNT server address
Dial-Up Networking
Before you can connect to the Internet, you must set up a remote-node client program on your computer.
The Windows version is called Dial-Up Networking. Dial-Up Networking establishes your connection to
the ISP’s server, which is the shared computer that manages calls from clients (your computer) to the
Internet. Most, if not all, Windows browsers start Dial-Up Networking automatically when you open them.
For instructions on how to set up Dial-Up Networking, consult your ISP or your operating system’s online
help or printed documentation. Many ISPs include, as part of their service, a program that will install and
configure Dial-Up Networking automatically for you.

Chapter 4 - AT Commands, S-Registers, Result Codes
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MultiModemDID User Guide
Chapter 4 - AT Commands, S -Registers,
and Result Codes
AT commands are used to control the operation of your modem. They are so called because each
command must be preceded by the characters AT to get the AT tention of the modem.
AT commands can be issued only when the modem is in command mode or online command mode. The
modem is in command mode whenever it is not connected to another modem. The modem is in data
mode whenever it is connected to another modem and ready to exchange data. Online command mode
is a temporary state in which you can issue commands to the modem while connected to another
modem. To put the modem into online command mode from data mode, you must issue an escape
sequence (+++) followed immediately by the AT characters and the command, e.g., +++ATH to hang up
the modem. To return to data mode from online command mode, you must issue the command ATO.
To send AT commands to the modem you must use a communications program, such as HyperTerminal
or the PhoneTools communications program included with your modem. You can issue commands to the
modem either directly, by typing them in the terminal window of the communications program, or
indirectly, by configuring the operating system or communications program to send the commands
automatically. Fortunately, communications programs make daily operation of modems effortless by
hiding the commands from the user. Most users, therefore, need to use AT commands only when
reconfiguring the modem, e.g., to turn autoanswer on or off.
The format for entering an AT command is AT Xn , where X is the command and n is the value for the
command, sometimes called the command parameter . The value is always a number. If the value is zero,
you can omit it from the command; thus, AT&W is equivalent to AT&W0. Most commands have a default
value, which is the value that is set at the factory. The default values are shown in the “AT Commands”
section, which begins on the next page.
You must press ENTER to send the command to the modem. Any time the modem receives a command, it
sends a response known as a result code . The most common result codes are OK , ERROR , and the
CONNECT messages that the modem sends to the computer when it is connecting to another modem.
For a table of valid result codes, see “Result Codes” at the end of this chapter.
You can issue several commands in one line, in what is called a command string . The command string
begins with AT and ends when you press ENTER. Spaces to separate the commands are optional; they
are ignored by the command interpreter. The most familiar command string is the initialization string ,
which is used to configure the modem when it is turned on or reset, or when your communications
software calls another modem.

Chapter 4 - AT Commands, S-Registers, Result Codes
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MultiModemDID User Guide
AT Commands
Command: AT Attention Code
Values: n/a
Description: The attention code precedes all command lines except A/ and
the escape sequence.
Command: ENTER Key
Values: n/a
Description: Press the ENTER or RETURN key to execute most commands.
Command: A Answer
Values: n/a
Description: Answers an incoming call before the final ring.
Command: A/ Repeat Last Command
Values: n/a
Description: Repeats the last command string. Do not precede this
command with AT. Do not press ENTER to execute.
Command: B n Communication Standard Setting
Values: n = 0–3, 15, 16
Default: 1 and 16
Description: B0 Select ITU-T V.22 mode when modem is at 1200 bps.
B1 Select Bell 212A when modem is at 1200 bps.
B2 Deselect V.23 reverse channel (same as B3).
B3 Deselect V.23 reverse channel (same as B2).
B15 Select V.21 when the modem is at 300 bps.
B16 Select Bell 103J when the modem is at 300 bps.
Command: D s Dial
Values: s = dial string (phone number and dial modifiers)
Default: none
Description: Dial telephone number s , where s may up to 40 characters long
and include the 0 – 9 , * , # , A , B , C , and D characters, and the L,
P, T, W, S, comma (,), semicolon (;), !, @, ^and $dial string
modifiers.
Dial string modifiers:
LRedial last number. (Must be placed immediately after ATD.)
PSelect pulse-dialing until a Tis encountered. Affects current
and subsequent dialing.
TSelect tone-dialing until a Pis encountered. Affects current
and subsequent dialing.
WWait for a new dial tone before continuing to dial. (X2, X4,
X5, X6, or X7 must be selected.)
,Pause during dialing for time set in register S8.
;Return to command mode after dialing. Place at end of dial
string.
!Hook flash. Causes the modem to go on-hook for one-half
second, then off-hook again.

Chapter 4 - AT Commands, S-Registers, Result Codes
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MultiModemDID User Guide
@Wait for quiet answer. Causes modem to wait for a ring
back, then 5 seconds of silence, before processing next
part of command. If silence is not detected, the modem
returns a NO ANSWER code.
^Disable data calling tone transmission.
$Detect AT&T call card “bong” tone. The character should
follow the phone number and precede the user’s call card
number:ATDT1028806127853500$123456789.
Command: DS=
n Dial Stored Telephone Number
Values: n = 0, 1, 2
Default: none
Description: Dials a number previously stored in directory number y by the
&Zn=x command. Example: ATDS=3.
Command: E n Echo Command Mode Characters
Values: n = 0 or 1
Default: 1
Description: E0 Does not echo keyboard input to the terminal.
E1 Does echo keyboard input to the terminal.
Command: F n Echo Online Data Characters
Values: n = 0, 1
Default: 1
Description: F0 Enables online data character echo. (Not supported.)
F1 Disables online data character echo (included for backward
compatibility with some software).
Command: H n Hook Control
Values: n = 0 or 1
Default: 0
Description: H0 Goes on-hook (hangs up).
H1 Goes off-hook (makes the phone line busy).
Command: I n Information Request
Values: n = 0–5, 9, 11
Default: None
Description: I0 Displays default speed and controller firmware version.
I1 Calculates and displays ROM checksum (e.g., B399 ).
I2 Checks ROM and verifies the checksum, displaying OK or ER-
ROR .
I3 Displays default speed and controller firmware version.
I4 Displays firmware version for data pump (e.g., 17 ).
I5 Displays the board ID: software version, hardware version, and
the country ID in hexadecimal format (e.g., s0503a01V, 0, 34 ).
I9 Displays the country code in decimal format (e.g., 52 ).
I11 Displays diagnostic information for the last modem connection,
such as DSP and firmware version, link type, line speed, serial
speed, type of error correction/data compression, number of
past retrains, etc.

Chapter 4 - AT Commands, S-Registers, Result Codes
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MultiModemDID User Guide
Command: M n Monitor Speaker Mode
Values: n = 0, 1, 2, or 3
Default: 1
Description: M0 Speaker always off.
M1 Speaker on until carrier signal detected.
M2 Speaker always on when modem is off-hook.
M3 Speaker on until carrier is detected, except while dialing.
Command: N
n Modulation Handshake
Values:
n = 0 or 1
Default: 1
Description: N0 Modem performs handshake only at communication standard
specified by S37 and the B command.
N1 Modem begins handshake at communication standard
specified by S37 and the B command. During handshake,
fallback to a lower speed can occur.
Command: O n Return Online to Data Mode
Values: 0, 1, 3
Default: None
Description: O0 Exits online command mode and returns to data mode (see
+++AT<CR> escape sequence ).
O1 Issues a retrain and returns to online data mode.
O3 Issues a rate renegotiation and returns to data mode.
Command: P Pulse Dialing
Values: P, T
Default: T
Description: Configures the modem for pulse (non-touch-tone) dialing.
Dialed digits are pulsed until a Tcommand or dial modifier is
received.
Command: Q n Result Codes Enable/Disable
Values: n = 0, 1
Default: 0
Description: Q0 Enables result codes.
Q1 Disables result codes.
Command: S r = n Set Register Value
Values: r = S-register number; n varies
Default: None
Description: Sets the value of register S r to the value of n , where n is
entered in decimal format. Example: S0=1.
Command: S r ? Read Register Value
Values: r = S-register number
Default: None
Description: Reads the value of register S r and displays it in 3-digit decimal
form. For example, S2? gives the response 043 .

Chapter 4 - AT Commands, S-Registers, Result Codes
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MultiModemDID User Guide
Command: T Tone Dialing
Values: P, T
Default: T
Description: Configures the modem for DTMF (touch-tone) dialing. Dialed
digits are tone dialed until a Pcommand or dial modifier is
received.
Command: V n Result Code Format
Values:
n = 0 or 1
Default: 1
Description: V0 Displays result codes as digits (terse response).
V1 Displays result codes as words (verbose response).
Command: W
n Result Code Options
Values: n = 0, 1, 2
Default: 2
Description: W0 CONNECT result code reports serial port speed, disables
protocol result codes.
W1 CONNECT result code reports serial port speed, enables
protocol result codes.
W2 CONNECT result code reports line speed, enables protocol
result codes.
Command: X n Result Code Selection
Values: n = 0–7
Default: 4
Description: X0 Basic result codes ( e.g., CONNECT ); does not look for dial
tone or busy signal.
X1 Extended result codes ( e.g., CONNECT 46000 V42bis ); does
not look for dial tone or busy signal.
X2 Extended result codes with NO DIALTONE ; does not look for
busy signal.
X3 Extended result codes with BUSY ; does not look for dial tone.
X4 Extended result codes with NO DIALTONE and BUSY .
X5 Extended result codes with NO DIALTONE and BUSY .
X6 Extended result codes with NO DIALTONE and BUSY .
X7 Basic result codes with NO DIALTONE and BUSY .
Command: Z n Modem Reset
Values: n = 0 or 1
Default: None
Description: Z0 Resets modem to profile saved by the last &W command.
Z1 Same as Z0.
Command: &C n Data Carrier Detect (DCD) Control
Values: n = 0, 1, or 2
Default: 1
Description: &C0 Forces the DCD circuit to be always high.
&C1 DCD goes high when the remote modem’s carrier signal is
detected, and goes low when the carrier signal is not detected.
&C2 DCD drops on disconnect for time set by S18, then goes high
again (for some PBX phone systems).

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Command: &D n Data Terminal Ready (DTR) Control
Values: n = 0, 1, 2, or 3
Default: 2
Description: &D0 Modem ignores the true status of the DTR signal and responds
as if it is always on.
&D1 If DTR drops while in online data mode, the modem enters
command mode, issues an
OK , and remains connected.
&D2 If DTR drops while in online data mode, the modem hangs up.
If the signal is not present, the modem will not answer or dial.
&D3 If DTR drops, the modem hangs up and resets as if an ATZ
command were issued.
Command: &E
n XON/XOFF Pacing Control
Values:
n = 12 or 13
Default: 12
Description: &E12 Disables XON/XOFF pacing.
&E13 Enables XON/XOFF pacing. (&K4 must also be set.)
Note: &E13 has no effect if hardware control (&K3) is selected.
Command: &F
n Load Factory Settings
Values: n = 0
Default: None
Description: &F0 Loads factory settings as active configuration.
Note: See also the Z command.
Command: &G n V.22bis Guard Tone Control
Values: n = 0, 1, or 2
Default: 0
Description: &G0 Disables guard tone.
&G1 Sets guard tone to 550 Hz.
&G2 Sets guard tone to 1800 Hz.
Note: The &G command is not used in North America.
Command: &K n Flow Control Selection
Values: n = 0, 3, or 4
Defaults: 3
Description: &K0 Disables flow control.
&K3 Enables CTS/RTS hardware flow control.
&K4 Enables XON/XOFF software flow control.
Command: &Q n Asynchronous Communications Mode
Values: n = 0, 5, 6, 8, or 9
Default: 5
Description: &Q0 Asynchronous with data buffering. Same as \N0.
&Q5 Error control with data buffering. Same as \N3.
&Q6 Asynchronous with data buffering. Same as \N0.
&Q8 MNP error control mode. If MNP error control is not
established, the modem falls back according to the setting in
S36.
&Q9 V.42 or MNP error control mode. If neither error control is
established, the modem falls back according to the setting in
S36.

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Command: &S n Data Set Ready (DSR) Control
Values: n = 0 or 1
Default: 0
Description: &S0 DSR is always high (on).
&S1 DSR goes high only during a connection.
Command: &T
n V.54 Test Commands
Values:
n = 0, 1, 3 or 6
Default: None
Description: &T0 Abort. Stops any test in progress.
&T1 Initiates local analog loopback test.
&T3 Initiates local digital loopback test.
&T6 Initiates remote digital loopback test.
Note: To stop a test, you must use the escape sequence (+++AT) before typing
&T0.
Command: &V Display Current Settings
Values: n/a
Description: Displays the active modem settings, including the callback
security settings if callback security is enabled. If the setup
password has been entered, it also displays the callback
security passwords.
Command: &W n Store Current Configuration
Values: n = 0, 1
Default: 1
Description: &W0 Stores current modem settings in nonvolatile memory and
causes them to be loaded in place of the factory defaults at
power-on or following the ATZ command. See also the &F
command.
&W1 Clears user default settings from nonvolatile memory and
causes the factory defaults to be loaded at power-on or
following the ATZ command.
Command: &Z n=x Store Dialing Command
Values: n = 0, 1, 2 (callback security disabled)
x = Dialing command string
Default: None
Description: Stores dialing command x in memory location y . Dial the stored
number using the command ATDS= n . See also the #CBS n
command.
Command: \A n Select Maximum MNP Block Size
Values: n = 0, 1, 2, or 3
Default: 3
Description: \A0 64-character maximum.
\A1 128-character maximum.
\A2 192-character maximum.
\A3 256-character maximum.

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Command: \B n Transmit Break
Values: n = 0–9 in 100 ms units
Default: 3
Description: In non-error-correction mode only, sends a break signal of the
specified length to a remote modem. Works in conjunction with
the \K command.
Command: \K n Break Control
Values:
n = 0–5
Default: 5
Description: Controls the response of the modem to a break received from
the computer, the remote modem, or the \B command. The
response is different for each of three different states.
Data mode. The modem receives the break from the
computer:
\K0 Enters online command mode, no break sent to the remote
modem.
\K1 Clears data buffers and send break to the remote modem.
\K2 Same as \K0.
\K3 Sends break immediately to the remote modem .
\K4 Same as \K0.
\K5 Sends break to the remote modem in sequence with the
transmitted data.
Data mode. The modem receives the break from the remote
modem:
\K0 Clears data buffers and sends break to the computer.
\K1 Same as \K0.
\K2 Sends break immediately to the computer.
\K3 Same as \K2.
\K4 Sends break to the computer in sequence with the received data.
\K5 Same as \K4.
Online command mode. The modem receives a \B
n
command from the computer:
\K0 Clears data buffers and sends break to the remote modem.
\K1 Same as \K0.
\K2 Sends break immediately to the remote modem.
\K3 Same as \K2.
\K4 Sends break to the remote modem in sequence with the
transmitted data.
\K5 Same as \K4.