Multitech MT5656ZDX Series User manual

Model MT5656ZDX-Series
Voice/Data/Fax Modem
User Guide

User Guide
MT5656ZDX-Series
PN S000248G Revision G
This publication may not be reproduced, in whole or in part, without prior expressed written permission from Multi-Tech Sys-
tems, Inc. All rights reserved.
Copyright © 2003-4 by Multi-Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no representations or warranties with respect to the contents hereof and specifically
disclaims any implied warranties of merchantability or fitness for any particular purpose. Furthermore, Multi-Tech Systems,
Inc. reserves the right to revise this publication and to make changes in the content hereof without obligation of Multi-Tech
Systems, Inc. to notify any person or organization of such revisions or changes.
Revision Date Description
A06/17/02 Manual released
B07/15/02 Manual updated to remove K56flex from Modulation Selection (+MS).
C07/26/02 Manual updated to include registration number.
D10/22/02 Remove Fax 2 references (MT5656ZDX does not support Fax 2 commands). Move
AT Commands to a separate document. Move Fax 1 Commands to a separate
document.
E11/07/02 Remove Flash protocol information. At this point Flash is not supported.
F01/13/03 Add Fax Class 2 support and Flash protocol. Both now supported.
G11/22/04 Remove Voice Commands (they are in the AT Command document). Change
power supply to 9 volts. Remove Remote Configuration as a feature.
Trademarks
MultiModem, Multi-Tech, and the Multi-Tech logo are trademarks of Multi-Tech Systems, Inc.
Adobe and Acrobat are trademarks of Adobe Systems Incorporated. Microsoft, Windows, Windows 95, Windows 98,
Windows NT, and Windows 2000 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.
Notice
Though these modems are capable of 56K bps download performance, line impairments, public telephone infrastructure and
other external technological factors currently prevent maximum 56K bps connections.
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, MN 55112
U.S.A
[phone] or [phone]
Fax [phone]
Technical Support [phone]
Internet http://www.multitech.com

Contents
Chapter 1 - Introduction ................................................................................................................................. 4
Product Description ............................................................................................................................................................ 4
Chapter 2 - Hardware Installation .................................................................................................................. 5
We Supply .......................................................................................................................................................................... 5
You Supply ......................................................................................................................................................................... 5
Safety Warnings ................................................................................................................................................................. 5
Connecting the Modem to Your System ............................................................................................................................. 6
Using Your Modem ............................................................................................................................................................. 7
Voice Connections (Voice option only) ............................................................................................................................... 8
Installing the Modem Driver................................................................................................................................................ 9
Removing an Old Modem Driver ........................................................................................................................................ 9
Installing Your Data Communications Software .................................................................................................................. 9
Connecting to the Internet ................................................................................................................................................ 10
Dial-Up Networking .......................................................................................................................................................... 10
Chapter 3 - Operation ................................................................................................................................... 11
About the LED Indicators ................................................................................................................................................. 11
Configuring Your Software ................................................................................................................................................ 12
Configuring Your Modem .................................................................................................................................................. 12
Sending a Fax .................................................................................................................................................................. 13
Chapter 4 - AT Commands, Voice Commands, and Fax Class 1 and 2 Commands ................................ 14
See Commands Reference Guides ................................................................................................................................. 14
Chapter 5 - Troubleshooting ........................................................................................................................ 15
None of the Indicators Light ............................................................................................................................................. 15
The Modem Does Not Respond to Commands ............................................................................................................... 16
The Modem Dials But Cannot Connect ............................................................................................................................ 17
The Modem Disconnects While Online ............................................................................................................................ 18
The Modem Cannot Connect When Answering ............................................................................................................... 18
There Are Garbage Characters on the Monitor ................................................................................................................ 18
The Modem Doesn’t Work with Caller ID ......................................................................................................................... 18
Appendix A - Warranty, Service, and Technical Support ...........................................................................19
Limited Warranty .............................................................................................................................................................. 19
Online Warranty Registration ........................................................................................................................................... 19
Service ............................................................................................................................................................................. 19
International Products ...................................................................................................................................................... 20
Replacement Parts ........................................................................................................................................................... 20
Technical Support ............................................................................................................................................................. 20
Recording Modem Information ......................................................................................................................................... 20
Internet Sites .................................................................................................................................................................... 20
Appendix B - Regulatory Compliance ......................................................................................................... 21
FCC Part 15 ..................................................................................................................................................................... 21
FCC Part 68 Telecom ....................................................................................................................................................... 21
Fax Branding Statement ................................................................................................................................................... 22
Canadian Limitations Notice ............................................................................................................................................. 22
International Modem Restrictions ..................................................................................................................................... 22
EMC, Safety, and R&TTE Directive Compliance .............................................................................................................. 23
New Zealand Telecom Warning Notice ............................................................................................................................ 23
South African Notice ......................................................................................................................................................... 23
Appendix C - Technical Specifications ....................................................................................................... 24
Appendix D - Installing a Modem in Linux .................................................................................................. 26
Standard Linux Serial Port Definitions .............................................................................................................................. 26
Installation ........................................................................................................................................................................ 26
Appendix E - Upgrading the Modem ........................................................................................................... 28
Upgrade Overview ............................................................................................................................................................ 28
Index .............................................................................................................................................................. 30

4
Chapter 1 - Introduction
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
Chapter 1 - Introduction
Congratulations on your purchase of the Multi-Tech MT5656ZDX-Series modem.
•The Multi-Tech MT5656ZDX modem is your data/fax modem.
•The MT5656ZDX-V offers your voice option.
You have acquired one of the finest intelligent data/fax or voice/data/fax modems available today from one of the world’s
oldest modem manufacturers: Multi-Tech Systems, Inc. This user guide will help you install, configure, test, and use your
modem.
Product Description
The Multi-Tech MT5656ZDX and MT5656ZDX-V modems are compatible with the ITU-TV.92 protocol that provide quick
connections, downstream transmissions at speeds up to 56K bps, and upstream transmissions at speeds up to 48K bps
when connected to V.92-compatible Internet Service Providers. The V.92 protocol is able to send downstream from the
Internet to your computer at these speeds because data on the telephone network typically is converted from digitial to
analog only one before it reaches your modem. Upstream transmissions and transmissions between client modems are
limited to 33.6K bps, as are upstream transmissions that are converted more than once on the telephone lines.
Modem features include Plug and Play operation. In standard mode, the modem can store up to four command lines or
telephone numbers of up to 40 characters each in nonvolatile memory. Other modem capabilities include modem-on-hold,
AT&T calling card tone detection, pulse and tone dialing, adaptive answer, V.42bis and V.44 data compression, and self-
resetting lightning protection.
Please note that some V.92 features are turned off in the factory default configuration, and may need to be turned on,
depending on your needs.

5
Chapter 2 - Hardware Installation
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
Chapter 2 - Hardware Installation
This chapter shows you step-by-step how to set up your Multi-Tech modem, test it, and make your first calls.
We Supply
•An MT5656ZDX data/fax modem or a MT5656ZDX-V voice/data/fax modem
•A DC power transformer
•One RJ11 phone cable
•A printed Quick Start Guide
•A CD containing modem drivers, communications software (PhoneTools), this User Guide, AT Commands Reference
Guide which includes voice commands, a Fax 1 Commands Reference Guide, and Adobe Acrobat software
•Four vinyl gripper feet for the bottom of the modem
You Supply
•A computer with an available serial port. The processor speed should be at least 75 MHz in order to take full advantage
of the ZDX-V’s telephony features.
•A shielded RS232 serial cable with a male DB-25 connector on one end and a connector to match your computer’s
serial port on the other end.
•A nearby AC power outlet
•A nearby phone jack
Optional: If you want speakerphone functions along with the ability to record sound or .WAV files through the sound card at
the same time, you will need:
•One stereo PC microphone
•One stereo male to male patch cord
•One sound card
•Speakers
SafetyWarnings
•Use this product only with UL- and CUL-listed computers.
•Never install phone wiring during a lightning storm.
•Never install a phone jack in a wet location unless the jack is specifically designed for wet locations.
•Never touch uninsulated phone wires or terminals unless the phone line has been disconnected at the network
interface.
•Use caution when installing or modifying phone lines.
•Avoid using a phone (other than a cordless type) during an electrical storm; there is a risk of electrical shock from
lightning.
•Do not use a phone in the vicinity of a gas leak.
•To reduce the risk of fire, use only 26 AWG or larger telephone line cord.

6
Chapter 2 - Hardware Installation
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
Connecting the Modem toYour System
Turn off your computer. Placing the modem in a convenient location, connect it to your computer’s serial port, to the phone
line, to AC power, and to your phone.
PWR RS232 PHONE LINE
Figure 2–1. MT5656ZDX Connections.
Connect the Modem to Your PC (RS-232 Connection)
Plug one end of the RS-232 serial cable into the RS-232 connector on the modem, and plug the other end into
a serial port connector on your computer, such as COM1 or COM2. You supply the RS-232 cable.
Connect the Modem to the Phone Jack (Line Connection)
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.
(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
Plug the DC power transformer into an AC power outlet or power strip. Plug the DC power transformer into the
POWER jack on the modem.
Note: Use only the DC power transformer supplied with the modem. Use of any other transformer voids the
warranty and can damage the modem.

7
Chapter 2 - Hardware Installation
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
A Note About Power Connection, Surge Protectors, and Lightning
Power surges and other transient voltages on power lines, such as those caused by lightning strikes, can
damage or destroy your modem. Therefore, we recommend that you plug the modem into a surge protector
rather than directly into a wall outlet, preferably a surge protector that provides protection against electrical
spikes on the phone line as well as on the power line. Note that not even a surge protector can guard against
damage from a nearby lightning strike. During an electrical storm, it is safest to unplug your computer
equipment from both the power outlet and the phone 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 PWR 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.
Note: The Federal Communications Commission (FCC) and Industry Canada impose certain restrictions on
equipment connected to public phone systems. For more information, see Appendix B.
UsingYour Modem
Right now the modem is set up for the most typical user application, that is, the modem is set to make dial-up calls to remote
installations where the calls are answered automatically. Therefore, you shouldn’t need to change the current default
configuration.
You will likely use your data communications software to:
• Launch a data communications session through a set of modem configurations which you select and then
associate with a target phone number. Once you have created, saved, and named this set of information
according to your connection needs and your data communications software’s conventions, the software
then simplifies your dialing. You need not reconfigure the modem nor run the risk of mistakenly keying-in
incorrect information, or
• Enter terminal mode, where you can issue AT commands .

8
Chapter 2 - Hardware Installation
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
Voice Connections (Voice option only)
PWR RS232 PHONE LINE
Figure 2–2. Voice Connections (Optional)
Connect the Microphone
For voice mail or speakerphone applications, plug an unamplified microphone into the MIC jack on the side of
the modem. The microphone should have a stereo 1/8-inch mini plug. Do not use a monophonic microphone.
Connect the Speaker
For speakerphone or voice mail applications, use a 1/8-inch-plug male-to-male stereo patch cord to connect
the SPKR jack on the side of the modem to the LINE IN jack on your sound card. If your sound card does not
have a LINE IN jack, use its MIC jack. The stereo male-to-male patch cord can be purchased at a local PC
retail store.
If you do not have a sound card, you can plug an amplified speaker directly into the SPKR jack.

9
Chapter 2 - Hardware Installation
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
Installing the Modem Driver
If you use Windows 95/98/Me/2000/NT/XP, you must install the modem driver.
If you use another operating system, see Appendix E.
When operating the modem under Windows 95/98/Me/2000/XP, the modem driver can be installed by using the Plug and
Play feature. Follow the 4-step procedure below.
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 User Guide.
2. Insert the MT5656ZDX CD, and then click OK.
3. Windows installs and configures the modem.
4. Click Finish to exit.
For Windows NT, the Install New Modem wizard has one prompt before Step 2. Select Don’t detect my modem; I will
select it from a list, and then click Next. A dialog box with a list of manufacturers and a list of modem models appears.
Then continue with Step 2 above.
Removing an Old Modem Driver
When your new modem replaces another modem, the old modem driver remains in Windows, and the old modem driver
is still selected in HyperTerminal and other Windows applications. Though you can change the application connection
descriptions one at a time, it is easier to force the Windows applications to use the new modem by removing the old modem
driver from Windows.
1. Click the Start button, point to Settings, and click Control Panel.
2. Double-click the Modems icon to open the Modems Properties dialog box.
3. In the list box, select the old modem.
4. Click Remove, and 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.
InstallingYour Data Communications Software
Data communications software is designed to send and receive messages. Multi-Tech includes data communications
software with your modem. However, the modem will work with most data communications software. To install the data
communications software provided with this modem, insert the CD into the CD-ROM drive and click on the Phone Tools
icon. You will be asked to choose your language. The software will automatically load onto your PC.
Note: Data communications software running in a Windows operating system normally do not have to be configured since
they use the Plug and Play configuration supplied by the Windows modem driver. Data communications software running in
DOS or other operating systems may need to be manually configured. See Chapter 3, Operations.

10
Chapter 2 - Hardware Installation
Multi-Tech Systems Inc. MT5656ZDX Series 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 email and newsgroups, your ISP should also provide you with the following in-
formation:
•Email 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 ver-
sion 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 with their service a program that will instruct and configure Dial-Up Networking automatically
for you.

Chapter 3 - Operation
11
Multi-Tech Systems, Inc. MT5656ZDX User Guide
Chapter 3 - Operation
Like any modem, your Multi-Tech modem operates only under the control of a communications program, such as the
communications program included with your modem. It also operates under other general-purpose data communication
programs, such as Windows Terminal and HyperTerminal. For information on how to use the modem with the
communications program of your choice, please refer to the documentation provided with the data communications program.
An experienced modem user can configure the program’s software to change the way the software interacts with a modem
and configure the modem to change the way it operates.
About the LED Indicators
The modem has ten LED indicators on the front panel that indicate status and activity:
Figure 2–1. Front panel
TD
Transmit Data
Flashes when the modem is transmitting data to another modem.
RD
Receive Data
Flashes when the modem is receiving data from another modem.
CD
Carrier Detect
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.
OH
Off-Hook
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
Lights when a communication program is using the modem. It means the modem is ready for an
outgoing or incoming call. It goes off when the communication program disconnects the serial port.
When it goes off, a connected modem will disconnect.
Note: When you turn on the modem, the PWR indicator lights; and if a terminal program is running, the TR
indicator also lights.

Chapter 3 - Operation
12
Multi-Tech Systems, Inc. MT5656ZDX User Guide
ConfiguringYour Software
You may use either the communication program included with your modem or a third-party program. Communication
programs designed for Windows 95 and above normally do not need to be manually configured, since they obtain
configuration information from Windows. Communication programs designed for DOS and other operating systems,
however, may need to be manually configured to work with your modem. Though each communication program is different,
the following procedure should work with most of them.
1. Turn on your computer and run your communications program.
2. Find the dialog box or menu that lets you select your modem. (In Windows Terminal select Settings |
Modem Commands; in HyperTerminal select File | Properties | Phone Number; and in the
communications program select Configure | General Configuration |Communication |Change
Modem.
3. Choose your modem from the program’s modem list. If it isn’t listed, choose a generic modem and modify
the settings as necessary.
4. Change the modem initialization string, if necessary. The factory default configuration works well for most
purposes. To load the factory default configuration, use AT&F. To load a custom configuration that was
saved using the &Wcommand, use ATZ. Note that the Zcommand must be in a command string by itself.
For a Macintosh, the initialization string should include the &D0 command. If you do not want the modem
to always answer the phone, add S0=0 to the string. To use Caller ID with the modem, add S0=2 to the
string (Caller ID information is sent between the first and second rings, so the phone must ring at least
twice before the modem picks up the line). Depending on the software, you might have to end the string
with a carriage return character (^M).
Note: To change the modem’s default configuration, type new commands in the communication pro-
gram’s terminal window, adding the &W command to store them in the modem’s nonvolatile memory. For
instance, to create a default configuration for a Macintosh computer that turns off autoanswer, type
AT&F&D0S0=0&W. The new configuration loads automatically whenever the modem is turned on or
receives the ATZ command.
5. Select the port the modem is connected to (normally COM1 or COM2).
6. Select your serial port speed. This can be labeled “maximum speed,” “DTE bps,” or “baud rate.” Ideally, if
you use data compression, you should set your serial port baud rate to four times the modem’s maximum
transmission speed or faster; however, few files can be compressed enough to require speeds that high,
and not all serial ports can handle speeds that high.
7. If the communication program has an autobaud selection, make sure it is disabled. Autobaud applies only to
older modems, and can cause problems if enabled.
8. If the program allows you to edit the no-connect messages (NO CARRIER, BUSY, NO ANSWER, NO
DIALTONE), make sure there is no space between DIAL and TONE in NO DIALTONE.
9. Refer to the program manual or online help for other configuration choices. In most cases you can accept
the default values.
ConfiguringYour Modem
Your modem normally is configured through Windows or through the communication program you are using. The default
settings work best for most purposes. However, you also can configure your modem by sending AT commands to the
modem. See the AT Command Reference Guide for a list of AT (data) commands and how to use them.

Chapter 3 - Operation
13
Multi-Tech Systems, Inc. MT5656ZDX User Guide
Sending a Fax
With your data communications software, you can use your modem to send and receive faxes directly from your computer.
The following steps show you how to fax a document directly from a Windows application without opening the data communi-
cations program.
1. Create a document in a Windows application, such as Word, a graphics editor, or a spreadsheet. Keep
the application and the document open, and select Print from the File menu.
2. Select CAPTURE FAX BVRP as the printer driver, and then click OK. The Send Fax wizard appears.
3. In the Recipient section, type the required information or extract it from the Phone Book by clicking
this icon.
4. In the Template section, optionally select a cover page and type a cover message.
5. Select the document to be sent. The default file when sending from within a Windows application is
Capture.dgr.
6. Select the date and time to send the document, if you do not want to send it immediately.
7. Click Finish to start the transmission.

14
Chapter 4 - AT Commands and Fax Class 1 Commands
Multi-Tech Systems, Inc. MT5656ZDX User Guide
Chapter 4 - AT Commands,Voice
Commands, and Fax Class 1 and 2
Commands
See Commands Reference Guides
AT Commands and Voice Commands are in the AT Command Reference Guide.
Fax Class 1 Commands and Fax Class 2 Commands are documented in separate Fax Reference Guides.
All Reference Guides are included on the MT5656ZDX CD and on the Multi-Tech Web site.

15
Chapter 5 - Troubleshooting
Multi-Tech Systems, Inc. MT5656ZDX User Guide
Chapter 5 -Troubleshooting
Your modem was thoroughly tested at the factory before it was shipped. If you are unable to make a successful connection,
or if you experience data loss or garbled characters during your connection, check the list of troubleshooting procedures
before calling Multi-Tech.
•None of the LEDs light when the modem is on.
•The modem does not respond to commands.
•The modem dials but is unable to make a connection.
•The modem disconnects while online.
•The modem cannot connect when answering.
•File transfer is slower than it should be.
•Data is being lost.
•There are garbage characters on the monitor.
•The modem doesn’t work with Caller ID.
•Fax and data software can’t run at the same time.
If you experience problems, please check the following possibilities before calling Technical Support (refer to
Appendix A).
None of the Indicators Light
When you turn on the modem, the PWR indicator and the terminal turn on. If the LEDs remain off, the modem is probably not
receiving power.
✔✔
✔✔
✔Make sure the modem’s power switch is on, especially if you normally turn the modem on by turning on a
power strip.
✔✔
✔✔
✔If the modem is plugged into a power strip, make sure the power strip is plugged in and its power switch is
on.
✔✔
✔✔
✔Make sure the transformer module is firmly connected to the modem and to the wall outlet or power strip.
✔✔
✔✔
✔If the power strip is on and the modem switch is on, try moving the transformer module to another outlet on
the power strip.
✔✔
✔✔
✔Test that the outlet is live by plugging another device, such as a lamp, into it.
✔✔
✔✔
✔The modem or the DC power transformer may be defective. If you have another Multi-Tech modem, try
swapping modems. If the problem goes away, the first modem or the DC power transformer may be defec-
tive. Call Technical Support for assistance.
CAUTION: Do not under any circumstances replace the transformer module with one designed for another
product; doing so can damage the modem and void your warranty.

16
Chapter 5 - Troubleshooting
Multi-Tech Systems, Inc. MT5656ZDX User Guide
The Modem Does Not Respond to Commands
✔✔
✔✔
✔Make sure the modem is plugged in and turned on. (See “None of the Indicators Light.”)
✔✔
✔✔
✔Make sure you are issuing the modem commands from the data communications program, either manually
in terminal mode or automatically by configuring the software. (You cannot send commands to the modem
from the DOS prompt.)
✔✔
✔✔
✔Make sure you are in terminal mode in your data communications program, then type AT and press ENTER.
If you get an OK response from your modem, your connections are good and the problem likely is in the
connection setup in your communications program.
✔✔
✔✔
✔If you don’t get an OK, the problem may still be in the communications program. Make sure you have done
whatever is necessary in your software to make a port connection. Not all communication programs con-
nect to the COM port automatically. Some connect when the software loads and remain connected until
the program terminates. Others can disconnect without exiting the program. The modem’s TR indicator
lights to show that the software has taken control of the modem through the COM port.
✔✔
✔✔
✔Your communications program settings may not match the physical port the modem is connected to. The
serial cable might be plugged into the wrong connector—check your computer documentation to make
sure. Or you might have selected a COM port in your software other than the one the modem is physically
connected to—compare the settings in your software to the physical connection.
✔✔
✔✔
✔If the modem is on, the cable is plugged into the correct port, the communications program is configured
correctly, and you still don’t get an OK, the fault might be in the serial cable. Make sure it is firmly connect-
ed at both ends.
✔✔
✔✔
✔Is this the first time you have used the cable? If so, it may not be wired correctly. Check the cable descrip-
tion on the packaging to make sure the cable is the right one for your computer.
✔✔
✔✔
✔Peripheral expansion cards, such as sound and game cards, might include a serial port preconfigured as
COM1 or COM2. The extra serial port, or the card itself, may use the same COM port, memory address, or
interrupt request (IRQ) as your communication port. Be sure to disable any unused ports.
Windows 9x and 2000: Right-click on My Computer, select Properties from the menu, click on the De-
vice Manager tab, double-click on Ports, then double-click on the communication port your modem is
connected to. In the port’s Properties sheet, click on the Resources tab to see the port’s input/output
range and interrupt request. If another device is using the same address range or IRQ, it appears in the
Conflicting Device List. Uncheck Use automatic settings to change the port’s settings so they do not
conflict with the other device, or select the port the conflicting device is on and change it instead. If you
need to open your computer to change switches or jumpers on the conflicting device; refer to the device’s
documentation.
Windows NT 4.0: To look for address or IRQ conflicts, click Start, Programs, Administrative Tools (Com-
mon), and Windows NT Diagnostics. In the Windows NT Diagnostics dialog box, click the Resources
tab to see which input/output ranges and interrupt requests are in use. If you need to open your computer
to change switches or jumpers on the conflicting device; refer to the device’s documentation.
✔✔
✔✔
✔The serial port might be defective. If you have another serial port, install the modem on it, change the COM
port setting in your software, and try again.
✔✔
✔✔
✔The modem may be defective. If you have another Multi-Tech modem, try swapping modems. If the prob-
lem goes away, the first modem may be defective. Call Technical Support for assistance (Refer to
Appendix A).

17
Chapter 5 - Troubleshooting
Multi-Tech Systems, Inc. MT5656ZDX User Guide
The Modem Dials But Cannot Connect
There can be several reasons the modem fails to make a connection. Possibilities include:
•lack of a physical connection to the telephone line.
•a missing dial tone.
•a busy signal.
•a wrong number.
•no modem at the other end.
•a faulty modem, computer, or software at the other end.
•incompatibility between modems.
You can narrow the list of possibilities by using extended result codes. Extended result codes are enabled by default. If they
have been disabled, include V1X4 in the modem’s initialization string, or in terminal mode enter ATV1X4 and press ENTER.
When you dial again, the modem reports the call’s progress.
✔If the modem reports NO DIALTONE, check that the modem’s phone line cable is connected to both the
modem’s LINE jack (not the PHONE jack) and the phone wall jack. If the cable looks secure, try replacing
it. If that doesn’t work, the problem might be in your building’s phone installation. To test the building
installation, plug a phone into your modem’s phone wall jack and listen for a dial tone. If you hear a dial
tone, your modem might be installed behind a corporate phone system (PBX) with an internal dial tone that
sounds different from the normal dial tone. In that case, the modem might not recognize the dial tone and
might treat it as an error. Check your PBX manual to see if you can change the internal dial tone; if you
can’t, change your modem’s initialization string to replace X4 with X3, which will cause the modem to
ignore dial tones (note, however, that X3 is not allowed in some countries, such as France and Spain).
✔✔
✔✔
✔If the modem reports BUSY, the other number might be busy, in which case you should try again later, or it
might indicate that you have failed to add a 9, prefix to the phone number if you must dial 9 for an outside
line.
If you must dial 9 to get an outside line, the easiest way to dial it automatically is to include it in the
modem’s dial prefix, e.g., ATDT9,. Note the comma, which inserts a pause before the number is dialed. By
inserting 9, into the dial prefix, you do not have to include it in each directory entry.
To change the dial prefix in Windows 95 HyperTerminal, select Connect from the Call menu, click Dialing
Properties, and type 9 in the local and long distance boxes in How I dial from this location.
✔✔
✔✔
✔If the modem reports NO ANSWER, the other system has failed to go off-hook, or you might have dialed a
wrong number. Check the number.
✔✔
✔✔
✔If the modem reports NO CARRIER, the phone was answered at the other end, but no connection was
made. You might have dialed a wrong number, and a person answeredinstead of a computer, or you might
have dialed the correct number but the other computer or software was turned off or faulty. Check the
number and try again, or try calling another system to make sure your modem is working. Also, try calling
the number on your telephone. If you hear harsh sounds, then another modem is answering the call, and
the modems might be having problems negotiating because of modem incompatibilities or line noise. Try
connecting at a lower speed.

18
Chapter 5 - Troubleshooting
Multi-Tech Systems, Inc. MT5656ZDX User Guide
The Modem DisconnectsWhile Online
✔✔
✔✔
✔If you have Call Waiting on the same phone line as your modem, it can interrupt your connection when
someone tries to call you. If you have Call Waiting, disable it before each call. In most phone areas in
North America, you can disable Call Waiting by preceding the phone number with *70 (check with your
local phone company).
You can automatically disable Call Waiting by including the disabling code in the modem’s dial prefix (e.g.,
ATDT*70,—note the comma, which inserts a pause before the number is dialed). To change the dial prefix
in Windows Terminal, select Settings | Modem Commands. To change it in HyperTerminal, select
Connect from the Call menu, click Dialing Properties, check This location has Call Waiting, and select
the correct code for your phone service.
✔✔
✔✔
✔If you have extension phones on the same line as your modem, you or someone else can interrupt the
connection by picking up another phone. If this is a frequent problem, disconnect the extension phones
before using the modem, or install another phone line especially for the modem.
✔✔
✔✔
✔Check for loose connections between the modem and the computer, the phone jack, and AC power.
✔✔
✔✔
✔You might have had a poor connection because of line conditions or the problem might have originated on
the other end of the line. Try again.
✔✔
✔✔
✔If you were online, it might have hung up on you because of lack of activity on your part or because you
exceeded your time limit for the day. Try again.
The Modem Cannot ConnectWhen Answering
✔✔
✔✔
✔Autoanswer might be disabled. Turn on autoanswer in your data communications program or send the
command ATS0=1 (ATS0=2 if you have Caller ID service) to your modem in terminal mode.
There Are Garbage Characters on the Monitor
✔✔
✔✔
✔Your computer and the remote computer might be set to different word lengths, stop bits, or parities. If you
have connected at 8-N-1, try changing to 7-E-1, or vice-versa, using your communications program.
✔✔
✔✔
✔You might be experiencing line noise. Enable error correction, if it is disabled, or hang up and call again;
you might get a better connection the second time.
✔✔
✔✔
✔Try entering the &V1 command to display information about the last connection, making a screen print of
the connection statistics, and checking for parameters that might be unacceptable.
The Modem Doesn’tWork with Caller ID
✔✔
✔✔
✔Caller ID information is transmitted between the first and second rings, if the modem is set to answer
after only one ring (S0=1), the modem will not receive Caller ID information. Check your initialization string,
and if necessary change it to set the modem to answer after the second ring (S0=2).
✔✔
✔✔
✔Make sure that you have Caller ID service from your telephone company.

Appendix A - Warranty and Technical Support
19
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
Appendix A -Warranty, Service, and
Technical Support
LimitedWarranty
Multi-Tech Systems, Inc. (MTS) warrants that this product will be free from defects in material or workmanship for a period of
ten years from the date of purchase or, if date of purchase is not provided, ten years from the date of shipment.
MTS MAKES NO OTHER WARRANTY, EXPRESSED OR IMPLIED, AND ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED.
This warranty does not apply to any products that have been damaged by lightning storms, water, or power surges, or that
have been neglected, altered, abused, used for a purpose other than the one for which they were manufactured, repaired by
the customer or any party without MTS’s written authorization, or used in any manner inconsistent with MTS’s instructions.
MTS’s entire obligation under this warranty shall be limited (at MTS’s option) to repair or replacement of any products that prove
to be defective within the warranty period, or, at MTS’s option, issuance of a refund of the purchase price. Defective
products must be returned by Customer to MTS’s factory with transportation prepaid.
MTS WILL NOT BE LIABLE FOR CONSEQUENTIAL DAMAGES AND UNDER NO CIRCUMSTANCES WILL ITS LIABILITY
EXCEED THE PURCHASE PRICE FOR DEFECTIVE PRODUCTS.
OnlineWarranty Registration
If you have access to the World Wide Web, you can register your Multi-Tech product online at the following URL:
http://www.multitech.com/TOOLS/FORMS/register/warranty.asp
Service
North American Products
In the event that service is required, products may be shipped, freight prepaid, to our Mounds View, Minnesota, factory.
Please send modems that require repairs to the following address:
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, MN 55112
U.S.A.
Attn: Repairs, Serial #______
A Returned Materials Authorization (RMA) is not required. Return shipping charges (surface) will be paid by MTS. Please
include inside the shipping box a description of the problem, a return shipping address (must have street address, not P.O.
Box), a telephone number, and if the product is out of warranty, a check or purchase order for repair charges.
Extended two-year overnight replacement agreements are available for selected products. Please refer to our Overnight
Replacement Agreement at http://www.multitech.com/PARTNERS/Programs/orc/DEFAULT.asp for details on rates and
coverages. Please direct your questions regarding technical matters, product configuration, verification that the product is
defective, etc., to our Technical Support department at 800 972-2439.
Please direct your questions regarding repair expediting, receiving, shipping, billing, etc., to our Repair Accounting
department at 800 328-9717 or 763 785-3500.
Repairs for damages caused by lightning storms, water, power surges, incorrect installation, physical abuse, or user-caused
damages are billed on a time-plus-materials basis.

Appendix A - Warranty and Technical Support
20
Multi-Tech Systems Inc. MT5656ZDX Series User Guide
International Products
Your distributor should contact Amex, Inc., for information about repairs for your Multi-Tech product:
Amex, Inc.
2724 Summer Street NE
Minneapolis, MN 55413
U.S.A.
Tel: [phone]
Fax: [phone]
Please direct questions regarding technical matters, product configuration, verification that the product is defective, etc., to
our Technical Support department nearest you (see Technical Support below), When calling the U.S., please direct
questions regarding repair expediting, receiving, shipping, billing, etc., to our Repair Accounting department at 763 785-
3500.
Repairs for damages caused by lightning storms, water, power surges, incorrect installation, physical abuse, or user-
caused damages are billed on a time-plus-materials basis.
Replacement Parts
SupplyNet, Inc. can supply you with replacement power supplies, cables, and connectors for select Multi-Tech products. You
can place an order with SupplyNet via mail, phone, fax, or the Internet at the following addresses:
Mail: SupplyNet, Inc.
613 Corporate Way
Valley Cottage, NY 10989
Phone: [phone]
Fax: [phone]
Email: [email protected]
Internet: http://www.thesupplynet.com
Technical Support
Multi-Tech Systems has an excellent staff of technical support personnel available to help you get the most out of your Multi-
Tech product. If you have any questions about the operation of this unit, please call 800 972-2439 (USA and Canada) or 763
785-3500 (international and local). Please have modem information available. You can also contact Technical Support by
email at the following addresses:
U.S., Canada, and Europe: [email protected]
France: [email protected]
India: [email protected]
U.K.: [email protected]
Recording Modem Information
Complete the following information about your Multi-Tech modem before calling Technical Support.
Modem Model No.:___________________
Modem Serial No.:____________________
The model and serial numbers are printed on the bottom of the modem.
Note the status of the modem before calling Technical Support. The status includes information about LED indicators,
screen messages, diagnostic test results, problems with a specific application, etc.
Internet Sites
Multi-Tech has a Web site at:
http://www.multitech.com
and an ftp site at:
ftp://ftp.multitech.com