Chapter 7 – Troubleshooting
Multi-Tech Systems, Inc. MT5634ZBA-Series User Guide (S000286G) 26
• 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 answered instead 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.
• Poor line conditions can affect the connection. When using V.34 or V.32 client-to-client connections in poor
conditions, setting S38=0 may result in better performance.
The Modem Disconnects While Online • If you are not using Modem on Hold, Call Waiting can interrupt your connection when someone tries to call you.
If you have Call Waiting service, disable it before each call. In most telephone areas in North America, you can
disable Call Waiting by preceding the telephone number with *70 (but first check with your local telephone
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 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 telephone 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.
• Your ISP 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 default DTR Control command (&D2) inhibits autoanswer. To enable autoanswer, change DTR Control to
&D0, and make sure &Q0, &Q5, or &Q6 is also set. For more information, see the &D command in the AT
Commands Reference Guide. For information on changing the modem’s default configuration, see “Install and
Configure Your Software” in Chapter 2.
• Autoanswer might be disabled. Turn on autoanswer in your communications program or send the command
ATS0=1 (ATS0=2 if you have Caller ID service) to your modem in terminal mode.
• Telephone line is not functional or is connected to PHONE jack and should be connected to the LINE jack.
File Transfer Is Slower Than It Should Be • If you are using a slow transfer protocol, such as Xmodem, try Zmodem or Ymodem/G instead.
• Is your line noisy? If there is static on your line, the modem has to resend many blocks of data to ensure
accuracy. You must have a clean line for maximum speed.
• Are you downloading a compressed file with MNP 5 hardware compression enabled? Since hardware data
compression cannot compress a file already compressed by an archiving program, the transfer can be
marginally slower with data compression enabled than with it disabled.
• Does your Internet service provider (ISP) use the same 56K protocol as your modem? The default setting of
your modem is to connect using either the V.92 or the V.90 protocol, depending on which one the ISP’s modem
is using. If your ISP uses the V.90 protocol, the maximum speed you will be able to upload at is 33,600 bps.
Check with your ISP to see which protocols it supports.
• Are you trying to send a file to another client modem? If so, then your maximum possible connect speed is
33,600 bps. You can upload at speeds up to 48,000 bps only when connected to an ISP that supports the V.92
protocol.
• Try entering the I11 command or the &V command in command mode to display information about the last
connection, making a screen print of the connection statistics, and checking for parameters that might be
unacceptable.