Multi-Tech Systems MT5634IND - Manual (Page 21)

Chapter 6 – Troubleshooting
Multi-Tech Systems, Inc. MT5634IND User Guide (S000369A) 21
• If there is no answer on the remote end, the modem reports NO CARRIER. 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.
Modem Cannot Connect When Answering
• 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.
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 insure
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 in online mode 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.