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Chapter 5 - Troubleshooting
The Modem Dials But Cannot Connect
There can be several reasons the ZBA fails to make a connection. Possibilities include
• lack of a physical connection to the telephone line.
• incompatibility between modems.
• a busy signal.
• a wrong number.
• no modem at the other end.
• a faulty modem, computer, or software at the other end.
You can narrow the list of possibilities by using extended result codes. Extended result codes are
enabled by default. If they have been disabled, enter ATV1X4 and press ENTER while in terminal
mode, or include V1X4 in the modem’s initialization string. When you dial again, the modem will report
the call’s progress.
• If the modem reports NO DIALTONE , check that the modem’s telephone line cable is
connected to both the modem’s LINE jack (not the PHONE jack) and the telephone wall jack.
If the cable looks secure, try replacing it. If that doesn’t work, the problem might be in your
building’s telephone installation. To test the building installation, plug a telephone into your
modem’s telephone wall jack and listen for a dial tone. If you hear a dial tone, your modem
might be installed behind a company 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 98 HyperTerminal, select
Call 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 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.