3Com OfficeConnect 3CXSH654B User Manual page 43

Symptom
Modem clicks repeatedly, but no
connection is made
Solution
You are trying to connect to a digital phone system or a PBX. Change lines to
connect to a standard analog telephone line. Ordinarily, you would get a DIGITAL
LINE ERROR message, but if the current is under 100mA, the modem will click
repeatedly but the message will not appear.
The cable may not be seated securely. Check both cable connections to the modem
and to the phone jack or cellular phone.
Tip and Ring may be reversed. Try another telephone port.
Modem Troubleshooting 37