3Com 980/000048/001 manual Modem Telephone Line Connection

Troubleshooting Guide 3-3

Modem - Telephone Line Connection

Connection Problems in Answering a Call

Modem does not receive a dial tone

Attach a telephone direct to the wall outlet to check if a dial tone exists.

Make sure the telephone line is connected to the appropriate modem’s rear panel PSTN jack.

Modem does not go off-hook and answer an incoming call

Check that the auto-answer ring count configuration option (S-Register 0) is set to a value other than 0.

Check that the DTE is providing DTR to the modem.

If the DTE does not provide DTR to the modem, check that the modem’s DTR signalling configuration option is set to ignore the state of DTR.

Check that all cables are attached to the right connectors at the rear of the modem.

Modem goes off-hook, answers, but does not connect

Perform a local analogue loop test and check that data entered at the DTE is echoed back to the DTE.

Check that the originating modem’s configuration is compatible with your receiving modem’s configuration.

Check that the originating modem recognizes your modem’s answer tone.

Check that the originating modem supports your modem’s operating protocols.

Force your modem to operate using the same transmission protocol as the originating modem to see if they connect.