Monday, December 29, 2008

Modem Error: NO CARRIER

What to check when you get "NO CARRIER" (numeric code: 3) error from Modem:
  • Verify Modem is connected to phone line properly;
  • Verify the phone number you are dialing works properly by calling this number using your phone, and verify that you hear: first ring tone, then the negotiation tone (yes, you should be able to hear the chirping sound over a regular phone);
If you can hear the negotiation tone, but frequently get "NO CARRIER" error, here is a solution:
Set modem register S7 to a longer timeout value. 50 is the default, you can set it to 120 (ATS7=120). Sometimes, you can set this timeout value through MODEM configuration GUI, you can find something like: "Cancel the call if not connected within __ seconds".