Outgoing POTS calls fail, dropped digits

Asterisk is working great; when it’s going right.

Six out of ten outgoing calls fail to dial properly.

Specs: Digium Wildcard 810p w/ echo cancelation, Asterisk v1.8.11, Polycom IP450, 8 POTS lines

All internal calls work great.
All incoming calls work great.
Only 40% of outgoing calls work.

60% of the time we get error messages from the phone company indicating the dialed number is incomplete. It’s as if a digit is being dropped or otherwise ignored by AT&T (our carrier).

All logging and debugging from Asterisk indicates the proper phone number is being dialed. The outgoing numbers appear properly and pass our dialplans. I captured DAHDI audio into a WAV file. I analyzed it with Audacity and indeed the correct number of digits are being dialed … followed by another digit tone about 1.5 seconds later.


  • What would cause AT&T to ignore a dialed digit?

  • What is that extra digit tone sent about 1.5 seconds after the outgoing number is dialed?

Being an intermittent error this is driving me crazy. Especially since this new phone system was supposed to be humming along this morning. Apparently the system is playing an April fools joke on me.

You help is appreciated!