occasional 1-way audio problems with 3.3 and h.323

[joshw]

We are running CCM 3.3 and an IOS h323 gateway with 12.2.15T and we occasionally are having problems with 1-way audio on the outbound PRI calls. The IP phone will show call proceed and the user will hear no ringback until the caller picks up. Then the caller will not be able to hear the person on the IP phone but the IP phone will hear the caller. This is only happening with certain numbers on the PSTN. Any ideas?

[jasyoung]

This can be a bug, or can be a problem with answer supervision. Try some of the following URLs:

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a008009484b.shtml

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a0080111b58.shtml

I have had to use the "voice rtp send-recv" command before to force the audio path to be opened. There are other fixes you can try as well.

There is a bug in 12.2(15)T1 that causes one-way audio if you send any DTMF digits from the phone after the call is established. I don't have the bug ID handy. It is not present in 12.2(15)T, nor is it present in 12.2(15)T2. You mention you're running 12.2(15)T, but make sure it's not in fact 12.2(15)T1.