I noticed a problem with calls originating from the mod_callcenter. The order of the codecs in the Media Description portion of the SDP is different for calls from mod_callcenter than when dialing the extension from another extension. Specifically, ITU-T G.711 PCMU is coming first on calls that work, and DynamicRTP-Type-98 is coming first on those that don't. A Polycom 450 is returning a 488 Not Acceptable Here message on the callcenter calls, and an Aastra 6731i has extremely choppy audio. If I tell the Aastra to only allow G722, all works as expected.

I have my codecs set up in FS as global_codec_prefs=G7221@32000h,G7221@16000h,G722,PCMU,PCMA,GSM

Can anyone explain what DynamicRTP-Type-98 is and why it would be in the SDP when I'm not specifying it in the codec list?

Here's what the Media Description portion looks like when calling extension to extension:

Media Description, name and address (m): audio 10140 RTP/AVP 0 98 99 9 8 3 101 13

Media Type: audio

Media Port: 10140

Media Protocol: RTP/AVP

Media Format: ITU-T G.711 PCMU

Media Format: DynamicRTP-Type-98

Media Format: DynamicRTP-Type-99

Media Format: ITU-T G.722

Media Format: ITU-T G.711 PCMA

Media Format: GSM 06.10

Media Format: DynamicRTP-Type-101

Media Format: Comfort noise

Here's what the Media Description portion looks like when mod_callcenter initiates the call:

Media Description, name and address (m): audio 12606 RTP/AVP 98 99 9 0 8 3 101 13

Media Type: audio

Media Port: 12606

Media Protocol: RTP/AVP

Media Format: DynamicRTP-Type-98

Media Format: DynamicRTP-Type-99

Media Format: ITU-T G.722

Media Format: ITU-T G.711 PCMU

Media Format: ITU-T G.711 PCMA

Media Format: GSM 06.10

Media Format: DynamicRTP-Type-101

Media Format: Comfort noise

Thanks!

-Troy