[Freeswitch-users] DynamicRTP-Type-98

[Troy Anderson]

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 at 32000h,G7221 at 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

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