[SIPForum-discussion] Change the Payload in the SDP from dynamic to standard

[Murali Natesh]

Hello Amiga,

Kindly ask carrier to send correct payload type 18 for G.729 and Telephone
events 101.

The payload type for G.729 is 18 and for telephone events they can send 101
which is mostly used for DTMF or dynamic value 96-127 if your gateway
properly negotiate these values.

The reason for audio may be carrier is sending audio via PT 101 instead of
sending via PT 18.Wireshark trace will help you to identify whether
renegotiation has been accepted at UAS end or not.

Regards,
Murali
On 21 Aug 2015 11:33 pm, "Moy Amiga" <moises.amiga at c3ntro.com> wrote:

> Hi all
>>
>> We have an issue with the payload for the G.729
>>
>> My carrier send us the call with the payload 101 for G.729 in the SDP
>> like this:
>>
>> v=0
>> o=Sonus_UAC 5078 10327 IN IP4 192.168.1.0
>> s=SIP Media Capabilities
>> c=IN IP4 192.168.1.1
>> t=0 0
>> m=audio 10198 RTP/AVP 101 8 0
>> a=rtpmap:101 G729/8000
>> a=fmtp:101 annexb=no
>> a=rtpmap:8 PCMA/8000
>> a=rtpmap:0 PCMU/8000
>> a=sendrecv
>> a=maxptime:20
>>
>> and the call complete correctly.
>>
>> but when the UAC need to transfer this call,
>> ​the UAC
>>  changes the payload to 18 for G729 (and add the DTMF), like this:
>>
>> v=0
>> o=BroadWorks 74714131 4 IN IP4 192.168.2.0
>> s=-
>> c=IN IP4 192.168.2.1
>> t=0 0
>> m=audio 26384 RTP/AVP 18 8 0 101
>> a=rtpmap:18 G729/8000
>> a=rtpmap:8 PCMA/8000
>> a=rtpmap:0 PCMU/8000a=rtpmap:101 telephone-event/8000
>> a=fmtp:101 0-15
>> a=ptime:20
>>
>>
>> *And after this change i don't have audio.*
>>
>> what is the right thing to do in this case?
>>
>>
>> P.S.
>> I see the RTP for the carrier in the wireshark like UNKNOWN...
>>
>> [image: Imagen integrada 1]
>>
>> Best regards
>>
>>
>> --
>>
>> *Moisés Amiga*
>>
>> *SBC Operation*
>>
>>
>>
>
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