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

[Yasin Tahir]

>  

You Carrier is using payload type 100 that only handle 0-15 type DTMF and you are using 18 . You need to tell you carrier to send you payload type 18.Look at RFC 4733

**********************RFC
>  For example, if the payload format uses the payload type number 100,
>    and the implementation can handle the DTMF tones (events 0 through
>    15) and the dial and ringing tones (assuming as an example that these
>    were defined as events with codes 66 and 70, respectively), it would
>    include the following description in its SDP message:
> 
>       m=audio 12346 RTP/AVP 100
>       a=rtpmap:100 telephone-event/8000 

************************



>       a=fmtp:100 0-15,66,70On Aug 21, 2015, at 9:04 AM, 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/8000
> a=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.png>
> 
> Best regards
> 
> 
> -- 
> Moisés Amiga
> 
> SBC Operation
> 
> 
> 
> 
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