[SIPForum-discussion] 183 Session Progress with SDP missing info

[Andrey Ermoshin]

Hi, I think that one reason could be that there is no any valid codec
offer in 183 message (18 101 payloads exists, but no g729 offer in
SDP).

2012/6/8 Munjal Patel <munjal84 at gmail.com>:
> hi everyone i'm new to SIP and needing some help with a issue i'm having,
> any help would be appreciated
>
> A= Cisco 2811 UAC
> B= Carrier end point
>
> During call setup carrier is responding back with 183 Session Progress SDP
> but with missing “a”-Line, here is the snips from the PCAP:
>
>
> Invite- A to B (SIP/SDP)
>
> SDP>
> (M): audio 47640 RTP/AVP 18 101
> (A): rtpmap:18 g729/8000/1
> (A): rtpmap:101 telephone-event/8000/1
> (A): ptime:20
>
> 100 Trying- B to A (SIP)
>
> 183 Session Progress- B to A (SIP/SDP)
>
> SDP>
> (M): audio 60050 RTP/AVP 18 101
> (A): rtpmap:101 telephone-event/8000/1
> (A): ptime:20
>
> Cancel- A to B (SIP)
>
>
> My question, is it normal for Cisco 2811 to send a cancel or can it be
> configured to try to renegotiate media with the carrier.
>
>
> Thank You,
>
> Munjal Patel
>
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