[SIPForum-discussion] Codec Prefrence Option

[Shakil, Rashid]

I came across to this situation where we receive inbound call the codec
preference set on the SIP INVITE is 711 first and 729 second (m=audio
50000 RTP/AVP 0 18 100) when our softswitch reply back with a 200 OK
with SDP we set the preference as 729 first and 711 second (m=audio 3006
RTP/AVP 18 0 100). Instead of cutting the media over to 729 (means
select this as a codec because the 200 OK has 729 set as preference and
initial INVITE has both options) The peering partner sends a RE-INVITE
with 729 as the only option (a=rtpmap:18 G729/8000).

 

My question is this legal in SIP. Is codec can be negotiated that way as
well. I thought that carrier should negotiate the codec base on the
preference my Softswitch set on 200 OK

 

 

 

 

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