[SIPForum-discussion] Media Port change in SDP

[ashish rawat]

Hi Amit,

I think far end (UAS) should accept this media change in the Re-Invite till the time UAC is incrementing the version number in the "0" field of  the sdp of the Re-Invite by one. If the version is not incrementing then it is upto the UAS implementation to accept the new SDP or ignore it.


Please see snippet from sdp and sip rfcs' http://www.ietf.org/rfc/rfc3264.txt When issuing an offer that modifies the session, the "o=" line of the new SDP MUST be identical to that in the previous SDP, except that the version in the origin field MUST increment by one from the previous SDP.  If the version in the origin line does not increment, the SDP MUST be identical to the SDP with that version number. 

Thanks,
Ashish Rawat



________________________________
 From: "Banda, Srinivas (Srinivas)" <sribanda at avaya.com>
To: Amit Salunkhe <amitsalunkhe21 at gmail.com> 
Cc: "discussion at sipforum.org" <discussion at sipforum.org> 
Sent: Saturday, 27 July 2013 10:52 PM
Subject: Re: [SIPForum-discussion] Media Port change in SDP
 

Hi Amit, 

Re-Invite is used to change/ modify the session parameters. So in this case use A switching from Audio call to Audio+Video call, so it is ok change the RTP port of Audio. 

Regards
Srinivas


On 27-Jul-2013, at 8:42 PM, "Amit Salunkhe" <amitsalunkhe21 at gmail.com> wrote:

> Hi All,
> 
> Call scenario is
> 
> 1. A Calls B (Audio Call)
> 2. Call got connected
> 3. Now A want to switch that call to Video hence A User end device send Re-INVITE with Audio + video SDP
> 4. Call got connected as B Party accept that Video Call offer.
> 
> Now the change we found in SDP Audio part is- Initial Audio call A offer Audio/Media port as 1001 but while offering Video call with Re-invite A party end device change Audio Port to 2000.
> 
> My question is this correct behavior? is there any RFC/Standard docs describe this valid or invalid to change media port for call type change in same session.
> 
> Also whether B party or media anchoring device(SBC/Softswitch) need to accept this change?
> 
> 
> Amit- 
>  
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