[SIPForum-discussion] Media Port change in SDP

Steve Underwood steveu at coppice.org
Mon Aug 5 03:50:48 UTC 2013

On 07/27/2013 12:48 PM, Amit Salunkhe 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-
Others have commented that this is compliant behaviour, but more 
importantly, from a practical point of view, it is common practice. Many 
systems handle voice on some boxes, video on others, FAX on a third 
group, etc. So, its something you will often see in the real world, and 
you must handle correctly.


More information about the discussion mailing list