[asterisk-dev] why 4 UDP ports per SIP call?

[Johansson Olle E]

22 nov 2007 kl. 10.29 skrev Klaus Darilion:

>
>
> Olle E Johansson wrote:
>> 19 nov 2007 kl. 20.53 skrev Klaus Darilion:
>>
>>> Hi!
>>>
>>> Analyzing Asterisk I see 4 new UPD sockets opened by Asterisk per
>>> incoming SIP call. I would assume RTP+RTCP=2, but why are there 4
>>> ports
>>> opened?
>> Have you enabled video at all?
>
> I have video enabled in Asterisk, but the INVITE sent to Asterisk  
> had no
> video description in the SDP. Will Asterisk open the video RTP ports
> also if the incoming INVITE does not offer video?

Well, *embarrassing smile*, yes. Hrrm.

Due to the interesting architecture of the SIP channel, we open all  
those ports
for every call, but should close them after the initial INVITE/200 OK/ 
ACK if I
remember correctly, or sooner if the actual device doesn't support  
video.

/O