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

[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?

regards
klaus