Race condition in hold/resume

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What steps will reproduce the problem?
1.Webrtc users B1,B2(browsers) 
2.B1 is in office network and B2 connected though VPN 
3.B1 makes video call to B2 
4.After the call is established successfully 
B1 and B2 pressing the hold button simultaneously 
B2 is recieving 491 Another INVITE in progress and getting the message failed 
on hold 
5.From the originating side it is sending the INVITE with sendonly .B2 is 
giving the 200 OK response with recv only 
6.When again the Originator is sending the INVITE for resume B2 is sending the 
200 OK with recv only parameter in the SDP instead of send-recv 

What is the expected output? What do you see instead?
B2 should send in the 200 OK with send-recv in sdp. 

How can we avoid this race condition for hold/resume.

Original issue reported on code.google.com by chaudhar...@gmail.com on 28 Oct 2014 at 11:46

jacknab / sipml5

Race condition in hold/resume #193