[reSIProcate] 3PCC (Third Party Call Controll) support?

[Ilia Krustev]

Hi guys,

I'm trying to use resip::dum (resiprocate-0.9.0-5019) to initiate a call 
while being a third party in the call.
I need to INVITE party A with no initial SDP (no contents). In this case 
the offer is expected to come from the called party - in the 200 OK, or 
earlier.
I then use this offer to INVITE party B. Finally I send the party B 
answer to party A in my ACK.

I'm wondering is this supported at all.

I tried several things to provide to 
DialogUsageManager::makeInviteSession(...) as initial SDP offer:

1. Passing null SdpContents* pointer leads to segfault.
ClientInviteSession calls InviteSession::makeSdp(*initialOffer) and 
tries to copy it.

2. Passing pointer to the SdpContents::Empty - does not crash, but does 
not work either.
I need no body to be sent, but ill formed SDP content is sent instead.

3. Passing Data("") to a SdpContent instance makes it crash when later 
attempts to parse it.

Is the offer/answer machine prepared for such a case? Can I expect that 
if I manage to pass through a no-body INVITE, the answer/offer machine 
will handle the case later and will call my onOffer?

Any suggestions would be greatly appreciated.

-- 

Kind regards,
Ilia