Handshake to start a Gstreamer media session

[fereydoon.vahidi at gmail.com]

I am trying to implement a local Voip service between my two linux PCs. The special characteristic of this voip would be that the two user would be able to send and receive Stereo voice.i managed to program the media layer using gstreamer SDK.( RTP, UDP and PCM)

Now i want to use a simple application to establish this connection and add the gstreamer media to its signalisation. 
SIP is really inflexible and it seems most of Sip stacks have their own media layer that don't fulfill my required audio characteristics . 
Has anyone any experience or idea how i could write a simple handshake for session Establishment? Any tutorials or examples or hints are welcome