Remove called party from sip_audio_session.py on incoming

darcs-hash:20090326124509-58103-a2ee61212b03192b001b8597b950df4f165c9e11
Fix for setting Invitation.transport on incoming

darcs-hash:20090326130814-58103-5b496422b8b4e8cf456ae4435f382e4b31fb8e5f