SIPSorcery is merely an experiment and as such I would not try to use it for anything serious... to quote a post by the sipsorcery developer...
"Need an example SIP client in C #.
I tried to deal with http://sipsorcery.codeplex.com/ but little documentation I can not even make or receive calls.
Recommend anything?"
"Yes I'm notoriously bad with documentation, sorry.
More than likely the sipsorcery SIP client is not what you're after. It's a pure SIP implementation with no RTP or audio capabilities which means it's useless as far as a standalone VoIP client that you can use to make and receive calls WITH audio. In other words it can do the SIP signalling side of things but without the audio capabilities that's not much good for a client side application; the sipsorcery project is predominantly server side.
Of late I have been playing around a bit with NAudio with the goal of adding a very rudimentary audio capability to the softphone example but I've no idea when I'll have something working."
Take a look at http://www.iptel.org/ser/ for a good / fuller project with lots of documentation.