Hi fellow developers :)

I plan to build a C# softphone, but I'm not very secure in my knowledge, so I've done some research. My softphone must be able to register with a SIP service provider. That's priority #1. So my research has included this condition, too. Long story short, I've found this great VoIP SIP SDK, and I've already tried the many sample programs which also seem good. Because I'm always searching for the best, I tend to be a little (means: very) insecure, so I'd like to hear other people's opinion about the issue. If anyone would like to help me, here you can find the program: http://www.voip-sip-sdk.com/p_193-how-to-build-a-c-sip-softphone-client-that-can-register-with-a-sip-service-provider-voip.html
A little review of it will be a great help for me! (Is it stable, trustworthy, etc...?)

Thanks in advance:

Blane