http://en.wikipedia.org/wiki/Session_Initiation_Protocol http://en.wikipedia.org/wiki/Session_Initiation_Protocol There are 2 main VOIP protocols right now you

http://en.wikipedia.org/wiki/Session_Initiation_Protocol http://en.wikipedia.org/wiki/Session_Initiation_Protocol There are 2 main VOIP protocols right now you can choose from. H323 and SIP. H323 was developed my the telecom industry and its a binary format so its more of a pain in the ass to develop form. SIP looks like HTML where all the commands it uses, like to register, call, hangup, add someone to the conference, all are in ASCII and are human readable. Heres an example of a SIP packet: REGISTER sips:ss2.biloxi.example.com SIP/2.0 Via: SIP/2.0/TLS client.biloxi.example.com:5061;branch=z9hG4bKnashds7 Max-Forwards: 70 From: Bob <sips:bob@biloxi.example.com>;tag=a73kszlfl To: Bob <sips:bob@biloxi.example.com> Call-ID: 1j9FpLxk3uxtm8tn@biloxi.example.com CSeq: 1 REGISTER Contact: <sips:bob@client.biloxi.example.com> Content-Length: 0 If you were looking at the data of a SIP REGISTER it would look just like that, whereas H323 would just be a bunch of crazy gibberish without the proper decoding.