VoIP SDK built on open standards, leveraging SIP (Session Initiation Protocol) to create, run and terminate multi- media sessions. They are built on popular codecs for voice and video (include G.711, G.722.1, G.723.1, G.729(b), GSM, iLBC, SPEEX(WB), AMR-WB, H.263, H.263-1998 and H.264), and the SIP SIMPLE standard for Instant Messaging and Presence SIP SDK includes SIP activeX , SIP OCX , SIP DLL , SIP Lib and SIP Cab, so you can use the one you like the most