This is a SDK that lets you create a VoIP solution with SIP protocol.
ABTO Software VoIP SIP SDK is a development tool that helps create a solution quickly. It is possible to build VoIP softphone that can dial and receive calls on your computer. It will let you add VoIP features into your software applications too. The system is iOS5 compatible. Thus applications for VoIP directly or other applications that include VoIP will work with iPhone. The tool is compatible with SIP and RTP protocols. It is possible to build applications that support video and voice calls. SIP registrar for SIP server support can be provided. The SDK is also compatible with STUN and other IETF standards such as SER, OpenSER and Asterisk. Support for several codecs is available for input voice and video processing. These include G.711-ALaw, G.711-muLaw, G.729, Speex, Theora, GSM, H.263, H.263+ and H.264.
This is a tool that is strictly for the specialists. No novices will be able to easily understand the stuff. The SDK is for the specialized developers who deal with VoIP technology and specifically for the SIP protocols. To work with the other protocols supported also, you need specialized knowledge. However, it is quite easy to work with for the right kind of people. Help documentation in PDF and CHM formats are available. This is a good product and has many useful features. If you have a need, here is a good candidate for trying out.