VaxTele SIP Server SDK - Version 2.0 VaxTele SIP Server SDK (Software Development Kit) is a new and flexible approach to develop SIP based VoIP servers, IP-PBX, SIP gateways, SIP PBX. It is really easy to develop IP-Telephony, PC to PC and PC to Phone services by using VaxTele SIP Server SDK. VaxTele SIP Server SDK includes COM (Component Object Model) components, and can be used in almost all software development tools and languages (VC++, C#, VB.NET, Delphi, Borland C++ etc.) to accelerate the development and ensure a successful VoIP product or application. Fairly basic and easy to understand sample source codes are also available to download.