VOIP SIP Phone SDK DLL allows PC-PC, Pc-phone calls with realtime Instant Messaging Sessions over the Internet with SIP Protocol. With this SDK, one can create a program to connect and start speaking with anyone with a Direct IP Address or use REALM Gateway/Gatekeeper Service Providers Username and Password to connect to/from PSTN Lines. Also available is an ActiveX Control Embedded on a Web Page. SIP SDK provides tools and components to quickly add SIP (Session Initiation Protocol) based dial and receive phone calls feature in your web pages and software applications. It accelerates the development of SIP based soft phone with your own GUI (graphical user interface) and brand name. SIP SDK includes SIP activeX , SIP OCX , SIP DLL , SIP Lib and SIP Cab, so you can use the one you like the most. It is really easy to incorporate SIP controls in your web pages and/or applications. Sample source codes are available to download. SIP SDK can also be used to develop softphone for MS Windows Mobile based Pocket PC and Hand-Held devices. It delivers superior voice quality by integrating advanced digital voice processing features including acoustic echo cancellation, noise cancellation and adaptive jitter buffering. For more details, please visit the features link.