title: How to develop SIP (VOIP) application
body: <p>I developed sip application in Android. and now I am developing it in Windows Phone 8. I am new in Windows phone and don't know anything that Which library should be use here? Do Microsoft provide free library for SIP? </p>
  
  <p>Please any suggest me Which way will be best for developing or any source code or library or demo application?</p>