title: Make voice and video call through internet with our application?
body: <p>I want to develop <em>voice and video call</em> through <strong>our application users</strong> in android like Wechat Application. How can i doing this? 
  I have searched in Google but i didn't get any exact reference or samples. Can anyone explain and give some sample source and references for doing this functionality? 
  And I have few confusion about SIP and VOIP which one im going to use for support android versions 2.2 to higher versions applications?</p>