title: VoIP/SIP to make calls with background music
body: <p>I'm looking to create an app where two users can chat to each other while one of them plays music in the background. The music will be played from a file and will need to be mixed with the input from the microphone so that the other user can hear it too.</p>
  
  <p>I've been looking at PJSIP which looks like it can do this but I was just wondering if there where any easy to implement alternatives that were more objective c and less plain c?</p>