title: play audio file over VoIP
body: <p>I want to implement a simple VoIP system which can achieve following;</p>
  
  <ol>
  <li>The user uploads a mp3 or wav file and gives a phone number.</li>
  <li>the given phone number is dialed, when the phone is picked, the uploaded mp3/wav file is played. once the whole file is played, the call is hung up.</li>
  </ol>
  
  <p>i want to know if there is any opensource library which supports this?? or an opensource software using which i can achieve this?</p>