title: How to get audio from GSM modem - Not to a speaker but as a RTP stream
body: <p>I have a GSM modem with a serial port and soldered points for MIC and Speaker. Through the serial port I can send AT signalling commands, send SMS and make/receive calls. I had to solder a speaker and a MIC  to the modem card. My problem is that I want to read the audio stream as a RTP stream, possibly through some intermediate hardware/software. My goal is to ultimately get the audio as a RTP stream on some port with some RTP profile. I understand that I need to run a UDP server to serve the audio over a UDP IP-address/port tuple, but how do I get the audio to the UDP server in the first place?  Codec conversion is also something that I am familiar with and am aware that I may need it.</p>
  
  <p>This is a simplified diagram of what I intend to do:</p>
  
  <pre><code> GSM-modem-audio ---*1*---&gt; audio-over UDP(ip-address:port)----&gt;  
        &gt;---*2*--&gt;  Kurento RTPendpoint---*3*---&gt;Kurento-WebRTC endpoint
  </code></pre>
  
  <p>I don't know how to handle part * 1 * piece of the puzzle.</p>