title: Is there any way of sending DTMF tones during a call with linphone?
body: <p>I'm trying to send a sequence of DTMF tones during a SIP call from linphone, compiled for the iPhone, in order to do some call management at a local exchange I've set up. I see from the code that the individual digits send DTMF (without audio on the line), but I can't seem to send a string of digits manually. </p>
  
  <p>When I try, I just get a single digit sent. I could put in a delay and timer, but that just doesn't seem the way to go about it - and a long string of tones would take a long time to send with the necessary acknowledgements.</p>
  
  <p>I've read that you can send DTMF as part of a SIP INFO message, but can't find the facility in linphone to construct a SIP INFO message.</p>
  
  <p>Has anyone been able to do this or have any suggestions as to what I could try?</p>