title: Sinch iOS SDK no sound sometimes during conference calls
body: <p>We have an app that calls two parties, and when they accept the call we dial them into the same conference call. One issue we have observed is that sometimes both parties will be connected, but one side isn't able to hear the other side. In these cases I usually verify that two calls were indeed created by Sinch (via the Sinch call logs/callbacks) and that they are using the same conference ID (via our own logs.)</p>
  
  <p>I have seen two different types of problems related to this -
  1. The "callDidEstablish" delegate method was hit, but a Sinch call was never actually created according to the Sinch logs.
  2. Both calls were created, but there is just no audio.</p>
  
  <p>I am not sure if (2) could potentially be an issue with the AudioSession? Any guidance in helping debug this type of issue would be much appreciated. Again, this doesn't happen every time, but we do see it quite often.</p>