I tried to integrate to lync 2013 using circuit ID. my feedback is simple. DO not try to connect to the trunk directly to the mediation server for inbound calls. The trunk does not speak rtcp (at least my line did not), they have no staff to help you. So be prepared to be on your own. Alos, the codec that is passed on the inbound call, appears to be flawed and errors out. there was no way to get around this error. I wasted three monthes of my life on it. I will not do that again.
Make sure your trunk is simply LYNC certified. Otherwise, you af best using an audiocodes.