Cannot receive voice calls.

We are having trouble with our Xfinity voice.  We can make calls fine, but we cannot receive calls at all now.  The caller cannot hear us.  The caller either continues to hear ringing or they get call cannot be completed at this time.  I have restarted the router numerous times.  We recently received a new router from Xfinity and this seems to have made the problem even worse.   prior to this router, we would periodically have this issue, but a restart would fix the issue for a week or two.  Help!