Hi gang, we recently came across an issue when trying to use FaceTime on an iMac. It simply wouldn’t connect when calling or when receiving a call. Dialing appeared to work at first, but as soon as the intended user clicked to answer the incoming FaceTime call, the call would disconnect.
In an effort to troubleshoot the issue, we turned off the firewall, reset the the router, restarted the iMac and even reset the AppleID. Still no luck… Then it dawned on me, maybe FaceTime can only be used on one device at a time. We turned off FaceTime on the iPhone which was using the same AppleID and BINGO! It worked!!!
Not sure if this is just a temporary bug with iOS 6 and/or Mountain Lion, but if you happen to have a similar issue, try turning off your phone’s FaceTime settings temporarily while you use your Mac. The toggle for the FaceTime app can be found under Settings > FaceTime.