I've got an issue where throughout the day (it's very random)some users cannot hear the other end of the call and these are extension to extension calls. I'm new to Mitel and I have a 3300 MXe III and the handsets are a mixture of 5304's and 5312's. Everything else on the network works as expected without any issues. So I'm stumped as to what to check for on the 3300 to make sure everything is proper. I'm not the phone guy, but having to troubleshoot this since he is out of town. There doesn't seem to be a problem with external calls, only in-house.