Have a customer that has a remote user. since last week the remote user has not been able to hear or be heard when making a call or receiving a call. Replaced the phone, he had an extra one. same result. He can make a call and you can call him but he answers and nothing. I've had him reboot his modem, I have rebooted the local system. The local system is rel 11.0. Thinking ports are not open or something. What should I check? The user is 2 hours away so I would like to have some idea of what to look for before heading out.