Shawn, the 7100 has no way to know that the remote calling party has hung up without the provider terminating the call. From the 7100 side, I would make sure you've run ERL tests just to make sure the lines are at the correct impedence, but assuming that has been done, you'd need to contact the provider to troubleshoot from their end. Thanks
Shawn, some additional clarification about what your provider will likely need to do. The service provider will likely need to provision your lines for Network Disconnect, also called Forward Disconnect. A Network Disconnect signal is a period where the network removes voltage between tip and ring, which we will detect and use as a signal to tear down the call.