Calls drop 50 minutes into a call.
This may occur if we don't get a response to our 'keep alive'
What happens is our switch sends a SIP 'keep alive' after 50 minutes to make sure the call is still active. It does this be sending a SIP reINVITE for the live call, in which we expect a 200 OK response, that we then ACK back. If no response is receive, the call is terminated by our switch.
We would have to investigate the call logs to confirm the above and if confirmed then the settings on your PBX as to why it is not responding to reINVITEs.
If you require this investigated further please open a support ticket via http://support.thinktel.ca/index.php/contact or you can contact us by phone at 866-928-4465 Options 1-3-1