Calls dropping after 32 seconds is a common problem in VoIP communications. Below is an explanation of why the problem can occur and how to solve it.
How this problem occurs:
When a SIP call is established between two endpoints, the callee sends the SIP response 200OK in order to confirm that media data (audio) can be transferred between the two endpoints. If the callee side doesn't receive the SIP response "ACK" (meaning acknowledged), the callee sends 200OK several more times before it ends the call when no ACK received. This happens during a 32 seconds time span. However, during the 32 seconds audio is delivered between the two endpoints until it cuts off.
How to solve it:
Switch to TCP: In the Impact Phone clients have an option to set "Transport" either to TCP, UDP or TLS. Set it to TCP. Then it will no longer cut off the calls.
If UDP required: Check your firewall settings to make sure UDP is not blocked on the required ports. also bear in mind that UDP needs a STUN Server.
Please bear keep in mind that Impact Telecom manages your system and that you should never have any problems calling. If you do, please contact Impact Telecom Support.