We are having an issue with calls dropping from one of our Trunks. We have run a SIP debug and find that there is a timeout on a non-critical invite. During one of the INVITE transactions we are not seeing a response from the provider and the system times out and drops the call. They are claiming this has to do with the lack of UPDATE in the Allow header of the SDP. What is this function and how would this cause the timeout.
We are running V13 FreePBX Distro. I can provide any details needed to solve this. We have been working on it with the provider for 6 weeks now without resolution.