With some more experimentation, the hangup only occurs when the call is initiated from the Grandstream. If the Grandstream answers a call no hangup at 17:28.
I turned on the debugging on the Grandstream and I see an entry from the GS to the asterix server with:
Does it happen on both, incoming and outgoing calls ?
Are you using a static or dynamic IP ?
Are you only using ATA’s or IP phones as well ?
If so try a soft phone and see what happens, you could try that directly with your provider and cut the Asterisk out of the way and see if that is working.
Or try it on the inside as an extension as well and see if your ATA’s are the problem.
Just a few thoughts to find out what is causing the problem.
I have done more testing. First I determined that it wasn’t the sip trunk, because it occurred from ATA to ATA that didn’t go off the lan with our asterisk server. Then I determined it is related to the ATA’s since softphone to softphone didn’t show the problem.
So its something tied into the Grandstream HT-286’s that is doing it. I don’t see anything relevant in their configuration.