Calls being cut off after 6 seconds


I have a phone that is connected over the internet to FreePBX. That phone -and that phone only- cuts off calls after 6 seconds. It’s quite weird that we have another phone is connected over the internet fine.

No idea what is going on- any ideas?


Investigate the Nat transversal through all the routers involved to get to that phone

How would I go about doing that?

Reading of the wiki here (as many times as it takes), a little googling about SIP nat traversal, reading all the the FM’s of all the routers through which the connections pass between the server and the extension? There is no one size fits all here, and is usually the far end router configuration when one extension works and one doesn’t.