Quote Originally Posted by zcnkac View Post
Aren't these ports what the CPE (linksys/grandstream) selects for the local media stream, rather than what the CLEC media server use ? Linksys by default uses - 16384-16482. Usually only these ports need to be forwarded. In another thread someone mentioned that the router might map the ports to something else externally and therefore a lot more ports need to be forwarded.

I have Asterisk and limit it to ports 14020-14030. I have a Linksys WRT running Tomato and forward only these ports.
I guess it depends on router, but am not 100% sure of the technical reasoning. What I do know is that most of the time when people report issues and we check logs, we see the traffic coming in from the remote media gateway on a port within to 5004-65000 range and the router blocking it or misrouting it. Some routers let it through, but the ones that analyze it sometimes see the connection as "unknown" since it's from a different IP on a port not already being used, etc.