[Freeswitch-users] What ports are really necessary?

I'm running a simple switch. No phones are connected to the system from outside of my local network. The only wan connections I have are a couple of voip providers. None of my phones on the lan call outside of the lan. All they talk to is the switch. I see a bunch of ports listed at http://wiki.freeswitch.org/wiki/Firewall but don't know if I need them all. I suspect I don't. I want to close up the firewall as much as I can. Thanks, Jim.