VoIP FAQS Ports
From wiki.IPBRICK.COM
IPBRICK 6
SIP
5060/udp
RTP Audio
50000/udp a 55000/udp (when the IP PBX is connected to the Internet using eth0 as gateway)</br>
60000/udp a 65000/udp (when the IP PBX is connected to the Internet using eth1 or other interface rather then eth0 as gateway - rtpproxy utilization)
RTP Fax T38
40000/udp a 45000/udp (when the IP PBX is connected to the Internet using eth0 as gateway)