My Boss has purchased a couple of Creative VOIP Blasters without reading fine print on the box(LAN & Firewall are not supported) My question is does anyone know what ports the ITU-T H.323 V2 Voice-over-IP protocol uses so that I might configure the router on our LAN to allow this device to work? Or if not is there a port sniffer that might allow me to figure out what port the gadget is trying to use?
Any help with this would be greatly appreciated.
It’s not that simple I’m afraid. H.323 comprises a number of protocols including H.225, Q.931, H.245, RTP and RTCP. The setup procedure is very complicated and the ports are allocated dynamically during call setup. TCP is used for call set up and UDP is used for media transmission.
What you probably need is a Gatekeeper. This will manage admission control to the Internet and, optionally, will route the calls to their destination if they are unreachable from within your LAN.
To have a good look at what’s going on, download Voice2Sniff. It’s a Ethernet sniffer modified for H.323 decoding, and it’s free.