If you put a videoconferencing endpoint behind a sonicwall and open all needed ports, or even “any” port to the endpoint, the videocall will work fine. However, this is not because (or just because) you are opening the inbound ports. It is also because the sonicwall understand H323 and SIP traffic, specifically the UDP packets that are coming into the system.
However, if you put a LifeSize Videocenter behind a Sonicwall, it will not work, no matter if you open all the ports or not. If you do a packet capture on the Sonicwall, you will see that the firewall is “consuming” the UDP packets. It considers the packets to be an intrusion.
Turning off the deep packet inspection fixes it. Or moving the LifeSize Videocenter outside of the firewall (it is designed to sit on the Internet).