na veel zoeken heb ik via Vocaltech toch enige info weten te krijgen. Was via de normale hoofdpagina niet te vinden. zie hier:
Firewall/Proxy
CheckPoint(tm) FireWall-1(tm), of CheckPoint Software Technologies, Inc., the market share leader in network security software provides integrated, secure support for Internet Phone(tm).
It is also possible to use Internet Phone over other Firewalls, by opening the two channels it works with:
1. TCP Port 6670 (decimal) to remote system: The port used to connect to the Internet Phone Servers.
2. UDP Port 22555 (decimal). All audio is passed through this port on both local and remote machine.
3. TCP Port 25793 (decimal) to remote system: The port used to connect to the Addressing Server(for Version 4 & 5).
4. TCP Port 1490. This port is for the Conference engine (whiteboard/chat/file transfer)(for Version 4 & 5).
Check if these requirements are accepted by your company's security policy.