Regarding H323
Several people suggest that H323 is not working on Trixbox 2.0 and that you should stick with Trixbox 1.2.3 if you want H323 functionality.
After having found a working setup for H323<->SIP communication with Trixbox 1.2., we checked if this would work also for Trixbox 2.0. So far there are two versions available for Asterisk on Trixbox 2.0, the default one and a newer one which can be retreived through the TrixBox package repository; there are also three versions of the needed asterisk-addons package, the default one (1.2.4), the one working on Trixbox 1.2.3 (asterisk-addons 1.2.3), and a newer one which can be retreived through the TrixBox package repository.
Sadly enough none of the asterisk and asterisk-addons seem to work on a Trixbox 2.0: the system starts up, but whenever a H323 call is initiated from a H323 terminal, Asterisks get a segmentation fault; after that, Asterisk silently restarts.