This document discusses H.323 support in PAN-OS firewalls. It provides an overview of the H.323 protocol and describes several supported scenarios for direct H.323 calls between terminals with and without NAT. It also covers calls that involve an H.323 gatekeeper, noting that PAN-OS supports direct calls signaled through a gatekeeper but not gatekeeper-routed calls or multi-gatekeeper topologies. The document concludes by mentioning that H.323 calls across an IPSec VPN tunnel are supported without NAT.