H.323 Trunk Overview
If you have an H.323 deployment, H.323 trunks provide connectivity to remote clusters and other H.323 devices, such as gateways. H.323 trunks support most of the audio and video codecs that Unified Communications Manager supports for intra-cluster communications, with the exception of wideband audio and wideband video. H.323 trunks use the H.225 protocol for call control signaling and the H.245 protocol for media signaling.
Within Cisco Unified CM Administration, H.323 trunks can be configured using the Inter-cluster Trunk (Non-Gatekeeper Controlled) trunk type and protocol options.
If you have a non-gatekeeper H.323 deployment, you must configure a separate intercluster trunk for each device pool in the remote cluster that the local Unified Communications Manager can call over the IP WAN. The intercluster trunks statically specify either the IPv4 addresses or hostnames of the remote devices.
You can configure up to 16 destination addresses for a single trunk.
When configuring intercluster trunk connections between two remote clusters, you must configure an intercluster trunk on each cluster and match the trunk configurations so that the destination addresses used by one trunk match the call processing nodes that are used by the trunk from the remote cluster. For example:
Remote cluster trunk uses Run on all Active Nodes—The remote cluster trunk uses all nodes for call processing and load balancing. In the local intercluster trunk that originates in the local cluster, add in the IP addresses or hostnames for each server in the remote cluster.
Remote cluster does not use Run on all Active Nodes—The remote cluster trunk uses the servers from the Unified Communications Manager Group that is assigned to the trunk's device pool for call processing and load balancing. In the local intercluster trunk configuration, you must add the IP address or hostname of each node from the Unified Communications Manager group used by the remote cluster trunk's device pool.
To configure secure signaling for H.323 trunks, you must configure IPSec on the trunk. For details, see the Security Guide for Cisco Unified Communications Manager. To configure the trunk to allow media encryption, check the SRTP allowed check box in the Trunk Configuration window.
Gatekeepers are no longer widely used, but you can also configure your H.323 deployment to use gatekeeper-controlled trunks. For details on how to set up gatekeeper-controlled trunks, refer to Cisco Unified Communications Manager Administration Guide, Release 10.0(1).