====== H.225 Trunk ======
  * Also called gatekeeper controlled intercluster trunk
  * Used to connect: 
    * CUCM 3.2 or later
    * All other H.323 device
    * CUCME

===== Configuration =====

==== CUCM Gatekeeper ====
  * Under **Device > Gatekeeper > Add New** add gatekeeper
{{cucm-h225-tk1.png|}}

==== CUCM H.225 Trunk ====
  * Under **Device > Trunk > Add New** add trunk
{{cucm-h225-tk2.png|}}

  * Associate previously configured gatekeeper with the trunk
{{cucm-h225-tk3.png|}}

==== CUCM Route Pattern ====
  * Configure Route Pattern to point to trunk

==== IOS Gatekeeper ====
  * The Gatekeeper does not need to be configured with the CUCM IP as it is learned when the CUCM registered to it
  * The technology prefix is like a specialty of the registered endpoint 
    * E.g. 2# could means video
    * If we dial 2#12345, the gatekeeper will not only look at the prefix but also the technology prefix before deciding on which entities to forward the call
  * Bandwidth
    * If default is specified instead of a zone name, it will apply to all zones.
    * Unit in kbps and is twice the bandwidth of the audio codec payload (without layer3 overhead)
      * G.711 = 2 x 64kbps = 128kbps
      * G.729 = 2 x 8kbps = 16kbps
    * Interzone
      * Applies to all calls coming in to and going out of the specified zone (interzone calls)
    * Total
      * Applies to all calls in the specified zone (interzone and intrazone calls)
    * Session
      * Applies to each call in the specified zone (specifies the max bandwidth per call)
<code>
gatekeeper
  bandwidth {interzone | total | session} {default | zone <zone-name>} <kbps>
</code>
{{cucm-h225-tk4.png|}}

===== PSTN Backup =====
  * If the Gatekeeper CAC reject the call, we can use Route list to reroute the all over the PSTN
{{cucm-h225-tk5.png|}}