Zone Prefixes
A zone prefix is the part of the called number that identifies the destination zone for a
call. Zone prefixes are usually used to associate an area code to a configured zone, and
they serve the same purpose as the domain names in the H.323-ID address space.
The Cisco gatekeeper determines whether a call is routed to a remote zone or handled
locally. To illustrate, consider the example given in Figure 8-19 and Example 8-3.
According to this configuration excerpt, gatekeeper Corp-GK forwards 408....... calls to
the San Jose gateway. Calls to area code 281 are handled locally.
Figure 8-19 Zone Prefix
Example 8-3 Zone Prefix Configuration
Chapter 8: Configuring H.323 Gatekeepers 469
V V
WAN
Zones
Corp-GK
172.22.2.3
Houston
281-XXX-XXXX 408-XXX-XXXX
San Jose
GK-A(config)#gatekeeper
GK-A(config-gk)#zone local Houston cisco.com 172.22.2.3 1719
GK-A(config-gk)#zone local SanJose cisco.com
GK-A(config-gk)#zone prefix Houston 281.......
GK-A(config-gk)#zone prefix SanJose 408.......
When the San Jose gateway receives the request, the gatekeeper must resolve the address
so the call can be sent to its final destination. An H.323 endpoint with that E.164 address
might be registered with the San Jose gateway, in which case the San Jose gateway
returns the IP address for that endpoint. However, it is possible the E.164 address
belongs to a non-H.323 device (for example, a telephone or an H.320 terminal). Because
non-H.323 devices do not register with gatekeepers, the San Jose gateway cannot resolve
the address. The gatekeeper must be able to select a gateway that can be used to reach
the non-H.