Cisco Cisco Customer Voice Portal 8.0(1)

The ISN’s assigned Gatekeeper must know whether it “owns” the destination endpoint, or whether it 
belongs to another Gatekeeper. If the endpoint is:

In the ISN Gatekeeper’s zone, then the ISN Gatekeeper can determine it directly. 

In a different zone, the ISN Gatekeeper must determine which Gatekeeper does own it. 

An efficient way to do this is by using Gatekeeper zone commands. For example, suppose that the ISN 
Gatekeeper (GK-A) controls Zone A, which supports numbers in the 408 area code; while GK-B controls 
Zone B, which supports the 617 area code. Instead of having GK-A send out queries to determine which 
Gatekeeper owns 617 numbers, GK-A can be configured using a zone prefix command so that it 
“knows” that GK-B owns them. This means that, whenever the ISN requests destination information for 
a 617 number, the GK-A can immediately communicate with GK-B to determine the correct endpoint. 

For more information on Gatekeeper IOS commands, see the Cisco IOS documentation. For detailed 
examples of how to configure Gatekeepers for use with the ISN, see the Cisco Internet Service Node 
(ISN) Configuration and Administration Guide. 

A Voice Gateway can provide access to a Time-Division Multiplexing (TDM) switching network; or it 
can be connected to an ACD, PBX, or to one or more phones. 

In IP transfer mode, once the Gatekeeper has determined the destination endpoint name during ARQ 
processing, the Gatekeeper must then find the endpoint’s IP Address. The Gateways provide this 
information when they register with their Gatekeeper.

As discussed in the 

one way to manage the mapping of the transfer information to destination endpoints is by having the 
Gateways pass a list of their supported E164 numbers when they register with their Gatekeeper. This is 
done using the register e164 command for each dial-peer destination pattern that the Gateway should 
register with the Gatekeeper. Only fully-qualified destination patterns (that is, completely defined 
numbers with no wild cards) may be registered in this manner, and different Gateways may not register 
with the same numbers.

Gateways should be configured to notify their Gatekeeper (through H.323 RAI message) if they are 
unable to accept additional calls. This will prevent the Gatekeeper from selecting those Gateways as 
destination endpoints for ISN IP mode call transfers.

It is expected that Gateways will provide access to call center ACDs in many ISN implementations. Care 
must therefore be taken to configure the Gateway dial-peers to conform with ACD dial-plan 
requirements. A discussion of how this may be accomplished is given in the Examples section.

When the call is being transferred, the ISN Voice Browser negotiates the codec between the ingress 
Gateway and egress Gateway (or CallManager) for the rtp packetized voice connection. Note that the 
Voice Browser merely proxies the codec capability set between the ingress and egress gateways. If the 
desired transfer codec is G.729, for example, then the terminating Gateway must be configured with 
G.729 as its default (highest preference) codec.