Cisco Cisco E-Mail Manager Unity Integration Option Leaflet

 shows a failure on Unified CM active call processing subscriber A. In this model, the 

subscriber is actively processing calls and controlling devices but does not provide the CTI Manager 
connection to the Unified CCE PG. The CTI Manager services are running on all the Unified CM 
subscribers in the cluster, but only the subscribers C and D are configured to communicate with the 
Unified CCE Peripheral Gateway.

The following conditions apply to this scenario:

All phones and gateways are registered with Unified CM subscriber A.

All phones and gateways are configured to re-home to Unified CM subscriber B (that is, B is the 
backup server).

Unified CM subscribers C and D are each running a local instance of CTI Manager to provide JTAPI 
services for the Unified CCE PGs.

If Unified CM subscriber A fails, phones and gateways re-home to the backup Unified CM 
subscriber B.

PG side A remains connected and active, with a CTI Manager connection on Unified CM 
subscriber C. It does not fail-over because the JTAPI-to-CTI Manager connection has not failed. 
However, it will see the phones and devices being unregistered from Unified CM subscriber A 
(where they were registered) and will then be notified of these devices being re-registered on 
Unified CM subscriber B automatically. During the time that the agent phones are not registered, 
the PG will disable the agent CTI desktops to prevent the agents from attempting to use the system 
while their phones are not actively registered with a Unified CM subscriber. Also, they will be put 
into "not ready" state by the system during this transition to avoid routing calls to them as well.

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Unified CM B

Unified CM A

ICM synchronzation messages
Unified CM intra-cluster messages
JTAPI messages
H323 or MGCP messages
SCCP messages

Agent PG A

Fails

Agent PG B