Cisco Cisco IP Contact Center Release 4.6.1 Guía De Diseño

and all the CTI Manager messaging would have to be routed across the cluster to the original subscriber.   
It is important to distribute devices and CTI applications appropriately across all the call processing 
nodes in the Unified CM cluster to balance the CTI traffic and possible failover conditions.

The external CTI applications use a JTAPI user account on the CTI Manager to establish a connection 
and assume control of the Unified CM devices registered to this JTAPI user. In addition, given that the 
CTI Managers are independent from each other, any CTI application can connect to any CTI Manager 
to perform its requests. However, because the CTI Managers are independent, one CTI Manager cannot 
pass the CTI application to another CTI Manager upon failure. If the first CTI Manager fails, the external 
CTI application must implement the failover mechanism to connect to another CTI Manager in the 
cluster. 

For example, the Agent PG handles failover for the CTI Manager by using its duplex servers, sides A 
and B, each of which is pointed to a different subscriber in the cluster, but not at the same time. The PG 
processes are designed to prevent both sides from trying to be active at the same time. Additionally, both 
of the duplex PG servers use the same JTAPI user to log into the CTI Manager applications. However, 
only one Unified CM PG side allows the JTAPI user to register and monitor the user devices to conserve 
system resources in the Unified CM cluster. The other side of the Unified CM PG stays in hot-standby 
mode, waiting to be activated immediately upon failure of the active side.

 shows two external CTI applications using the CTI Manager, the Agent PG, and the 

Unified IP IVR. The Unified CM PG logs into the CTI Manager using the JTAPI account User 1, while 
the Unified IP IVR uses account User 2. Each external application uses its own specific JTAPI user 
account and will have different devices registered and monitored by that user. For example, the 
Unified CM PG (User 1) will monitor all four agent phones and the inbound CTI Route Points, while the 
Unified IP IVR (User 2) will monitor its CTI Ports and the CTI Route Points used for its JTAPI Triggers. 
Although multiple applications could monitor the same devices, this method is not recommended 
because it can cause race conditions between the applications trying to take control of the same physical 
device.

Unified CM CTI applications also add to the device weights on the subscribers, adding memory objects 
used to monitor registered devices. These monitors are registered on the subscriber that has the 
connection to the external application. It is a good design practice to distribute these applications to CTI 
Manager registrations across multiple subscribers to avoid overloading a single subscriber with all of the 
monitored object tracking.

ICM

PG

76605

Unified CM Publisher

(CTI Manager and

CallManager Services)

Unified CM Subscriber

(CTI Manager and

CallManager Services)

Unified CM Subscriber

(CTI Manager and

CallManager Services)

JTAPI user 1

logs in

Agent 1

IP IVR

JTAPI user 2 logs in

User 2 CTI ports

Agent 2

Agent 3

Agent 4