/mcpMessage Sequence Charts Redirect to a Device, on page 1449 Redundancy Configuration requires that devices are configured into device pools and are assigned static Cisco Unified Communications Manager groups. Devices register with a particular Cisco Unified Communications Manager server that handles call control signaling. When a server fails, the devices failover to the backup server in the group. When the primary server comes back online, it waits until no active calls exist on the device, then re-homes to the primary Cisco Unified Communications Manager server. Cisco Unified JTAPI informs the applications of this transition by sending a temporary out-of-service message while registering to the backup server. Redundancy in CTI Managers Cisco Unified JTAPI also offers transparent applications for redundancy via the CTI Manager. When the primary CTIManager fails, Cisco Unified JTAPI automatically connects to the backup CTI Manager and communicates the reconnection to applications. Instead of connecting to a single Cisco Unified Communications Manager server, applications now connect to a set of CTIManagers. The applications supply the CTIManager server names when they invoke JTAPI. Cisco Unified JTAPI and the CTIManager maintain bidirectional heartbeat signals to detect a loss of connectivity between them. The CTIManager detects when an application no longer runs and cleans up its allocated resources. The following figure illustrates the“Logical Representation of JTAPI, CTIManager and Cisco Unified Communications Manager in a cluster” After Cisco Unified JTAPI successfully connects to the primary CTIManager, it alternately will attempt to reconnect to the primary or backup CTIManager if the JTAPI connection to the CTIManager fails. Note Figure 12: Logical Representation of JTAPI, CTIManager and Cisco Unified Communications Manager in a Cluster Invoking CTIManager Redundancy When getProvider() method on the CiscoJtapiPeer is called during the application startup, Cisco Unified JTAPI attempts a connection to the first CTIManager in the list and tries a connection to the next CTIManager Cisco Unified JTAPI Developers Guide for Cisco Unified Communications Manager, Release 15 and SUs 150 Features Supported by Cisco Unified JTAPI Redundancy