The IM and Presence Service allows enterprise users to control their
Cisco Unified IP Phone through
Microsoft Office Communicator, a third party desktop IM application. The
Microsoft Office Communicator client for this integration can run on either Microsoft Live Communications Server (LCS) 2005 or Microsoft Office Communications Server (OCS) 2007.
Microsoft Office Communicator sends session-initiating requests to the CTI Gateway on IM and Presence to control
Cisco Unified IP Phones registered in
Cisco Unified Communications Manager, as illustrated in the following figure. The CTI Gateway forwards the requests to the CTI Manager on
Cisco Unified Communications Manager. The
Cisco Unified Communications Manager returns the events to the
Microsoft Office Communicator application using the same path in the opposite direction.
Figure 1. Integration Overview
IM and Presence supports CTI connections with up to eight
Cisco Unified Communications Manager nodes; you can configure up to eight CTI connection addresses on IM and Presence.
Microsoft Office Communicator sends session initiating requests to IM and Presence. These requests are routed in a round-robin sequence to the CTI connection addresses configured on IM and Presence. For example, the first request is routed to first CTI node, second request to next CTI node and so on. Priority is assigned to CTI connection addresses in the order in which they are configured. If a dual node IM and Presence cluster is deployed, you must use a load balancer. In this scenario, the load balancer sends the session initiating requests in a round-robin sequence from
Microsoft Office Communicator clients to the IM and Presence publisher and subscriber nodes. There is a maximum of two nodes in a IM and Presence cluster when it is configured to support
Microsoft Office Communicator Remote Control Client.
In a dual node IM and Presence cluster, a load balancer can be used to round-robin the session initiating requests sent from
Microsoft Office Communicator clients to the publisher and subscriber IM and Presence nodes.
When the CTI Gateway on IM and Presence starts, it connects to all CTI connection addresses in the configured list, and monitors these connections by sending periodic heartbeat messages. When a
Microsoft Office Communicator user signs in,
Microsoft OCS sends a SIP INVITE request with a CSTA body to the CTI Gateway to monitor the
Cisco Unified IP Phone for the user. The CTI Gateway creates a session for that
Microsoft Office Communicator user, and uses the load balancing mechanism to send session initiating requests from that user to any of the CTI connection addresses.
Once the CSTA application session is established,
Microsoft Office Communicator and CTI Gateway exchange a sequence of SIP INFO messages for activities such as monitoring devices, making calls, transferring calls, or changing the status of controlling devices. This message exchange is sent over the same CTI connection address with which the initial session was established.
If connection to any of the CTI Managers fails, outbound call requests from
Microsoft Office Communicator are returned until the connection comes back into service. If a
Cisco Unified Communications Manager node is down, the CTI Gateway will make periodic attempts to re-establish a connection to it. When the
Cisco Unified Communications Manager node comes back in service, the CTI Gateway will reconnect to it and monitor the connection. In this case, when
Microsoft OCS sends an (in-session) SIP INFO request, the CTI Gateway will have a different CTI Manager connection ID because of a new connection.
Microsoft Office Communicator sends a new SIP INVITE message, but the
Microsoft Office Communicator user is not required to sign in again.