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 must run on Microsoft Office Communications Server (OCS) 2007 R2.
Microsoft Office Communicator
sends session-initiating requests to the CTI Gateway on
IM and Presence Service 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 Service 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 Service.
Microsoft Office Communicator
sends session initiating requests to
IM and Presence Service. These requests are routed in a round-robin sequence to the
CTI connection addresses configured on
IM and Presence Service. 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 Service 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 Service publisher and subscriber nodes. There is a maximum of two
nodes in an
IM and Presence Service cluster when it is configured to support
Microsoft Office Communicator Remote
Control Client.
In a dual node
IM and Presence Service 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 Service nodes.
When the CTI Gateway on
IM and Presence Service 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.