/mcpTable 6 lists the roles of the call control components in this architecture and the services they provide.
Table 6. Components for Call Control
Module
Component
Description
Call Control
Cisco Unified Communications Manager
(Unified CM)
Provides call routing and services, dial plan, and
bandwidth management; and enables Cisco
Jabber desk phone control
Cisco Unified Communications Manager
IM and Presence Service
Provides Cisco Jabber support for instant
messaging and user-based presence and third-
party federation
Cisco Integrated Services Router (ISR)
Provides Survivable Remote Site Telephony
(SRST) to support call control functions during a
WAN outage
Recommended Deployment
For call control in the Cisco Collaboration on-premises Preferred Architecture, we recommend the following:
•
Deploy a single Cisco Unified CM cluster for an enterprise with a central site and remote offices. Deploy call
processing subscribers in pairs for scalability and redundancy.
•
Add additional Cisco Unified CM clusters for very large sites or for geographic and/or organizational separation.
Configure SIP trunks to interconnect individual Cisco Unified CM clusters.
•
Deploy a pair of IM and Presence Service servers in a cluster configuration. For enterprise deployments, you can
add more pairs for scalability. (Increased scalability does not apply to midmarket deployments.)
•
Enable SRST on the Cisco ISR as a backup service at remote sites to provide high availability.
•
Enable Apple Push Notification service (APNs) for Apple iOS devices running Jabber for iPhone and iPad, so that
these clients continue to receive incoming call and messaging notification even when running in the background.
For Apple iOS devices operating in a constrained network without Internet access Local Push Notification
Service (LPNS) can be deployed to deliver notifications for voice calls only. LPNS does not deliver messaging
notifications. LPNS also helps to minimize delays for incoming calls to the Apple iOS devices operating in
unconstrained and constrained networks.
•
Enable Android Push Notification service for devices running Jabber for Android, so that these clients continue
to receive incoming call and messaging notification even when running in the background.
Cluster Recommendations
Cisco Unified CM and IM and Presence support clustering, which is the grouping of nodes that work together as a
single logical entity. The publisher node contains the cluster's configuration database, which is replicated to the call
processing subscriber nodes and TFTP nodes in the cluster.
Clustering provides an automatic redundancy mechanism for endpoints and for Cisco Unified CM services, such as
the ability to receive and process incoming calls. To provide 1:1 redundancy, deploy call processing subscribers and
TFTP nodes in pairs. (Figure 6) While the call processing subscribers provide endpoint registration and call processing
capabilities, the TFTP nodes provide configuration and firmware updates to endpoints.