Cisco Unified CallManager System Guide, Release 4.2(3)
Cisco Unified Communications Overview
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Cisco Unified Communications Overview

Table Of Contents

Cisco Unified Communications Overview

Internet Ecosystem

Cisco Unified Communications Support


Call Processing



Cisco Unified Communications Network

Where to Find More Information

Cisco Unified Communications Overview

Multiple communication networks exist as entirely separate entities, each serving a specific application. The traditional public switched telephone network (PSTN) time-division multiplexing (TDM) network serves the voice application; the Internet and intranets serve data communications.

Business requirements often force these networks to interoperate. As a result, deploying multiservice (data, voice, and video) applications such as unified messaging or web-based customer contact centers requires expensive and complex links between proprietary systems, such as private branch exchanges (PBXs) and standards-based data networks.

The traditional enterprise communication takes place on two separate networks:



Internet Ecosystem

Over time, the Internet (and data networking technology in general) encompassed the traditional traffic types. This convergence recently started to absorb voice and video as applications into the data network. Several large Post, Telephone, and Telegraph (PTT) carriers use packet switching or voice over ATM as their backbone technology, and enterprise customers accept virtual trunking, or connecting their disparate PBXs via their wide-area data network, to avoid long-distance charges.

By converging these previously disparate networks into a single, unified network, you can begin to realize savings in multiple areas, including lower total cost of ownership, toll savings, and increased productivity.

Cisco Unified CallManager and Cisco Unified IP Phones provide an IP telephony solution that operates on an IP infrastructure. The clustering architecture of Cisco Unified CallManagers allows you to scale to a highly available voice-over-IP (VoIP) network.

Cisco Unified Communications Support

Cisco Unified Communications support encompasses the following components:

Converged client devices


Directory services

Call processing

Telephony/data applications

Network management

Service and support

Cisco Unified Communications solutions enable you to

Deploy IP-enabled business applications

Implement a standards-based open architecture

Migrate to a converged network in your own time frame

Cisco Unified Communications support enables you to move from maintaining a separate data network and a closed, proprietary voice PBX system to maintaining one open and standards-based, converged network for all your data, voice, and video needs.


The following list includes the major Cisco Unified Communications voice and video applications:

Cisco Unified CallManager—This software-only call-processing application distributes calls, features, phones, regions, and groups over an IP network.

Cisco Unity—The Cisco Unity messaging application provides voice messaging to enterprise communications.

Video—IP-TV and IP-video conferencing products enable distance learning and workgroup collaboration.

Cisco Unified IP IVR—As an IP-powered interactive voice response (IVR) solution, Cisco Unified IP IVR, combined with Cisco IP AutoAttendant, provides an open and feature-rich foundation for delivering IVR solutions over an IP network.

Cisco Unified CallManager Attendant Console—This flexible and scalable application replaces the traditional PBX manual attendant console.

Cisco IP SoftPhone—The Cisco IP SoftPhone, a software, computer-based phone, provides communication capabilities that increase efficiency and promote collaboration.

Cisco Personal Assistant—Cisco Personal Assistant selectively handles calls and helps you make outgoing calls. Cisco Personal Assistant provides rule-based call routing, speech-enabled directory dialing, voice message browsing, and simple ad hoc conferencing.

Call Processing

Cisco Unified CallManager, a software-only call-processing application, distributes calls and features and clusters phones, regions, and groups over an IP network, which allows scalability to 30,000 users and triple call-processing redundancy.

Cisco Unified CallManager provides signaling and call-control services to Cisco-integrated applications, as well as to third-party applications.


The following list shows the components of the infrastructure layer of Cisco IP telephony:

Media convergence servers

General voice products for Cisco Unified Communications Solutions


Integrated IP telephony solution

Voice trunks

Voice gateways

Toll bypass products

IP protocols such as MGCP, H.323, and SIP


Cisco delivers the following IP-enabled communication devices:

Cisco Unified IP Phone 7970

Cisco Unified IP Phone 7960

Cisco Unified IP Phone 7940

Cisco Unified IP Phone 7912

Cisco Unified IP Phone 7910

Cisco Unified IP Phone 7905

Cisco Unified IP Phone 7902

Cisco Unified IP Conference Station 7936

Cisco IP Conference Station 7935

Cisco IP SoftPhone

Cisco Unified IP Phone Expansion Module 7914

Cisco Unified Communications Network

The Cisco Unified Communications network includes the following components:

Cisco Unified CallManager

Cisco Unified IP Phones

IOS platforms

Digital gateways

Analog gateways


Conferencing (hardware/software)

Media Termination Point (MTP)

Music On Hold (MOH)


Inline power modules (10/100 Ethernet switching modules)

Cisco IP SoftPhone

Control from the Cisco Unified IP Phone to Cisco Unified CallManager uses skinny client control protocol and, independently, desktop computer to Cisco Unified CallManager, as an H.323 gatekeeper that is using H.225/H.245 over transmission control protocol (TCP).

Where to Find More Information

Related Topics


System Configuration Overview

Device Support

Understanding Cisco Unified CallManager Voice Gateways, page 36-1

Transcoders, page 22-1

Conference Bridges, page 21-1

Additional Cisco Documentation

Cisco Unified CallManager Configuration, Cisco Unified CallManager Administration Guide

Device Defaults Configuration, Cisco Unified CallManager Administration Guide

Cisco Unified IP Phone Configuration, Cisco Unified CallManager Administration Guide

Gateway Configuration, Cisco Unified CallManager Administration Guide

Transcoder Configuration, Cisco Unified CallManager Administration Guide

Conference Bridge Configuration, Cisco Unified CallManager Administration Guide

Cisco Unified CallManager Features and Services Guide

Cisco Unified Communications Solution Reference Network Design

Cisco Unified IP Phone user and administration documentation

Gateway documentation