Content

| 7.4 |  | Cisco IP Telephony |
| 7.4.1 |  | Introducing the Cisco IP telephony solution |

Voice over Internet Protocol (VOIP) is probably the most feasible among today’s technologies for data, voice and video integration. VOIP is the technology that uses Internet Protocol to transmit voice conversations over a data network such as an intranet or the Internet.

The Cisco IP Telephony Solution relies on the stable foundation of Cisco multiprotocol routers and Catalyst multilayer LAN switches, which are the building blocks in enterprise networks. Cisco CallManager is the heart of an IP Telephony solution.

Cisco CallManager
Cisco CallManager is the software-based call-processing component of the Cisco IP telephony solution and essentially the heart of the IP telephony solution. The software extends enterprise telephony features and functions to packet telephony network devices such as IP phones, media processing devices, voice-over-IP (VoIP) gateways, and multimedia applications. Additional data, voice, and video services such as unified messaging, multimedia videoconferencing, collaborative contact centers, and interactive multimedia response systems interact with the IP telephony solution through Cisco CallManager's open telephony application programming interface (API).

The Cisco CallManager software includes a suite of integrated voice applications that perform ad-hoc voice conferencing and browser-based attendant console functions. The key benefit of all of these voice applications is that special-purpose voice processing hardware is not required.

Supplementary and enhanced services such as hold, transfer, forward, conference, multiple line appearances, automatic route selection, speed dial, and last-number redial are available on Cisco CallManager. Cisco CallManager also provides extension mobility so users can log in to any IP phone and the extension and the individual's dial privileges are applied to the phone regardless of their location. This gives users the ability to access all of their personal phone features, such as fast dials, personal contacts, voice mail, productivity applications, and more from any IP phone when they are away from their desktop.

Multiple Cisco CallManager servers are clustered and managed as a single entity. The capability of clustering multiple call-processing servers on an IP network is unique in the industry. Scalability for up to 10,000 users per cluster is provided. By interlinking multiple clusters, system capacity can be increased to up to 100,000 users per multiple cluster system. Clustering aggregates the power of multiple, distributed Cisco CallManagers, enhancing the scalability and accessibility of the servers to phones, gateways, and applications. Triple server redundancy improves overall system availability. Call admission control ensures that voice quality of service (QoS) is maintained across constricted WAN links, and automatically diverts calls to alternate public switched telephone network (PSTN) routes when WAN bandwidth is not available.