Cisco Unified Communications

Introduction to Cisco Unified Communications and Cisco Unified CallManager

This chapter covers the following topics:

• An introduction to the Cisco Unified Communications strategy (formerly Cisco AVVID) and Cisco Unified CallManager technology
• An understanding of the placement of Cisco Unified CallManager in an IP telephony design
• The interaction between Cisco Unified CallManager and Cisco IP Phones
• Cisco Unified CallManager server platforms

Although IP telephony might seem like the new, emerging technology in IT environments, it has actually been around for many years. As WAN and LAN data connections became more stable and the total amount of available bandwidth increased, legacy PBX vendors rushed to add IP processing functions to their chassis-based management systems. Cisco Systems also saw the writing on the wall and in 1999 unveiled both the Cisco 7900 series IP Phones and the Cisco Architecture for Voice, Video, and Integrated Data (AVVID) strategy for the future. This was also the year that Cisco announced Cisco Unified CallManager version 2.4.

A Cisco IP telephony deployment relies on Cisco Unified CallManager for its call-processing and call-routing functions. Understanding the role that Cisco Unified CallManager plays in a converged network from a system, software, and hardware perspective is necessary to successfully install and configure Cisco Unified CallManager. This chapter discusses Cisco Unified Communications and the Cisco Unified CallManager functions, hardware requirements, software requirements, and installation and upgrade information.

Note

With the recent launch of the new Cisco Unified Communications portfolio, Cisco AVVID has become an obsolete term because it no longer accurately describes the breadth of Cisco's converged, unified communications offerings. This chapter still occasionally makes reference to Cisco AVVID in historical contexts, but for the most part uses the term Cisco Unified Communications. You might find them used interchangeably during this transition period.

Note

Cisco has recently changed the name of the Cisco CallManager product to Cisco Unified CallManager to reflect the Cisco Unified Communications campaign. For brevity, this book mainly uses the shortened name of Cisco CallManager or just CallManager.

When Microsoft announced their new .NET platform, there was a huge amount of confusion in the industry. Systems administrators did not know if they were to expect a new operating system, programming language, or company direction. The same effect happened when Cisco announced the Architecture for Voice, Video, and Integrated Data (AVVID), now known as Cisco Unified Communications. Network administrators did not understand if this was a new router type, IOS feature set, or marketing campaign. Cisco Unified Communications is not any of these things. Instead, it is a company strategy that provides the foundation for converged networks. The goal of Cisco Unified Communications is to create network equipment that has the capability to handle voice, video, and data traffic within a single network infrastructure.

Figure 1-1 shows the four standard layers of the Cisco Unified Communications voice infrastructure model: the infrastructure layer, which lays the foundation for network components; the call-processing layer, which maintains PBX-like functions; the applications layer, where applications that provide additional network functionality reside; and the client layer, where end-user devices reside.

Figure 1-1. The Cisco Unified Communications Model for Voice Networks

 

Each of the major areas of the Cisco Unified Communications architecture has a similar model focused around the technologies of voice, video, and data. The key points about the four standard layers of the voice model are as follows:

• Infrastructure layer The infrastructure carries data between all network devices and applications and consists of routers, switches, and voice gateways.
• Call-processing layer Call processing is physically independent of the infrastructure. Thus, a Cisco CallManager in Chicago can provide call control for a bearer channel in Phoenix.
• Applications layer Applications are physically independent of call-processing functions and the physical voice-processing infrastructure; that is, they can reside anywhere within the network.
• Client layer The client layer makes the voice applications available to the user, whether the end device is a Cisco IP Phone, a PC using a Cisco IP Communicator, or a PC delivering converged messaging.

At first, this might seem like just another model to commit to memory; however, understanding Cisco's design of this model allows you to make the most of your voice network. The OSI model creates a standard for communication across networks. In addition, it allows vendors to isolate network functionality and specialize in equipment working at a specific layer. Likewise, one of the huge benefits of using an IP telephony system over a PBX system is the open standards for protocols and equipment. A vendor could specialize and design devices that work only at the client layer of the Cisco Unified Communications voice model. These devices could use an open standard protocol to communicate with the Cisco CallManager at the applications layer.

Note

Because of the flexibility of the Cisco IP telephony network, many organizations have created their own custom applications for the voice network. Cisco has made a Cisco CallManager Software Development Kit (SDK) freely available to aid in the process of creating custom Extensible Markup Language (XML) applications.