Infrastructure Layer

At the infrastructure layer, we are building the connections between all the devices that send and receive data, voice, and video. These include Layer 2 and 3 switches, routers, and voice gateways. Voice gateways are among the most important components because they provide the connection to the PSTN or other network carriers. One of the critical functions (and one that is unfortunately often underemphasized in many deployments) is quality of service, or QoS. QoS provides service guarantees to various types of network traffic, in particular voice and video traffic. Without QoS, you can experience poor call quality or even failed calls. Infrastructure design and deployment is literally the foundation of the system; if any weaknesses exist here, they will manifest as system failures or unreliability. It is very important to build a solid and correct foundation. The goal is to achieve 99.999% uptime; achieving that goal takes careful attention and good design.


Call Processing Layer

The call processing layer is chiefly about the call agents. A call agent is not a person; it is an application that looks at the signaling traffic from devices that place and receive calls, and it determines what to do with the call. A Unified IP Phone sends a packet to the call agent when you lift the receiver; the call agent instructs the phone to play a dial tone. When you begin dialing a number to call, the call agent receives the digits and tries to find a match for the number in its dial plan. If the destination number is a phone that it controls, it tells the called device to ring. During the call, the call agent also sets up other services, such as Hold, Call Park, Transfer, Conference, and so on. The call agent also instructs the phones to tear down the call when one party hangs up. The call agent usually keeps detailed records of each call made; these are commonly used for billing purposes or troubleshooting.

Cisco provides several options for call agents, matched to the size and requirements of the customer:

• The Cisco Smart Business Communications System is designed for small businesses with up to 48 users. The system runs on the Cisco Unified Communications 500 Series for Small Business devices.

• Cisco Unified Communications Manager Express serves up to 240 users and runs on the Integrated Services Router platforms.

• Cisco Unified Communications Manager Business Edition handles up to 500 users and runs as a standalone installation on a 7800-series Media Convergence server.

• Cisco Unified Communications Manager can handle 30,000 or more users and runs on clusters of 7800-series Media Convergence servers.

Smart Business Communications System


The Smart Business Communications System is a group of specially designed, integrated devices that can provide highquality routing, firewall, intrusion prevention, Power over Ethernet, wireless, and many WAN and PSTN connectivity options. It is essentially a solution-in-a-box, with a simple web-based interface that is largely plug and play. The Unified Communications 500 Series devices are small and inexpensive, providing the kind of connectivity options small businesses need to allow them to take advantage of Unified Communications with a good ROI. The SBCS is expandable using 500-series switches, and the call agent software can support up to 48 phones. Voice mail and Auto-Attendant functions are provided by the integrated Cisco Unity Express application.


Unified Communication Manager Express


Cisco Unified Communication Manager Express is a software feature that can run on the ISR-series router platforms, including the 800, 1800, 2800, 3800, and 7200-series platforms. The call agent application is embedded with the Cisco IOS software and is configured either from the command line or a Web-based interface. Unified CM Express is a fullfeatured call agent that is cost-effective, reliable, and scalable and integrates with both Service Provider connections and Unified Communications Manager clusters. With support for both H.323 and SIP protocols, site-to-site connections are possible in a variety of environments. The Unified CM Express system can be set up either as a PBX or a Key switch system, providing customers with a familiar experience that suits their operating environment.


Unified Communications Manager, Business Edition

Unified Communications Manager, Business Edition is a standalone installation of the Unified CM application and Cisco Unity Connection, coresident in a single MCS 7800-series appliance. This system can support up to 500 users in a single site or multisite centralized deployment and can be migrated to a full CM cluster if growth necessitates it. Unified CM Business Edition provides medium-size businesses with advanced features such as Mobility (a.k.a. Single Number Reach), Do Not Disturb, Intercom Whisper, and Audible Message Waiting Indication, as well as speech recognition and integrated messaging. Because Unified CM Business Edition uses the same call agent software as a full cluster deployment of Unified CM, it supports full integration with the other Unified Communications applications, such as Unified Presence, Unified Personal Communicator, MeetingPlace Express, Contact Center Express, and so on.


Unified Communications Manager

The full version of Unified Communications Manager is an enterprise-class, fully scalable, redundant, and robust distributed packet-telephony application. Scalable to 30,000 users per cluster, with the capability to form intercluster connections, it can support a global unified communications system for hundreds of thousands of endpoints. Unified CM versions prior to 5.x are Windows based, whereas versions 5.x and 6.x are Linux-based appliances.