Class of Service Overview

Class of Service (CoS) is a collection of calling permissions and restrictions that you assign to individual users or groups of users. (The terms calling permissions and calling restrictions are used interchangeably in this chapter.)

Note

CoS as it applies to telephony networks holds a completely different meaning than its application in quality of service (QoS). CoS in telephony means the implementation of calling restrictions, whereas CoS in data networking means the application of a data link layer marking in a data frame.

Examples of class-of-service permissions are as follows:

• One class of users can place toll calls during normal business hours, but not at other times.
• Lobby phone users can dial the local emergency numbers and campus extensions, but cannot dial local, long-distance, or international numbers.
• Receptionists can dial anywhere within the company and all local area codes, but cannot dial long-distance or international numbers.
• Executives can call anywhere except 900 area codes.

Cisco CallManager uses partitions, calling search spaces, and time-of-day routing to implement class-of-service restrictions.