Mobile Switching Centre-(MSC):

• The MSC co-ordinates the activities of all the base stations and connects the entire cellular system to the PSTN.

• A typical MSC handles 100,000 cellular subscribers and 5,000 simultaneous conversations at a time, and accommodates all billing and system maintenance functions as well.

• Communication between the BS and mobiles is defined by a standard Common Air Interface (CAI) that specifies four different channels.

Base Station-BS

• The base station is installed for every cell. It communicates with all the mobile stations existing in its cell. The BS Communicates with the mobile switching center (MSC).