GSM Key entities

( Part of Henrik Kaare Poulsen's GSM pages )

In order to understand how a cellular phone system works, let us first have a look at the key entities that are involved in making a phone call:

• cellular phone
• radio station
• network
• correspondent

The cellular phone is of couse the first key entity. The cellular phone is used by the user to make or receive a call.

When making a call, the cellular phone makes a radio connection to the nearest radio station. When receiving a call, the neares radio station makes a connection to the cellular phone.

The radio station is a part of the network. The network consists of transmission links, exchanges (also called switches) and is responsible for routing the call to the correspondent. First, the call is routed through a cellular network, but ultimatly most cellular calls are routed throught the normal telephone system as well.

The correspondent may be using a normal telephone, or another cellular phone.

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	GSM Cellular Radio Telephony Overview of the GSM system. Including description of related systems and technologies. Buy it from Amazon.com
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