How does electromagnetic wave (microwave) used in cellular mobile phones?

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Many telecommunications systems use high-frequencies radio waves called microwaves. Relays and satellites pass the signals around the world Mobile telephone networks use numerous antennas (base station) to transmit and receive signals within small areas called cells. When a caller uses a mobile phone, a microwave signal is sent to the nearest antenna, which connects the caller to the network.

Regular signals from each mobile telephone let a central computer know where to direct incoming calls for that telephone. The base station responds to the cellular phone signal by assigning the phone an available RF channel. When the RF channel is assigned, radio signals are simultaneously received and transmitted, allowing voice information to be carried between the cell phone and the base. The base station transfers the call to a switching center, where the call can be transferred to a local telephone carrier or another cell phone.

some source from:
http://www.nasa.gov/home
http://science.hq.nasa.gov/kids/imagers/ems/radio.html