How Does A Satellite Phone Work?

Satellite phones as their name suggests rely on near-earth satellites instead of fixed masts.  Satellite phone coverage is not disrupted by hills, buildings and trees blocking signals. The only limitation on a satellite phone is a clear view of the sky.

Globalstar, one of the big players in the satellite phone market, provides voice and data services to their handsets via a constellation of 48 satellites and a further four in orbit back up satellites. This permits a call to be simultaneously transmitted by several satellites to an Earth base station for routing through the land-based telephone infrastructure.

Some satellites remain in a fixed position hundreds of miles above the earth and provide a 'footprint' of coverage. Other companies, though, use orbiting satellites that travel at over 16,000 miles per hour and circle the globe in less than two hours. When a call is received by a satellite, it relays the voice or data back to earth. Depending on the satellite's position at the time, it will either provide communications for the duration of the call or pass it onto the next satellite in the chain to take over before the signal is lost.

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