Satellite phones are the only choice for reporters posting a breaking news story from the mountains of Afghanistan and almost anyone who is trying to stay in touch with their office or family during a Caribbean cruise. Consumers are more and more seeking out satellite phones because they enjoy the great outdoors (less urbanized areas) where many times cell phones do not work.

Consumers do rock climbing and mountaineering. They take adventure holidays and do 4 x 4 off-roading and offshore sailing. The military, emergency services, forestry, mining, heavy construction businesses choose satellite phones to make communication possible in remote working conditions and on aircrafts and vehicles. Satellite phones are the answer when it is absolutely, positively necessary to have a phone in the far reaches of the world.

A satellite phone is a telephone-like device that sends radio signals direct to a satellite then down to a land earth station from where the call can be directed to the Public Switched Telephone Network (PSTN) as well as a cellular network. The reverse is also true. Any land-line or cellular network can call satellite phones. The Gateway processes and takes care of the switching of the calls rather than the satellite network. This allows telephone usage even when a person is literally in the "middle of no where" and too far away from a cell tower for a cellular phone. When a user calls another compatible satellite phone, the call is transmitted up to the satellites and then down to the ground station then transmitted back up to the satellites then down to the receiving satellite phone. This is the ultimate secure calling because the encryption is handled at the ground station because the call never goes to a land-line or PSTN.

The most popular hand held satellite telephones use Low Earth Orbiting (LEO) satellites. When the user turns on the satellite phone the signal goes up to any number of satellites in a compatible constellation where it is then registered with the constellation.

The major telecommunication satellite constellations are: Globalstar, Inmarsat, and Iridium. As an example Globalstar has 48 satellites and Iridium has 66 that orbit the earth. Satellite phone systems are expensive to build and far less competitive than conventional mobile systems, so there are only a few providers from which to choose. Satellite phones are used in remote locations where normal "wired" telephones or cellular coverage is not available or in otherwise civilized locations when these communication infrastructures have been temporarily or permanently rendered inoperable (due to civil disturbance or earthquake for example).

There is no single phone that works everywhere except a satellite phone and although they are hand-held they don't work indoors. Satellite phones use incredible technology to provide global coverage at reasonably low costs. However, there are a few basic laws of physics that they cannot break.

Satellite phones need a clear line of sight view of the satellite. Performance can also be affected by poor weather and use is generally restricted to outdoors (though they will sometimes work through glass or canvas). For Iridium, this means the phone (or at least the phone's antenna) must be outside with a reasonably unobstructed view of most of the sky. Iridium phones use a non-directional antenna - which means it does not have to be pointed in any particular direction.

For Inmarsat, which uses geostationary satellites, the phone's antenna must actually point directly at the satellite with an unobstructed view. The antenna must be outside. The set up procedure is very simple and can be accomplished in seconds with ease. Both types of satellite phones can be supplied with long antenna cable extensions to allow the hand set to be operated inside a building, and for vehicle or maritime use, the Inmarsat phone can be supplied with an optional automatic antenna, which points itself towards the satellite. Great strides have been made in making these phones increasingly portable, though briefcase models are still available and just about all of them need an oversized antenna.

Another law of physics that must be respected by satellite phones is that bandwidth is limited. Satellite phones share the limited resources of the satellite amongst users in many different countries. The engineers have developed amazing systems that allow narrow-band carriers to be used to carry voice signals. However, this technology is not capable of delivering high bandwidth data-Internet access is certainly possible, but it is slow. For higher bandwidth options, a large antenna version of the Inmarsat system is available-Inmarsat M4.