The world has come a long way since the early days of the 'Sputnik'! Satellite systems are now providing both voice and data communication for parts of the world where there is little or no land or cell phone provision. Using satellite telephones help you to keep in contact when you are in the air or out at sea. They also help us to track and remain in contact with adventurers who test the limits of endurance and skill. We are able to follow their routes, talk to them and receive images and movies from wherever they may be and we can be instantly ready to help them when things don't go quite according to the plan.

How does it work then? The satellite phone transmits a signal, via an antenna to an orbiting satellite in a network of satellites then back to a ground station and a standard land based phone network. Sounds good doesn't it? However, the line of sight signal path between the satellite telephone and satellite must not be obstructed. Even bad weather can sometimes be a problem. In general, reception is much better outdoors but if you are on a boat at sea or in a plane in the air then an external antenna might be needed.

Right now there are five major satellite phone service providers. Global Star and Iridium are still the largest. They offer an array of options for both businesses and the average person in the street. Iridium is perhaps the best known of them all for a variety of reasons. The company uses a network of 66 operational low-earth-orbit satellites and they have an additional 13 spare satellites too. The satellites are in orbits roughly 485 miles above the surface of the Earth.

They supply to an extensive variety of markets which include construction, mining, government, leisure and maritime. They also provide equipment to the military and to rescue and disaster relief organisations. Companies tend to sell their services through a collection of service partners, value-added resellers and manufacturers.

Wherever there is a need for reliable, go-anywhere communications you will see satellite phones being used. The military make extensive use of them, as do airlines and shipping. They can also be invaluable in disaster areas where there it's likely that land based communications have been disrupted by the disaster or never existed in the first place. Satellite phones can be tracked too. This can come in handy when guiding aircraft into isolated areas quickly.

Trucks that travel close to the Alaskan pipeline are being fitted with satellite phones in a bid to combat terrorism. If a truck gets hijacked then the authorities are notified instantly using the satellite network. Using the same satellite phone, the hijacked truck can be disabled before the terrorist has a chance to use it as a weapon.

As a method of communication satellite telephones remain a very expensive option. It is more expensive than most cell phone calls. As the technology improves and becomes more widely used, the prices should begin to drop. At the moment Iridium claim that the cost of a satellite phone call is similar to the cost of an international roaming call. To improve public perception and possibly build the consumer market the industry is fund raising in Washington state to provide satellite phones and airtime free of charge to US National Guard soldiers serving in Iraq.

Steve is a software engineer and webmaster of Satellite Phone Keep up with what's new in Satellite phones at http://www.satellite-phone.thecatcollar.com