A satellite phone or satphone is a mobile phone that communicates directly with orbiting satellites. Depending on the architecture of a particular system, coverage may include the entire planet, or only specific regions.

satellite phone (Inmarsat)The mobile equipment, also known as a terminal or earth station, varies widely. A satellite phone handset has a size and weight comparable to that of a late 1980s or early 1990s cell phone, but with a large retractable antenna. These are popular on expeditions into remote areas where terrestrial cellular service is unavailable.

A fixed installation, such as used shipboard, may include large, rugged, rack-mounted electronics, and a steerable microwave antenna on the mast that automatically tracks the overhead satellites.

Low Earth orbit

LEO telephones utilizes LEO (low Earth orbit) satellite technology. The advantages include providing worldwide wireless coverage with no gaps. All satellite phones tend to be LEOs. LEO satellites orbit the earth at high speed, low altitude orbits with an orbital time of 70–90 minutes, an altitude of 400–700 miles, and provide coverage cells. Since the satellites are not geosynchronous, they must fly complete orbits and thus further guarantee complete coverage over every area by at least one satellite at all times. Blimps are being considered as satellites.

List of satellite phones

Global providers

Inmarsat is a long-respected "industrial-grade" provider, with voice and fax equipment installed in most sea-going vessels and many aircraft. They also provide ISDN services, famously used for news reporters' videophones during the 2003 Invasion of Iraq.

Globalstar and Iridium are recent entries to the market, having undergone financial restructuring since the dot-com collapse of the late 20th century. Most users access these systems using handheld phones for voice and low-speed data.

Regional providers

MSat provides telephone, low-speed data, and voice dispatch service to North America, Central America, and the Caribbean. The bulky equipment is similar to that used by Inmarsat. MSat users are assigned a number in the North American Numbering Plan.

Thuraya has a coverage area focusing on northern and central Africa and the Middle East. Handsets used for the service are also compatible with GSM networks, and contain GPS receivers.

Teledesic was a proposed system supported by a partnership of many large players in the industry including Microsoft, Motorola, Nextel, Boeing, Matra Marconi Space and McCaw Cellular Communications. Motorola is the primary contractor. There were to be 288 satellites at an altitude of less than 800 miles and a data access of 64 megabits per second. It is particularly significant in its huge potential for broadband internet. As of November 2004 Teledesic has not gathered the required funding for satellite launches to begin.