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Satellite phone

A satellite telephone, satellite phone or satphone is a type of mobile phone that connects to other phones or the telephone network by radio through orbiting satellites instead of terrestrial cell sites, as cellphones do. The advantage of a satphone is that its use is not limited to areas covered by cell towers; it can be used in most or all geographic locations on the Earth's surface.
A fixed installation, such as one used aboard a ship, may include large, rugged, rack-mounted electronics, and a steerable microwave antenna on the mast that automatically tracks the overhead satellites. Smaller installations using VoIP over a two-way satellite broadband service such as BGAN or VSAT bring the costs within the reach of leisure vessel owners. Internet service satellite phones have notoriously poor reception indoors, though it may be possible to get a consistent signal near a window or in the top floor of a building if the roof is sufficiently thin. The phones have connectors for external antennas that can be installed in vehicles and buildings. The systems also allow for the use of repeaters, much like terrestrial mobile phone systems.
Some satellite phones use satellites in geostationary orbit, which appear at a fixed position in the sky. These systems can maintain near-continuous global coverage with only three or four satellites, reducing the launch costs. The satellites used for these systems are very heavy (about 5000 kg) and expensive to build and launch. The satellites sit at an altitude of 35,786 kilometres (22,236 mi); a noticeable delay is present while making a phone call or using data services due to the large distance from users. The amount of bandwidth available on these systems is substantially higher than that of the low Earth orbit (LEO) systems; all three active systems provide portable satellite Internet using laptop-sized terminals with speeds ranging from 60 to 512 kbit per second (kbps).
Two such systems, both based in the United States, started in the late 1990s, but soon went into bankruptcy after failing to gain enough subscribers to fund launch costs. They are now operated by new owners who bought the assets for a fraction of their original cost and are now both planning to launch replacement constellations supporting higher bandwidth. Data speeds for current networks are between 2200 and 9600 bit/s using a satellite handset.
All modern satellite phone networks encrypt voice traffic to prevent eavesdropping. In 2012, a team of academic security researchers reverse-engineered the two major proprietary encryption algorithms in use. One algorithm (used in GMR-1 phones) is a variant of the A5/2 algorithm used in GSM (used in common mobile phones), and both are vulnerable to cipher-text only attacks. The GMR-2 standard introduced a new encryption algorithm which the same research team also cryptanalysed successfully. Thus satellite phones are not recommended for high-security applications.
While it is possible to obtain used handsets for the Thuraya, Iridium, and Globalstar networks for approximately US$200, the newest handsets are quite expensive. The Iridium 9505A, released in 2001, sold in March 2010 for over US$1,000. Satellite phones are purpose-built for one particular network and cannot be switched to other networks. The price of handsets varies with network performance. If a satellite phone provider encounters trouble with its network, handset prices will fall, then increase once new satellites are launched. Similarly, handset prices will increase when calling rates are reduced.
Inmarsat satellite phones are issued with codes +870. In the past, additional country codes were allocated to different satellites, but the codes +871 to +874 were phased out at the end of 2008 leaving Inmarsat users with the same country code, regardless of which satellite their terminal is registered with.