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

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 mobile phone, but usually 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. 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 antennae that are often installed in vehicles and buildings.

Satellite phones are usually issued with numbers in a special country calling code. For example, Inmarsat satellite phones are issued with codes +870 through +874, while Iridium satellite phones are issued with codes +881 6 and +881 7. Some satellite phones are issued with ordinary phone numbers, such as Globalstar satellite phones issued with U.S. telephone numbers.