What is a satellite phone?
A satellite phone (sat phone) is a portable voice and data terminal that communicates directly with a satellite in orbit rather than with terrestrial cellular base stations. Satellite phones provide communication capability in locations entirely beyond cellular coverage: deep ocean, polar regions, mountain ranges, deserts, and conflict zones where terrestrial infrastructure is destroyed or absent. They are used by maritime crew, expedition teams, military personnel, journalists, and emergency responders.
Key networks and devices
Iridium: The only truly global sat phone network (pole to pole, all oceans), using 66 LEO satellites. Iridium Extreme 9575 handsets provide voice, SMS, and low-speed data (2.4 kbps) anywhere on Earth. Inmarsat IsatPhone Pro: L-band GEO-based satellite phone covering mid-latitudes (approximately 70°N/S); good battery life and ruggedisation. No true polar coverage. Globalstar: Regional coverage (not polar, limited ocean) via 24 LEO satellites; clearer voice quality in coverage area but significant geographic gaps. Thuraya (UAE, Yahsat affiliate): L-band GEO phone service covering Europe, Africa, Middle East, and Asia — used extensively in humanitarian operations.
Versus Direct-to-Device
Traditional satellite phones require dedicated hardware distinct from standard smartphones. The emerging Direct-to-Device (D2D) category — SpaceX Starlink Direct to Cell, AST SpaceMobile — is working to eliminate the need for separate sat phone hardware, enabling standard smartphones to connect to satellite networks. However, current D2D offerings provide much lower bandwidth than dedicated sat phones, which remain the preferred tool for voice-primary applications in the most remote environments.