A satellite phone is a telephone that communicates via artificial satellites. Because it does not rely on terrestrial base stations, it can make calls in areas beyond mobile phone coverage, such as mountainous terrain, open sea, deserts, and polar regions. When terrestrial communications infrastructure is destroyed during a disaster, satellite phones continue to function, earning them the designation of "last-resort communication."
Three main satellite phone services are available in Japan. Iridium uses 66 low-earth-orbit (LEO) satellites at approximately 780 km altitude to cover nearly the entire globe, including the poles. Thuraya uses geostationary (GEO) satellites at approximately 36,000 km altitude, primarily covering Asia, the Middle East, and Africa. Inmarsat also uses GEO satellites and has strengths in maritime communications. LEO satellites are closer to Earth, so latency is about 20-40 ms, enabling natural conversation. GEO satellites have higher altitude, resulting in latency of about 540 ms, which creates a noticeable delay in conversation.
Satellite phone adoption is accelerating as part of BCP (Business Continuity Planning) for municipalities and corporations. During the Great East Japan Earthquake, terrestrial communications infrastructure was devastated across wide areas, and satellite phones were the only means of communication in some regions. Learning from this, satellite phone deployment has expanded to municipal disaster response centers, hospitals, power companies, gas companies, and other lifeline operators. Handset prices range from 100,000 to 300,000 yen, and call charges are about 100-300 yen per minute - more expensive than regular mobile phones - but there is no alternative for ensuring communication during disasters.
In recent years, civilian use of satellite communications has expanded rapidly. Apple's iPhone 14 and later models include satellite-based Emergency SOS, enabling emergency calls even outside mobile coverage. SpaceX's Starlink has launched its Direct to Cell service, with plans to enable text messaging and voice calls via satellite on regular smartphones. Together with emergency call numbers, check Emergency Phone Number Guide to review communication options during disasters.