A satellite phone or satphone is a mobile phone that sends and receives calls using satellites rather than landlines or cellular broadcasting towers. This phone only requires a clear line of sight to the sky, so it can complete calls from anywhere. One can operate in the middle of the Sahara desert, at the top of Mount Everest, or from a clearing deep within a South African jungle. It is an indispensable tool for remote excursions of all kinds, and provides solid communication on the seas and in the air.
A disadvantage of a satellite phone is a noticeable delay in conversations. The signal must first travel to the satellite, then to an earthbound gateway before being routed to the receiver. The receiver's response will follow the same path in reverse, taking equally long to reach the caller. Satellite minutes are also more expensive than cellular minutes.
These drawbacks are often irrelevant, however, when considering the function that such a phone serves. It can create a link to civilization from places where no other link is available. It also allows people in remote places, as in the case of researchers, adventurers, and those in the military, to stay in touch with loved ones, and it can provide backup communication in disasters when cellular towers or landlines might not be functional.
People who only need to use a satellite phone on rare occasions can rent one rather than buy it. Most phones require both weekly rental fees plus a separate charge for talk time, which can be much more expensive than minutes on a regular cell phone. Those who decide to buy a phone outright will likely be required to sign a contract with a satellite network, although prepaid cards may be purchased in some cases. Minutes are typically less expensive with a contract than when renting or buying prepaid, but are still more expensive than cellular minutes.
These phones range in price according to network coverage areas. Phones that can literally send and receive calls from anywhere in the world are quite expensive, and even basic models that have a more limited range are often several times more expensive than a regular cell phone. Because satphones are so expensive, they are often purchased used.
Some satellite networks have partnered with cellular GSM networks to provide Internet service and email on their phones in addition to offering GSM roaming. This allows a customer who lives or works at the fringes of a GSM zone to use those networks when possible, and make satellite calls only when necessary. Such built-in flexibility is ideal for military, disaster or relief contractors, rural ranchers, local boaters, or anyone who requires or desires guaranteed regional or global coverage.