How is a satellite phone different from a cellular phone?

What Is a Satellite Phone?

A satellite phone or satphone is a mobile phone that sends and receives calls using satellites rather than landlines or cellular broadcasting towers. A satellite phone only requires a clear line of sight to the sky. The advantage of a satellite phone is that it can complete calls from anywhere. A satellite phone 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.

However, these drawbacks are irrelevant when considering the function that a satellite phoneserves. It can create a link to civilization from places where no other link is available. It also allows loved ones to stay in touch, as in the case of researchers, adventurers and those in the military, and it can provide backup communication in disasters when cellular towers or landlines might not be functional.

The three main satellite networks at present are Iridium, Globalstar and Thuraya. Iridium uses low orbiting satellites that minimize conversational delays, but more importantly, it is the only current satellite network that provides coverage over the entire earth, including the oceans. Competitor Globalstar covers about 80% of the earth's landmasses, excluding northern and southern polar regions, while Thuraya covers parts of India, Asia, Africa, the entire Middle East and Europe.

For those who only wish to use a satellite phone on rare occasions, one can rent rather than buy. Rental fees start at about US$40 per week, but this does not include talk time, which can run as high as $1.75 per minute. If buying a satellite phone outright, a contract is necessary with a satellite network, or prepaid cards may be purchased. Minutes are less expensive with a contract than when renting or buying prepaid, but are still more expensive than cellular minutes.

Satellite phones range in price according to network coverage areas. Iridium phones are more expensive because they can make calls from anywhere in the world. One current entry-level Iridium satellite phone sells for US$1,275, while other network phones start out at about half that price, and can be found for less. 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 through satellite phones in addition to offering GSM roaming. This allows a satellitephone customer that lives or works at the fringes of a GSM zone to utilize GSM networks when possible, and satellite calls 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.

How is a satellite phone different from a cellular phone?

Satellite and cellular phones are wireless devices. They almost look alike but the way they work is totally different. A cellular phone functions on the basis of cells, and hence are called cell phones. The whole network area is divided into small areas and an antenna is installed in each area. These are also called towers. When a cellular phone is moving, it enters from one cell to another. When it crosses the border of one cell, the phone sends a signal to the MTSO (Mobile Telephone Switching Office). With the help of control channel the database of the MTSO relocates the phone in a new cell or area. Satellite phones use Low Earth Orbiting (LEO) satellites. When a satellite phone is turned on, a signal goes up to any number of satellites of a group the phone is registered with. When a person makes a call from the handset, a signal goes to the nearest orbiting satellite. The satellite connects to the gateway or ground station. Then the gateway takes the call to the destination.