Wednesday, June 20, 2012

What Are the Differences Between Cell Phones & Satellite Phones?

Satellite phones rely on a network of communication satellites for signal coverage.

Nearly anyone with a cell phone has experienced signal loss or areas where weak reception makes using cell phone a trying ordeal. For people who need instantaneous access to mobile communication in remote areas --- like deserts, jungles or the middle of the ocean --- cell phones just aren't sufficient. For these people, satellite phones offer the ability to communicate regardless of the user's geographic location.


Cell phones are essentially two-way radios, communicating with a local tower that forms a "cell" --- a region of space covered by the transmitters on that tower. A "cellular network" consists of a wide range of these cells. Problematically, though, cell phone radios are relatively short range, and expansive networks require large numbers of these towers, which may be prohibitively expensive or may require infrastructure that's not available. Satellite phones, by contrast, communicate directly with a satellite constellation orbiting the Earth. This allows them to receive a communications signal over a much wider area; if the constellation's visibility over the planet's surface is complete, a satellite phone can connect anywhere.

As a rule, satellite phone handsets tend to be larger than their cellular counterparts, and may have prominent antennas designed to improve communication with the satellite. In the early days of satellite phones, this difference was pronounced --- the first satellite phones weighed up to 16 ounces, and this bulk provided only 2 hours of talk time. Later phones, like their cellular counterparts, have grown smaller; modern satellite phones may be nearly indistinguishable from short-range cell devices. In other respects, using a satellite phone is relatively similar to using a cell phone --- newer phones support Internet connectivity, and many satellite services support "text messaging," or SMS.

Range and Applications

Although most cities and urban areas now have access to cell networks, this still represents only a fraction of the Earth's surface. Satellite phones --- which can operate anywhere --- fill a substantial gap for people like ship captains, who need to have the ability to communicate just as easily in the middle of the Pacific as in the middle of Philadelphia. Satellite phones also see widespread use in war zones and disaster areas --- places where traditional phone infrastructure might exist, but is too heavily damaged or oversaturated.


The primary downside of satellite phones is their cost --- both to acquire the phone and to use it. Satellite phone companies have to deploy their own expensive technology --- each satellite costs tens of millions of dollars --- and look to recoup this from their users. Initially, a call on the Iridium network cost $7 per minute; as it turned out, users were unwilling to pay such a high premium for global phone access, and Iridium was forced to drop their prices. At $1 a minute or more, though, satellite phones are a fallback option --- useful only when traditional landlines or cell phones don't work.


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