If you have ever wondered how it was possible for a person to make a phone call from the top of Mount Everest, the North Pole, or out in the middle of the ocean, the answer is simply that the caller was using a satellite phone.  This type of phone looks a great deal like a cellular phone with the exception of a much larger antenna.  Satellite phones typically weigh more than a cellular phone as well.

I think I’ll let it go to voicemail…

The main difference between a satellite phone and a cellular phone is the way their signal is broadcast.  Cellular phones use a system of base stations that are placed strategically across the land.  The base stations together create a network which is capable of transmitting and receiving the signal from a cellular phone and transferring it to its destination.  Cellular phone coverage is limited to the range of the network.  If you are not close enough to a base station, you will not be able to use your cellular phone at all.

Satellite phones rely on a system of orbiting satellites, frequently called constellations, to transmit and receive signals.  Each satellite phone provider relies on their own constellation of satellites to provide coverage to their customers.  Some constellations cover the entire globe while others work specifically in one area.

There are two main types of satellites that are used for this purpose.  The first is called ‘geosynchronous service’ which involves placing satellites into orbit at an altitude of 35,000 kilometres.  Because of their high altitude, service providers are able to achieve nearly full global coverage with as few as three satellites.

You can tell by the attena…

Each one of these satellites weighs around 5,000 kilogrammes.  They are expensive to construct and expensive to launch.  This is often acceptable because a limited number of satellites are actually needed.  In most cases a geosynchronous service is much cheaper to start up than the alternative.

A major downside to geosynchronous service is lag time.  With satellites several thousand kilometres above the Earth, you can imagine that it may take some time to send and receive a signal.  In order to use a satellite phone that has geosynchronous service, you will need to point its antenna directly upwards at the orbiting satellites.  This means that a clear line of sight is needed to obtain a signal which is not always easy to find.

The alternative form of satellite coverage is called Low Earth Orbit systems, or LEO.  This type of satellite is placed into orbit at an altitude ranging from 640 to 1120 kilometres.  They orbit quickly which allows this type of service to provide excellent coverage.

It’s all about the dish and the satellites…

One downfall of an LEO system is that numerous satellites are required to obtain full global coverage.  This can lead to high start up costs and numerous satellites must be first constructed and then launched.  This type of satellite is not in geosynchronous orbit which means that several satellites are needed to provide coverage to any particular area.  As one LEO satellite moves out of range, another needs to follow right behind it in order to provide continuous coverage to the area.  A LEO satellite will typically stay in range of a particular area for a period of less than 15 minutes.

LEO satellite phone networks are great because they do not require the caller to have a direct line of sight with the satellite.  Because these satellites are placed in a much lower orbit that their geosynchronous counterparts, lag time is also diminished as well.

There are a few different ways to actually make a call with a satellite phone.  One of the most common is to place a call from your satellite phone to a landline.  When this occurs, the call is routed through the satellite network and bounced back to Earth through what is called a gateway.  This gateway will then direct the call through a landline and on to its destination.  If the satellite call was placed to a cellular phone, the gateway would have directed it through a cellular network instead.

This is not a satellite phone

If you are using your satellite phone to call someone on another satellite phone, the call is simply bounced between the necessary satellites and onto the receiver’s handset.  No landlines or cellular networks are necessary in this type of event.

Along with the different types of satellite phone networks, there are also different types of satellite phones.  One of the most popular types of satellite phones available today is the hand held variety.  This is the type that resembles the cellular phone and they are the frequent companions of adventurers and travellers.

The other form of satellite phone looks more like a traditional phone that you would use with a landline.   This type of device is known as a fixed site satellite phone.  They are great for use in buildings as their antenna can be mounted directly on the roof.  This provides the necessary line of sight while allowing the caller to remain in the building.

Tom would’ve benefited from one of these phones!

Satellite phone service is great to have in the event of an emergency. Landlines and base stations can easily be damaged in an earthquake, hurricane, or other type of accident.  When this happens, your phone coverage disappears.  Because satellite phones rely on satellites that are safe in orbit, even in the event of an emergency your phone coverage should be unaffected.
Satellite phone service certainly sounds convenient but it also comes with a hefty price tag.  You can expect to pay upwards of £1,000 just for the satellite phone, or terminal, itself.  It does not cost a lot of money to place a call using a satellite phone but it does cost a small fortune to call a satellite phone from a landline.  It is also very expensive to call between different satellite phone networks as well.

Satellite service providers offer pre-paid phone plans to their customers.  These plans can range from as little as £10 to as much as £3,500 or more.  Some service providers even offer unlimited calling plans but this is extremely rare.