Satellite phone is a terminal device acts like a normal mobile or cellular phone. Satellite phones unlike normal cellular phones does not connect to a tower . They connect to satellites orbiting around the earth. Satellite phone are useful in a sense that they are connected directly to the satellites and thus transmission cannot be monitored by local authorities.
Satellite cell phones can there fore be used some times by criminals but most of the time they have positive usage. For example if you are are going on a cruise ship where you have no communication device with you you can rent a satellite phone for few days and take it with you on board. If you are going to a remote place or a war zone where there is no service then again you can take satellite phones with you and can be in contact and can use them in emergency. So satellite phones are used in emergency most of the times. Internet can also be accessed via satellite phones but the bandwidth is usually slow but still it is at least you can use it.
Satellite set phones are usually costly and can cost thousands of dollars and their market price keep on varying according to the service provider quality. Satellite phones can either provide service by using Geosynchronous satellites which are satellites around 33000 kms away from earth and usually used for television channels. They appear to be stationary from earth. Some satellite phones use Low Earth orbit Satellites for their transmission. which will enable them to be used even on north and south poles and some other directions. Major companies which provide Satellite cellular phone service are Globalstar Satellite phone, Thuraya Satellite Phone, At&t Satellite Phone, Inmarsat Satellite Phone, Iridium Satellite Phone.
The cost of satellite phone service is usually around 1 dollar to 2 dollar and keeps on varying from company to company. Each provider of Satellite phone manufactures phones just for itself and you cannot switch services if you purchase a satellite phone. So you have to stick with the same company. Satellite phone service quality is different from company to company. Most of the time people will not purchase Satellite sets and will just rent them because they only need them for some time. Local cell phone networks can be destroyed by power failures and natural disasters but if you have a satellite phone you get the signal all the times. There are many companies who do the service of satellite phone rentals on temporary basis monthly , daily or yearly or on contract basis. So before purchasing or renting you must consider cost of Satellite phone, Service provider quality of services and their terms of service.
The countries where satellite phone is most ofter used are the countries with huge size and having coverage of cell phones restricted in only some areas. For the remote areas people have no other choice to used phone via satellites in case of emergencies. The countries include Australia, Canada, USA, Brazil, Argentina, Russia and China. As these countries Russia, China, America, Canada, Brazil are huge in size so the some areas are only covered by Satellite phones. Also the poles including and sea satellite phones are used widely.