Satellite Phone
A Satellite phone, communicates through SIM card (Subscriber Identity Module) with a landline, cellular, or other satellite phones irrespective of natural calamities or disasters, unlike Cell Phones(connect with tower), a satellite phone works normally anywhere in the world if the user is not talking from the inside of buildings or any kind of structure that blocks their view of the horizon. Satellite phones generally have special international numbers with Direct Inward Dial capability. A global network could be accessed through Inmarsat and Iridium, with some models offering GPS tracking. Both avail constellation of geostationary orbit satellites that are 23,000 miles from earth, circling the Equator. They have a latitude limitation of approximately 70 degrees north of the equator to 70 degrees south of the equator.
An omnidirectional or directional antenna in the mobile phone is used for both transmitting and receiving signals. Satellite phones generally require line-of-sight with the sky to receive a signal for service.
Low-earth orbit satellite networks consist of groups — or “constellations” — of satellites that rapidly move around the earth — much faster than the actual rotational speed of the planet. These series of low-earth orbit satellite constellations work together to rapidly move clear signals between communication points. High-earth orbit satellite networks usually consist of a set of three satellites that are moving in time with the natural rotation of the earth. This allows them to stay in position and provide highly consistent coverage to areas that are relatively flat and open. However, when in rugged, rough, and mountainous terrain, it can be difficult, and in some cases impossible, to get a signal [https://www.outfittersatellite.com/Satellite-Phone-Basics_b_229.html]
Where there are no landline or cellular telephone networks, or in areas where existing networks are damaged or overloaded during a natural disaster (e.g., severe weather or earthquake) or a man-made incident, including potential chemical, biological, radiological, nuclear, or explosive events. Satellite mobile phones can help maintain command and control functions during an emergency when existing communications networks are not functioning[ Technote -Homeland security]
Restrictions on the use of Satellite Phone in India by the Department of Telecommunication apart from Inmarsat GSPS (or Global Satellite Phone Service)
“Satellite phones are permitted:-
(i) With specific permission/ NOC from Department of Telecommunications, Government of India; or
(ii) As provisioned by M/s BSNL in accordance with license granted to M/s BSNL for provision and operation of satellite based service using Gateway installed in India.”[https://dot.gov.in/]
Inmarsat IsatPhone 2 units cost $519.00 in USA