When cellular phones started becoming popular in the 90s most people were
buying them for emergency usage only. Now cellular phones have become more
of a standard. Everyone has one and may have discontinued their landline
service because it is an unneeded expense.
Everyone has been in an area where their cellular phone does not have a
signal which can be frustrating. There are many areas in the U.S. where
there is no cellular coverage. A cellular phone is basically an advanced
radio that must rely on cell towers close buy to receive a signal. No cell
towers close by means no signal. The basic way cellular phones work is as
you travel it receives a signal from a tower. The electronic serial number
(ESN) is registered with the cellular network establishing a connection with
that cellular provider. As you travel you will move out of coverage of that
cell tower then if there is another cell tower you come in coverage range
with, there is a soft hand off to that second cell tower not disrupting your
service. When you make a call from a cellular phone the call goes to the
cell tower to a landline then either to another cellular network or
landline. The reverse is true when calling a cellular phone from another
cellular phone or landline.
But what happens if cellular service is disrupted or overloaded. After 9/11
we can see how vulnerable we can be. After the twin towers were hit
cellular and landline networks in New York were either disrupted or
overloaded. Cellular and landline calls coming in and out were very
difficult to make. After 9/11 many government agencies realized they must
have emergency backup communication that does not rely on cellular or
landline services.
Cellular and landline service are also disrupted by hurricanes. After
hurricane Katrina cellular and landline communication was disrupted for
weeks. Satellite phones played a key role in providing reliable
communication where all cellular and landline networks were disrupted.
Satellite phone networks work when cellular networks are disrupted because
satellite networks do not need to rely on the public phone system.
Satellite phone calls basically go up to a satellite then down to a gateway
that most likely will be out of the area of disaster. The call is then sent
to its call destination which could be a landline or cellular network. The
reverse is true when calling a satellite phone from a landline or cellular
phone the call goes to the gateway then up to the satellite where it is
relayed down to the satellite phone.
Satellite phone to satellite phone calls work differently when using the
same satellite network. Calls are either handled completely by the
satellite constellation when using the Iridium service never using a gateway
or the public phone service. With the Globalstar network the gateway
servicing the area handles the calls back and forth to the satellites never
using the public phone system. This is why it is important for your
emergency communication group to always use the same satellite phone
provider.
Keep in mind even if you are using a fully functional satellite phone you
will not be able to call a cellular or landline phone in an area where the
cellular and landline service has been disrupted. This was very hard for
many users to understand during the Katrina disaster. It is also important
for a satellite phone user to be outside away from large structures and
trees. A satellite phone user must have line-of-site to one of the
satellites providing service to the phone.