Landlines have been around since March of 1876 when Alexander Graham Bell patented the first telephone. A landline telephone system, also known as plain old telephone service or (POTS), commonly handles both signaling and audio information on the same twisted pair of insulated wires.
Very rarely is our landline service disrupted, in fact it is more reliable than our cellular phones. In extreme cases like after 9/11, we can see how a landline can be easily disrupted. After 9/11 landline and cellular calls coming in or going out of New York City were disrupted. The landline and cellular networks were overloaded from the tremendous amount of calls from people outside and inside the city. After 9/11 many government agencies came to realize they needed emergency satellite communication that does not rely on landline or cellular networks.
Landline and cellular networks can also be overloaded or disrupted by hurricanes and earthquakes. After Katrina landline and cellular networks were disrupted for weeks. Fortunately satellite phones were able to provide emergency communication for people who chose to be prepared for the hurricane.
Satellite phone networks do not rely on the public phone system for calls from satellite phone to satellite phone. When landline and cellular networks are disrupted it is usually confined to a relatively small area. When a satellite phone network utilizes the public phone system it’s usually outside the area of disruption. Satellite phone calls basically go up from the satellite phone to a satellite then that call goes down to a gateway on the ground which is most likely outside the area of disruption. The call is then sent buy a T1 line or the public phone system to its call destination. The reverse is true when calling a satellite phone from a landline or cellular phone. The call goes to the gateway by a T1 line or the public phone system then is switched and sent to a satellite. The call then goes from the satellite down to the satellite phone by passing the area of disruption.
Satellite phone to satellite phone calls when using the same satellite network in the same area do not use T1 or the public phone system. When using the Iridium satellite network calls are handled completely by the satellite constellation. But this is only if calls are between two Iridium satellite phones. With the Globalstar network the gateway servicing that region of the planet handles the calls back and forth to the satellites never using the public phone system. The Globalstar constellations of satellites are basically relays that bounce the call back down to the gateway and satellite phone. Globalstar calls this “bent pipe technology”.
If a call is made from an Iridium satellite phone to a Globalstar satellite phone T1 and the public phone system must be used because calls would need to be sent on the ground from the Iridium gateway to the Globalstar gateway. This is why it is important for your emergency communication group to always use the same satellite phone provider.
Even if you have a fully functional satellite phone that does not mean it will be able to make calls to a landline or cellular phone in the area of disruption because landline and cellular networks can be non-functional in that area. This was very hard for many satellite phone users to understand during the Katrina disaster. It is also important for satellite phone users to remember that they must be outside away from tall structures and trees to receive good service. A satellite phone must have line-of-site to one of the satellites providing service to the phone to be able to complete a call.