10/09/2022
Satellite Telephone

To function, your cellphone needs to be in the vicinity of a transceiver. But there's another type of mobile phone that doesn't need to be near any towers, because it communicates directly with satellites in orbit above the Earth. There is more than one provider of satellite telephone service, but the industry leader is Iridium. The Iridium system consists of an interconnected network of 66 satellites that provide global service. That is, from the South Pole to the Amazon River basin, your Iridium phone will let you communicate with anyone around the world.
The Hidden Network
Each of the telephone types described above has its own particular method of transmitting and receiving signals, but behind each of them is an interconnected global network. Signals from cellphones, landlines, possibly even satellite phones, all end up travelling through the same network: a complex and sophisticated combination of wires, fiber optics, and microwave and radio transmitters. The network is just full of communication devices that you'll never see: routers, optical-to-electronic converters, add/drop multiplexers and many more. The key to global interconnectivity is that each different style of telephone can tap into the network, which allows billions of people to reach each other.
Using the Hidden Network
Computer communications — email, Twitter, Facebook, web searching — use the same kind of network. In fact, the networks are converging and merging into an interconnected monolith. That's one reason why the phone company now offers television service, the cable company offers telephone service, and your Internet provider wants you to buy television and telephone from them. Any device that can tap into that network — your cellphone, your tablet, your laptop — can conceivably offer all the services available through that network.
Augmentative and Alternative Communication Devices
The previous sections outlined various options for telecommunications, reach
