I used a 1970's era "Mobile Telephone" only once, but talked on them thousands of times. I worked for THE phone company and I was one of the operators that helped connect the car radios to land lines.
The mobile telephones had up to SIX frequencies that you could choose. That meant that 6 people in a 100 square mile area could talk at the same time! Those phones could not dial directly, so people like I sat there all day long waiting for a light to light up.
RE; pagers... The first pagers were associated with an answering service. They were a simple radio receiver that listened for specific tones assigned to that pager. They were restricted to a small geographic area.
With the first pagers, you called the person's number, an answering service operator took your name and number and message, then they sent a signal to the pager. All the pager did was "Beep-Beep-Beep", and thus was nicknamed a "beeper". The person with the pager found a pay phone and called the answering service to get your message. The big advantage of this system was that the answering service could page you ONLY when the message was urgent.
Then came the "digital pagers" that would display a phone number (keyed in by the caller). Automated answering devices streamlined the process so that your boss and co-workers could page you at any time of the day or night without any filters, and you called them back directly.
We used computers with modems to call these these devices and pass cryptic 12 digit codes whenever we had a problem with the computers or networks at work. Each of us had a wallet card with the meaning for all the codes. This allowed a small group of 3 people to maintain a hundred computers in 20 sites without needing a person watching the print-outs all day and night.
The big problem with pagers was that they were one way. The beeper had no way to tell the paging system that the message was received. This made a great excuse when you wanted to ignore someone.
It was the late 80's that we got Satellite based pagers. Mine covered All of the western US. I don't know how it replied back, but there was a feedback to acknowledge the signal. They were also alphanumeric, so you could use a computer program to send a text message. Eventually Email to pager gateways were established, eliminating the need for a special program and dedicated phone line to send text messages.
As recently as the Clinton (Bill) presidency the secret service was using alpha pagers to coordinate their activities. It turns out that their signal was not encrypted in any way, and that a home computer + radio shack scanner was all you needed to intercept and decode the messages. They did use code names for the first family, but it was easy enough to figure out who was where and what routes they were taking.
I much prefer using my smart phone.
Dan
