Since we’re on a roll talking about telephone technology let’s branch out.

The most obscure phone device that more people have seen than used is the acoustic coupler. Did you see the movies WarGames or TRON (boy talk about dated references eh)? These days, these are probably the most likely place people will see an Acoustic coupler in action. Back when you had to lease your phone from the Ma Bell and when most people still had rotary dial phones (instead of Touch Tone based phone systems) someone figured out a bright idea for how to connect two computers together over a phone line.

The acoustic coupler was a device that most commonly plugged into the serial port on your computer and would convert the data sent to it into audio tones. It would then pulse those tones over the phone line where the recipient computer would record the tones and turn then back into data to be processed (in many ways it analogous to data storage via audio cassette tape on early computers, but that’s a whole other subject). You would dial the phone manually and tell the person on the other end to put their receiver on their coupler and set their computer to receive. Then you put your handset on your coupler. Once the computers were connected you would start data transmission.

After the AT&T/Bell break up I mentioned previously, people eventually had the ability to plug any device other than a Bell telephone into the phone network. From there you saw modems that you just plugged the phone line directly into. These modems would also be able to issue the dialing tones to initiate a call and would be able to monitor the line for a ring in order to provide an unsupervised answer (this led to the dawn of home computer run Bulletin Board Systems). The last progression was to move the modem directly into the computer as a board that plugged into a slot. Less and less people are using modems now with the spread of broadband internet services. Although in very remote locations where the only communication is a old style telephone landlines, some people still use modern acoustic couplers that run off the USB port. As cell phone tethering becomes more prevalent though this too shall likely pass.

Another soon to be lost piece of one common phone technology are RF based Beepers and Pagers and eventually their cellular technology based cousins. Before everyone had cellphones, someone working in a job that had to be on call might carry a beeper. Initially beepers were tied to an operator, and then to a voice-mail system. Someone would call you and leave a message. Your beeper would buzz/beep. You would call your operator or voice-mail system and retrieve your message.

The first major upgrade of these featured a small display on the beeper that would display the phone number of the caller.

Following that, pagers got to the point where the display would show any number that the caller punched in so you could send a message that included other numbers that represented agreed to code number systems which allowed you to get the gist without having to call the voice mail.

The last generation I’ve seen most commonly used supported texting/SMS services like you would have on your cell phone.

Beepers used to be expensive and common in nearly all professions but from personal experience for IT workers in the 90’s having to carry a beeper for their employer was more of a curse than a benefit. It may have been this way in other industries as well for all I know. The curse being that you had no excuse for missing that alert at 2am when the server actually crashed.

One reality scenario here was:

1. Your employer thought their systems were so important that they needed a 24/7 baby sitter.
2. But they were too cheep to actually pay staff to sit in a data center around the clock to monitor for problems.
3. So now you get lovely false alarm beeps waking you at 3am when the random Windows server reboots unexpectedly.

Additionally, for a number of years having a beeper (just like early cell phones) was used as a status symbol for the rich and famous to help make sure they looked important even if they never used it.

Some good extra reading if you’re up to it:

http://www.corp.att.com/history/
http://www.corp.att.com/attlabs/reputation/timeline/

Or, jump back to Part 1 or Part 2