Breathe New Life Into Payphones with Asterisk

Payphones used to be found on just about every street corner. They were a convenience, now replaced by the ubiquitous mobile phone. These machines were the stomping grounds for many early computer hackers, and as a result hold a place in hacker history. If you’ve ever wanted to re-live the good ol’ days, [hharte’s] project might be for you.

[hharte] has been working to make these old payphones useful again with some custom hardware and software. The project intends to be an interface between a payphone and an Asterisk PBX system. On the hardware side, the controller board is capable of switching various high voltage signals required for coin-line signaling. The controller uses a Teensy microcontroller to detect the hook status as well as to control the relays. The current firmware features are very basic, but functional.

[hharte] also wrote a custom AGI script for Asterisk. This script allows Asterisk to detect the 1700hz and 2200hz tones transmitted when coins are placed into the machine. The script is also in an early stage, but it will prompt for money and then place the call once 25 cents has been deposited. All of the schematics and code can be found on the project’s github page.

[Thanks mies]

21 thoughts on “Breathe New Life Into Payphones with Asterisk

  1. if you dont want your payphone to be redboxed you could tap directly to the totalizer to the switch that sent the signal to the tone generator (witch is a small board with 2 large tuning coils (like in some older phones) and some other parts) and read the timing from the switch.

    1. You can find payphones online, usually modified for home use but hey, it shouldn’t be that hard to get it back to payphone spec. As for red boxing, hey if I had one (outside of course) and caught someone red boxing it I’ed yell at him “I salute you, you magnificent bastard!”

      1. The payphones show there are incompatible with this project. They are internally computer controlled. As a matter of fact, if you hooked up one of those phones to this project, it would probably blow up from the high voltage.

  2. This is interesting. I have an active payphone and use a small SIP adapter that connects to my network. I make a huge profit per call but not very many people need a payphone anymore. It has been awhile but I remember I had to program the phone to dial differently and it doesn’t have 911 access.

  3. I had good times with COCOTS even 15 years ago. Currently I have a PBX setup for Choose Your Own Adventure action with two storylines to choose from. They are for the youngsters in the family, but I already have requests for more adventures by summer roadtrip time from the family. The youngstas like being able to use the phone (like an adult) and the adults like being able to think silently for 10 second bursts lol. It has been done many times over the years, but I daresay my inspiration came from a blurb a couple of years ago on somethingawful.com. The longest part is coming up with the story arc and interweaving in a meaningful way.

  4. If I had been sneaker with my apparently illegal salvage, I could have made off with a free payphone at the dump. I guess the city can own garbage, and that it’s not considered salvage but theft. :(

  5. I had a payphone hooked up in my front yard that was programmed to take coins but return them when the call was finished. Had issues with code enforcement but finally got the to leave me alone. Believe it or not one person used it to call for road service because he broke down and had a dead cell phone. The phone was hooked up to my channel bank and went through Asterisk, Unfortunately a drunk driver crashed into it before destroying my fence and hitting the tree. The phone and pedestal is destroyed and I am looking around for another, but keep losing pay phones to those trashing them out. Hope to get one soon and re-install, this time behind the tree,

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