Payphone Conversion

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With the demise of the pay phone, they are becoming more and more accessible for a good price. Its funny to think that once upon a time, you couldn’t walk 2 blocks without seeing them, now finding one when you need it is next to impossible. In 2008 there were 95,000 pay phones in Canada, in 2012 that number had dropped to 70,000 (quote from CRTC website).

It is unfortunate, but in a past, I watched over 8 tons of pay phones come in to a scrap yard. I couldn't touch any of it...

Well, being a pay phone enthusiast I had to do something. Make them more usable. This article will be my attempt to do that. Because I do not want to step on the toes of the current owners of the IP, I will not be attempting to hack the main board inside the phone, but rather how to repurpose the generic parts that are inside the phone that make a payphone nothing more than a fancy looking analog phone. We will also explore the display. VFD displays are a generic part that you can buy from adafruit or solarbotics or a thousand other places. We will also explore the coin validator, but again it is no different than any of the other coin validators that exist for sale on those sites. What sets this payphone apart is its unique main board, with voice synthesis and simulated dial tone and sorry its beyond the scope of this article. I think you would need a working payphone to be able to get that figured out anyhow.

The information I will be showing here is information you can gather with a multimeter, Logic analyzer and a disabled pay phone. Just power on the phone causes it to do a health check on the internal components, this is the source of 90% of this information.

Most pay phones require the use of a pay phone provider to have a server that will allow communications. It is not worth trying to simulate the server. I don't think it would be possible unless you had the co-operation of the provider.

The Goal:

First off, I need to set your expectations, I am not here to provide you with a way to build your own payphone to earn money. This is just meant for educational purposes. I cant tell you how long I wondered how all the internals of the payphone worked!! I want to do this conversion so others can learn from all the hard work I put in to it.

Because Nortel pay phones depend on a mainframe to control them, it does not make sense to work with the electronics inside. But we will cover it from a high level, just for good measure. We will be talking about gutting the phone, and replacing all the control electronics.

-Install an analog phone inside the pay phone to provide dial tone

-Install an Arduino to control the VFD (2x20 Noritake CU20026SCPB-T23A) display

-Map the keypad to a conventional analog phone keypad.

-Setup a VoIP Analog Telephone Adapter inside the phone, just in case you have VoIP and want to make your phone portable (Cast iron top, bottom, Aluminum face plate, and like 4 layers of steel inside the cash box, maybe,,, not so portable)

-Review the communications protocol for the coin validator. I set mine up so my kids could use it as a piggy bank, the VFD would display current balance in the vault.

Note:

I have seen so many people buy Nortel pay phones thinking they can just plug it in and away it goes. This is dishonest of the reseller not to mention that these phones in particular are hard coded on the eprom to prevent them from working without a provider. Please take caution, if you want to just plug it in and go, it DOESNT work that way, in fact unless you got it from Nortel with unlocked software (who knows why it existed, but an article I found called it Demo Code?? maybe for trade shows?) your shit out of luck. If you follow this article to bring a phone back to life, you can do all sorts of things.

I can not stress enough, this information is only for educational purposes and should not be used to actually modify a payphone without the permission of the current owner of the IP.

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