Art Project - Searching for a BT Payphone

[petenickless]

Hello there,

I'm working with a charity on a project which will use the nostalgia of a BT red phonebox to elicit oral histories of an ex-mining town in Nottinghamshire.

I'm trying to get hold of a series 500 or 600 BT payphone - CT24/25 - (the styling of this series is reminiscent of the era we're looking to collect stories about).

I've contacted BT directly and X2 (the company that seem to resell the actual red BT phone boxes) but neither are able to give me any solid link to where I might be able to get hold of one. I presume there are lots of these sat somewhere? We have a budget to cover the costs of purchasing the unit.

I was wondering if anyone on this forum might have any leads I can follow (or indeed a unit they might be willing to sell)?

Any help would be massively appreciated,

Thanks so much,

Pete

[McMurdo]

Have you tried the guys at the old tech museum in Ramsgate, they seem pretty well connected, no pun intended.

museum@thismuseumisnotobsolete.com

[newlite4]

You could contact Stockyard Prop Hire

https://www.prophire-backdrophire.com/product-category/props/telephones/payphones/

They have a wide range of BT and GPO payphones for hire.
Neil

[IOWPhoneGuy]

Hmm, you are asking for one of the most iconic and sought after "modern" British Payphones, the CT24/25. Part of me would love to help you but I can't spare any. I also shudder to think what being used for an art project might ential.

X2Connect are your best bet. I know this as I visited them, in search of parts, a couple of months ago. They don't have any CT24/25, or even the follow up model, the CT34, as such, but what they do have is cosmetically restored CT54s, and possibly some CT44s, made up with earlier keypads etc, which look like the earlier models. They are not allowed by BT to sell complete or working phones, they have to be cosmetic only. They charge £250 plus VAT for one, and they don't have a cashbox.

Your next best bet is to to buy one on something like eBay. They come up form time to time, say once or twice a year - they are rare after all - and are likely to be considerably more expensive than X2Connect's cosmetic "show" models.

Mine, a full CT25 renters set, a CT24-alike from Jersey and a BT refurbed CT34, are working, or nearly so. They have all "escaped" by being "collected" at some point and found their way to collectors. As with pretty much all "heritage" telephones in the UK, they were owned by GPO and later BT and in theory so should not be in private hands, but they are. So, no, there are not loads out there laying around. The vast majority were reclaimed by BT, stripped and skipped. Relatively few CT24 and even fewer CT25 have survived the chop and found their way into private hands.

So, they are out there but hard to find and generally expensive to buy.

[Robsradio]

I’ve always wanted one of the old payphones that you would have the 2p or 10p poised and waiting for the beep, beep , beep answer tone, I bet these are unobtainable now.
Good to see a fellow IoW resident here

[IOWPhoneGuy]

Originally Posted by Robsradio

I’ve always wanted one of the old payphones that you would have the 2p or 10p poised and waiting for the beep, beep , beep answer tone, I bet these are unobtainable now.
Good to see a fellow IoW resident here

You'd loose that bet! The POA (Pay on Answer/PIPs) phones are rather more available than the CTs (Coin Telephones) that replaced them. I have a renter's set, with 5p, 10p 700 coinbox and 741 phone, a somewhat tatty but should soon be working stand alone 2p, 10p 700 coinbox and unmatched 711 phone and a complete 5p, 10p 735 red "hospital" portable phone. I don't have either of the kiosk/phone box version, the 705 and Armoured 705. The armoured type is now scarce and most examples have had a very hard life and are battered/rusted/burnt or all three :-( However, for all that, they are surprising (to me at least) popular and sought after.

I might be perusaded to let go of the "tatty" 2p, 10p 700 as in the second photo but its in bits at the moment: the coin mechanism not fitted.

[Graham G3ZVT]

A couple of payphone anecdotes.

At infants school in about 1959 the school's office phone was an extension to an A/B coinbox in the corridor, so making a call required the assistance of a pupil who would, upon command, deposit the necessary four pennies.

In the eighties I encountered a similar arrangement in a private house (not an "HMO")
This time it was a POA coinbox, and an extension upstairs, with stamping on the floor to signal when annother coin was to be inserted. The occasion was a funeral.

[IOWPhoneGuy]

The POA boxes required a special line, which had a C&FC (Call and Fee Check) unit at the exchange. The phone itself, or phone section in a 705 or 735 was normal and did not jave a special dial. For these yes, you probably would have had to so something with money to get an extension to work.

All the above means that today, with no C&FC infrastructure remaining, its hard to get a POA set fuly working - even the pips came from the exchange, and the line piolarity had to be reversed to unlock the coin slots. It is easy enough to rig them so that you can put in coins, but you won't get any pips.

The AB set up was different, however. The line was ordinary, without any special equipment at the exchange. The phone, generally a 238, was closely coupled to the AB box and used a special dial such as a dial 11, 33, 20, 22, or 23. Extensions on AB sets had no need to be special in any way and operated on the ordinary line like ordinary phones, with no need to put money in the box, unless using the phone directly associated with it. In thousands of B&Bs up and down the country, the landlady had her private phone connected to the same line as an AB renter's set, typically in the hall. The arrangement was that the subscriber, the renter of the set, the landlady and so on, had the key to the cash box of a renter's set and kept the money put in to the AB box. As long as the phone was used reasonably well, they got a profit out of renting the set.

An AB set will work on today's phone lines/VoiP/Hub without modification as all it requires is an ordinary line.

In 1980 the new microprocessor controlled payphone, starting with the CT22 came in and the system changed again. These used a nearly ordinary line but with an SPM (Subscriber Pulse Metering) unit at the exchange. This was simpler than the C&FC equipment, and were a re-use of an earlier system to provide subscribers with call metering/cost indication. SPM infrastructure no longer exists either. So while it is possible to run CT22s, 24, 25 and 34s on many of today's analogue phone connections, they will not count down credit as they cannot get any metering pulses. Later models, the CT44 and CT54 which is still in service, though in ever dwindling numbers, had internal reatime clocks and did not need SPM pulses and so could operate on ordinary, unmodified lines.

[Graham G3ZVT]

Things I remember about those more modern payphones.
The line was invariably configured for LD only, I understand that was to thwart a known fraud vulnerability. The phone did switch to DTMF after the call was answered, but some of the early so called "Blue Payphones" incomprehensibly didn't have # or * keys.

When dialling the BT Chargecard service, after the 144 was outpulsed, the phone would mute for a while but you could still faintly hear a "handshake" that didn't occur on a normal line.
First a long tone (from the distant end?)
then the payphone would respond with a longish DTMF sequence (no doubt its unique ID). Only then would the IVR ask "Please enter your account number and PIN."

I can't remember exactly when, but long after I thought POA phones were completely obsolete, I saw a row of them still in use on a University campus somewhere.

If there was a prize for the world's most uninspiring payphone design, it has to be these!

[IOWPhoneGuy]

Interesting stuff

The original "Blue Payphone" was the CT22 of 1980. There were two versions which looked very similar on the outside but were very different internally.

The trial and very early production, as in late 1980, version was the CT22A. This had a LED display for credit and white on blue instruction label. Internally they were Intel 4040-powered. They were made in Switzerland by Autelca and were a variant of their model AZ33. I have one, made in September 1980 and serial numbered 209. They were configured by a simple links on a DIL header. As far as I can tell they did no reporting and were LD only.

The vast majority, several tens of thosands, were CT22Bs however. The CT22B was made in the UK by a joint venture, AGITELCO, between Autelca of Switzerland and AGI here in the UK. They looked very similar to the CT22As but had LCD displays and blue on stainless instruction labels. Internally, however, they were very different from the CT22As. They were powered by the CDP1802 microprocessor and had configurations in battery-backed RAM downloaded from the Tester 297 (I beleive later known as the 297A, though I have not confirmed this). These phones almost certainly made report calls. The reports were made by MF tones. I have not yet had a CT22B in my hands to confirm this, but I do have a CT22A.

I say all this to point out that the CT22B did many of the things the CT24/25 & 34 later did and the processor technology and probably the firmware were similar, at least functiionally. The tester was reused for the CT24/25, 34 and other payphones including the Cardhone 1A, going through updates, first to the 297C and later, probably in 1995 to support PhONE Day, the 297E. It appears the changes were new firmware and a new front panel legend. The tester hardware appears not to have been changed much, if at all.

Interestingly, at least to a firmware developer like me, the code of the tester 297, while running on the same processor as the phones, was clearly written by different hands from that of the CT24/25/ & 34. That's not surprising as the tester was developed by AGI to support the joint venture CT22B phones. The later CT24 et al were Plessey Telecoms products. I need to get my hands on some CT22B firmware to make more sense of this.

The configuration of LD/MF dialling on the CT24/25 & 34 was by a link. Of the three CT34 boards I have access to, one is configured for LD and two for MF. So its pretty certain that some 34s, if only in their latter years, ran with MF dialling in service. It appears that they always did reporting via MF tones, though I have yet to find exactly where in the firmware that happens.

I did not know they had the capability of validating card services. I shall look for that in the code. And yes, each phone was allocated and configured with its own unique CTI (Coin Telephone Identification number). CTI were key to reporting, of course, but no doubt could have been used for other purposes.

As far as I am aware, only the very earliest CT24s had ten button keypads - essentially prototype and possibly early production examples. I have never seen one. The vast majority had twelve button keypads. They also had blue handsets. The blue handsets, at least, apparently survived into full production. I have some BT maintenance documentation that suggests they were still in serivce in 1986 but by then black handsets were also in use.

Incidentally, the firmware and hardware of CT24/25 and 34 supported an extra column, allowing the use of upto 16 keys. The support ends at the keypad itself, with the wire for the extra column being folded back and covered with a sleeve. It appears only with some variants of the CT44 were extra keys/buttons actually fitted.

Another thing that's important to bear in mind is that later models, the CT44 and 54 did many things differently. These are the models with dot matrix LCDs. They did not need the Tester 297 as they could display arbitrary text and so configuration was done via on-screen menus. They also had on-board modems and so did not need to use MF tone based reporting. I understand at least the CT54s used ASCII reporting via the modem. They had internal realtime clocks and so did not need SPM pulses. They also had DTMF receivers/decoders, though exactly what they used them for, I don't know.

As far as I am awre, the CT22A & B were the original "Blue Payphone" and only the CT24 & 34 were the "Blue Payphone 2". Both the CT24 and 34 were both also known as the Payphone 600, wihile the renter's version, the CT25, was the Payphone 500.

As to the these phones being uninspiring I have a different take. The CT24 and its later follow-ups, had a simple, robust design: a rectangular box with only those bits it needed, the essence of payphone. It was successful enough to become iconic - and be a "payphone" to many people - and to have had a very long life, from 1982 to today, well over forty years of active life. Uninspiring, maybe, but clearly successful. I like them!

All the CT24-based models, the CT24/25/34/44 & 54 share the case case and look essentially the same at a casual glance. They can easily be confused. The CT22A and B also looked the same as each other but were operationally very different.

Originally Posted by Graham G3ZVT

Things I remember about those more modern payphones.
The line was invariably configured for LD only, I understand that was to thwart a known fraud vulnerability. The phone did switch to DTMF after the call was answered, but some of the early so called "Blue Payphones" incomprehensibly didn't have # or * keys.

When dialling the BT Chargecard service, after the 144 was outpulsed, the phone would mute for a while but you could still faintly hear a "handshake" that didn't occur on a normal line.
First a long tone (from the distant end?)
then the payphone would respond with a longish DTMF sequence (no doubt its unique ID). Only then would the IVR ask "Please enter your account number and PIN."

I can't remember exactly when, but long after I thought POA phones were completely obsolete, I saw a row of them still in use on a University campus somewhere.

If there was a prize for the world's most uninspiring payphone design, it has to be these!

[Cobaltblue]

As the original poster has not come back and this thread has drifted somewhat I will close the thread.

If the petenickless comes back to visit he can post an actual wanted post.

Cheers

Mike T