Author Topic: 12 hole dial. German test set.  (Read 2543 times)

Offline dsk

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12 hole dial. German test set.
« on: March 09, 2011, 02:52:26 AM »
Never seen this before.

http://tinyurl.com/45kpu4s

dsk

I have even got a regular New York number :-) 646 570 1796

Offline Owain

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Re: 12 hole dial. German test set.
« Reply #1 on: March 09, 2011, 01:21:20 PM »
Never seen this before.

http://tinyurl.com/45kpu4s

dsk

Ah, duodecimal dialling.  :o

Offline Phonesrfun

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Re: 12 hole dial. German test set.
« Reply #2 on: March 09, 2011, 01:43:47 PM »
Unless someone is good at German, if someone can capture the instruction photo that is in the e-bay auction, and somehow convert it to text, we can run it through a translator and get a close English translation.  Unfortunately, the native German version is way beyond my rusty German skill set.

I have a feeling that the 12 digits were probably a way to select different levels or otherwise set the test set up for different modes of testing.  I doubt this dial was used to outpulse to a phone line.

-Bill G

Offline dsk

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Re: 12 hole dial. German test set.
« Reply #3 on: March 09, 2011, 02:53:48 PM »
Hard to understand for me too ;D

What I understand is it is able to generate different frequencies and adjust the signal level.
The 16kHz is especially mentioned, this was (is?) superimposed on the line for those who pays for a metering device to calculate costs.   I can remember it was used on pay phones too, to activate coin collection.

I did not understand the text about the dial.

dsk

I have even got a regular New York number :-) 646 570 1796

Offline teka-bb

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Re: 12 hole dial. German test set.
« Reply #4 on: March 09, 2011, 05:21:01 PM »
These dials actually give 11, 12 or 13 pulses when dialing a 10, 11 or 12. With these special dials it is possible to make connections with e.g. trunk lines between CO's and other circuits or test lines within a certain type of CO. A normal subscriber obviously can't make those connections because they only have a 10 digit dial.

I have several dials like this one including  examples mounted on test tools / boxes.
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Online HarrySmith

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Re: 12 hole dial. German test set.
« Reply #5 on: March 09, 2011, 05:41:33 PM »
I would like to get one of these dials and put it in a 500 just to see the look on peoples faces when they see the extra numbers ;D
Harry Smith
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Offline GG

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Re: 12 hole dial. German test set.
« Reply #6 on: March 10, 2011, 08:50:59 AM »


It won't fit on a 500 but it should fit on any standard German phone, e.g. W48, 611, etc.

Here's what'up with the 16kHz tone:

German payphones (and in a number of other countries) and private lines' "meters," worked with "meter pulses."   I'm going to describe this using American coinage and fictitious calling rates because that'll still be understandable. 

At home you could have a little box next to your phone with something in it that looks like an odometer.  It shows how many units you're using when you're on the phone.  Let's say each unit is worth 5-cents.  Now you make a local call which is charged at 5-cents for every 5-minutes.  OK, so once every 5 minutes, the CO switch sends a little 16 kHz pulse down your line.  You don't hear it but the meter does, and it clicks forward another unit, and you see you've just spent five cents. 

Now you make a long distance call.  Let's say the cost of that call is 15-cents per minute.  Now at the start of each minute, the CO sends three pulses of 16 kHz tone down the line, so your meter clicks over three units at the start of every minute.  This let you know how much you were spending, in real time, so you wouldn't get a surprise when the phone bill came. 

Now let's go to a payphone in one of those countries in the 60s or 70s. 

The front of the payphone has one or more sloping channels inside, below the coin slots, that are visible through a thick glass or plastic panel on the front.  You insert your coins into the slot(s) to dial any call other than Fire/Police/EMT, and the coins rest in the channels where you can see them.  Let's say you put in 50-cents in 10-cent pieces, and the rate for a long distance call is 20 cents per minute. 

Now when the called party answers, the CO sends four 16-kHz pulses for 20-cents.  The payphone interprets the signals as signifying 20-cents, and knows there are coins in the 10-cent piece channel, so it tries to "eat" two coins.  Since there are five coins there to start from, you're looking at the front of the phone and see that two of your 10-cent coins have just dropped out of the channel and you have three left.   

Now at the beginning of the second minute, the same thing happens again.  And the phone knows there is only one coin left so it beeps at you (and maybe a light flashes) to let you know to put more coins in.  You put in three more 10-cent coins, and now you see that four coins are in the channel. 

At the beginning of the third minute, the CO sends four more 16K tones and eats two more coins.  Now you have two coins left in the channel.  But you wrap up your call and hang up before the end of the third minute.  The phone returns your two remaining coins. 

It's a very clever and cool system that I never had the chance to see in person.  A few of the countries it was used in were Germany, Switzerland, Denmark, presumably Sweden, and also in Spain. 

It would have been excellent to have in the US except that it might have become a target for vandalism, a problem that is much less in the countries where it was used.

There is an older variant of this involving a 60-Hz AC signal sent from one side of the phone line to ground.  With that version, you hear the 60-Hz signal, which is mildly obnoxious, but with the 16kHz version you don't hear it because the telephone receiver can't reproduce sounds that are so high in pitch. 

If you have any KTAS phones from Denmark, you may find one of those meters built right into the phone, under a little chromed rectangular frame on the top surface of the phone. 

In England, the GPO offered something similar for homes and offices, but it looked more like a clockface.  Probably France did something like that as well.

However neither England nor France had those types of payphones.  There was a time when France used "POA" (Pay On Answer) payphones that were externally very similar to those in England during the 60s - 70s, and so far as I know they were operated by meter pulses as well (darn it, I have three UK payphones here, and the tech info, I should know more about this).  However the UK and France payphones used an audible tone ("pay tones" or "rapid pips") to alert callers that they needed to stuff more coins into the slot to continue the conversation. 

The closest we got to that in the USA was "dial tone first" payphones typically AE, where you would have a coin ready to drop through the slot the moment your called party answered.  Line polarity on Strowger switches would reverse upon answer, causing a relay in the payphone to short out the transmitter until you dropped a coin in the slot.  I'm not certain how they handled it after the first three minutes, and I've used those when I was a kid so I should have remembered it.   For long distance calls, the operator would ask for the deposit of however-much it was, before letting you speak to the called party. 

Offline dsk

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Re: 12 hole dial. German test set.
« Reply #7 on: March 11, 2011, 04:03:44 AM »
The 16 kHz system was used here too.
It could bee fooled, when calling from a pay phone, the pay phone in some systems had a similar feedback to tell the coin was collected, but when the younger users was screaming in high pitch tone ore using a silent dog whistle the system accepted this.

When I served we had a 16kHz system on the payphone, but by just hooking up a regular phone on the line, we called for free.  :D This had obviously no feedback when the coins was collected.

Quite handy when the daily pay was about equal to the cost of 2 beers ;)

dsk
« Last Edit: March 11, 2011, 04:44:16 AM by d_s_k »

I have even got a regular New York number :-) 646 570 1796

Offline GG

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Re: 12 hole dial. German test set.
« Reply #8 on: March 11, 2011, 12:27:37 PM »


DSK, interesting stories there.

In the US there were also numerous ways to beat the charges on payphones.  No doubt we could devote an entire column to various historic methods, and the vulnerabilities they exposed. 

The system using meter pulses could have been improved by requiring a keep-alive tone sent from the phone back to the CO, but of course hackers (phone phreaks) would learn to simulate that tone also. 

Cat and mouse, 'round and 'round. 

Offline Owain

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Re: 12 hole dial. German test set.
« Reply #9 on: March 15, 2011, 01:49:45 PM »
These dials actually give 11, 12 or 13 pulses when dialing a 10, 11 or 12. With these special dials it is possible to make connections with e.g. trunk lines between CO's and other circuits or test lines within a certain type of CO. A normal subscriber obviously can't make those connections because they only have a 10 digit dial.

I have several dials like this one including  examples mounted on test tools / boxes.

Here's a British Tester 355 which has additional ABCDEF buttons (which is two over the usual DTMF 4x4 grid).

Ebay Link 


Offline luns

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Re: 12 hole dial. German test set.
« Reply #10 on: January 12, 2016, 08:54:43 PM »
These dials actually give 11, 12 or 13 pulses when dialing a 10, 11 or 12.

First thought to cross my mind was "So *THAT* is how you call Pizza Pizza!". I'll elaborate if nobody else recognizes the sentiment.

I've toyed with the thought of pairing something like a Rotaphone together with such a dial like this to provide * and #.

Offline Jack Ryan

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Re: 12 hole dial. German test set.
« Reply #11 on: January 12, 2016, 09:20:02 PM »
These dials actually give 11, 12 or 13 pulses when dialing a 10, 11 or 12.

First thought to cross my mind was "So *THAT* is how you call Pizza Pizza!". I'll elaborate if nobody else recognizes the sentiment.

I've toyed with the thought of pairing something like a Rotaphone together with such a dial like this to provide * and #.

I haven't seen this thread before. 11, 12 or 13 pulses? so if you dial one you get 2 pulses? Sounds unlikely but who knows?

The discussion about 16kHz coin collection is a bit strange. There was only ever one collect signal at a time - if the rate increased for a circuit, the collect signal was sent more often.

The whistle trick is only likely to have worked on trunk (long distance) calls. Mostly a particular duration and frequency was required - perhaps a caller could whistle that...

There was an older system that applied 50Hz (not 60) across the line wires and ground (seen as common mode noise by the telephone).

Jack