[Paul_1966]

Hi all,

There were multiple reasons which led to the adoption of 999 by the British G.P.O. in the 1930's.  One of the major considerations was to use a number which involved minimum disruption to the existing numbering schemes in use. 

London used a step-by-step director system in which the first three digits of the seven-digit number (dialed as letters at that time) determined the exchange the call was to be routed to.  Except for the special case of dialing 0 for operator, all calls thus required a minimum of three digits before the equipment could decide how to connect the call, so a three-digit emergency number was needed.  As the digit 9 corresponds to the letters WXY, from which no useful names could be made up, the code 999 was vacant.  The same was true for the other major cities which used the director system, such as Glasgow (which was to get 999 service soon after London).

Elsewhere in the country, no subscriber numbers started with 9, because the 9 level on first selectors was used to access various services (directory enquiries, telegrams, etc.).   Moreover, from many rural and village exchanges, a first digit of 9 already connected to the parent exchange to allow subscribers to dial directly to that larger place.   As emergency calls needed to go to such places where the operators were located, the initial 9 of 999 already routed the call to the parent exchange without the need for any modifications at those smaller exchanges. 

The other very important factor which affected the choice was to allow for payphone users to call without needing to deposit any coins.   The prepayment phones which were standard at that time worked by preventing the dial from operating until the correct minimum fee for a local call had been deposited (2d. in the 1930's).  However, extra contacts on the dial opened when it was rotated right round to the zero position in order to permit callers to dial the operator without coins.  It was relatively easy to modify the dials to allow for both 9 and 0 to be dialed, thus allowing coin-free calls to 999 as well. 

As far as the adoption of 911 in the U.S.A. is concerned, this happened much later (the first place to get 911 service was Haleyville, Alabama in 1968).   Codes such as 211, 411, 611, and so on were already well established, having been in use for several decades by that time in many parts of the country.  911 was part of this reserved service-code sequence so fitted the need well.  Another consideration at the time for using 911 rather than some other spare n11 code was to make it easier to implement in areas using step-by-step switching equipment, since the 9 level was more likely to be unused for subscriber numbers.   More complications arose with 411, 611 etc. in step-by-step systems, which is why many of these had traditionally used codes such as 113 for information and 114 for repair service instead of 411 and 611.

[Geezer (OP)]

Great answer Paul! Many thanks.

[Paul_1966]

You're welcome.  And to pick up on a few other comments:

All true, but I think 911 came into use in the US prior to new fangled push button phones.

DTMF (TouchTone) dialing started to appear in the U.S. in the early/mid 1960's, but only in a few places, so certainly wasn't in widespread use when the decision to adopt 911 was made.

I assume that 911 had never been assigned an area code prior to its adoption as an emergency number, thus quicker routing.

None of the n11 numbers have ever been used as area codes, as they were already in use in many places as service codes (information, long distance etc.) when the area-code plan was drawn up in the late 1940's. 

The original plan was that the middle digit of an area code would be 0 or 1 (which continued to be true until the 1990's).  The reason for that was to allow equipment to distinguish between area codes and a number within one's own area from the second digit dialed.  Seven-digit numbers within each area code with the first two dialed as letters was to be the norm (as in, for example, the famous PEnnsylvania 6-5000 number in New York).    As there are no letters on the 0 or 1 digits, that meant that if the second digit dialed was 0 or 1, then the caller must be dialing an area code and the equipment knew to wait for ten digits in total.   

Because the n11 numbers were already in use as service codes, however, they were excluded from being assigned as area codes, and the equipment "knew" that if both second and third digits were a 1, then it wasn't an area code after all.

I've been told (possibly by Dave's dad) that it used to be possible to make "trunk" calls at local rates (which covered the local exchange plus nearest neighbours) by dialling through to the neighbouring exchange, then (because you appeared to be a local call) the next one over, then the next one, and so forth, thereby bypassing the transition to (much more expensive) national calls.

Yes, in the old British network that was possible in some places.  Long before STD (Subscriber Trunk Dialling) came along, there were local dialing codes to permit calling nearby exchanges without the assistance of an operator.  Typically you dialed 9 (as noted above) to reach the parent exchange in town, and subscribers there dialed codes such as 81, 82, 83, etc. to reach the outlying places.  Calling from one rural exchange to another which was parented on the same town exchange often involved dialing 981, 982 etc., the stages of the call progress there being fairly obvious.  There were numerous other variations to cater for local needs, and subscribers were issued with booklets containing all the local dialing codes for places they could dial direct (officially).   Steps were usually taken to prevent calling beyond the official local area, but it wasn't always easy and sometimes it could still be done with the right sequence of codes.    The local dialing codes finally vanished from the system during the 1980's.

Not that I ever tried it myself you understand, but I seem to remember it was possible to dial numbers in the UK from a call box by tapping the handset cradle to simulate the pulses produced by the rotary dialer. Consequently, it was possible to avoid the tiresome inconvenience of actually inserting money into the device.

Yes, with the old prepayment boxes (the ones which had the "A" and "B" buttons on them) that was possible.   As noted above, the dial didn't work (except for 9 and 0) until the local call fee had been deposited.  In normal operation, making that deposit also shorted out the transmitter in the handset so that you couldn't talk to your distant party until you pressed button "A" to drop the coins into the box and restore the contacts (pressing button "B" also restored everything, but returned the coins and disconnected the line for a few seconds to release the connection). 

So if you didn't make any initial deposit, the dial wouldn't work, but the transmitter was still active.  Pulsing out the number on the hookswitch would thus give a free call.

That ceased to be possible with the postpayment coinphones which gradually came into use during the 1960's, as all the coin control was done by relay sets at the exchange and both the dial and the transmitter were active all the time. 

[CliffordK]

Interesting note about phones.

As far as Geezer's suggestion...  I don't think it worked for international calls from Italy.

I remember getting a pocket full of "Gettone" phone tokens.
I'd fill the phone up with as many Gettone as it would take, perhaps 10 or so.
Then once the call began, I'd continue to stuff them into the phone as fast as I could possibly do it.  The calls would normally last a couple of minutes before I just couldn't keep up with the coins.

[Paul_1966]

As far as Geezer's suggestion...  I don't think it worked for international calls from Italy.

I'm not familiar with the arrangements used in Italy, but as far as the old British A/B coinphones were concerned, pulsing out the number on the hookswitch to get a free call worked only for local calls, since all long-distance calls (and international, if you had a pocket big enough to hold the coins!) were placed via the operator who would then listen to the bell and gong signals as you dropped coins into the phone, just as with the old three-slot coinphones in America.    Although you could dial beyond the local area with this method by using the local routing codes as described, if you knew what to dial and there were routes which weren't barred in your particular area, as described above. 

Because of the way the coin mechanism worked, as described previously, it was actually possible to call TIM (the speaking clock) or any of the other prerecorded services such as weather for free from a coinphone by actually using the dial, so long as you had the coins to make the initial deposit.   You could hear the distant party answer before pressing button "A" to drop your coins into the box, but could not speak to him - Something which clearly wasn't needed when just listening to a recorded announcement!   So you just deposited the local call fee, dialed the number as normal, listened to the announcement, and then pressed button "B" to get your money back when finished.  So coinphone users could call those services for free while regular residential customers were charged for them.

All of these "tricks" became impossible with the postpayment phones which were introduced for STD and which could be used to dial long-distance as well as local.