999/911 (emergency calls) and how they work.

[Ace_777]

I was just wondering.

How are 999 (U.K) and 911 (U.S) (whichever one you can explain) are routed ?

Do these calls get priority? How can the emergency services triangulate our position if we are using a cellphone? How does the emergency telephone system work ?!

I've always been fascinated how technology comes together to help mankind. I find it interesting. Yes, I am weird.

[Sir_Crashalot]

As far as I know there is no priority system in telephonesystems. 999, 911, or the European 112 are just that; telephone numbers. They are directed to the nearest local emergencyroom which has it's own switchboard to recieve more than one call at a time. Cell phones are very easy to trace. Every cellphone is in constant connection with the nearest antenna. These antennas service a certain area and when you leave that area the next one takes over. That way it is easy to tell in which area a cellphone is. Since these antannas overlap eachothers area it is also possible to pinpoint the cellphone within a few meters depending on the signalstrenght (how far or how close you are to an antenna).

Crash

[Ace_777]

oooooo Neat !

Thanks for the swift reply.

[Stormtropper]

All cell phone (now days) have a built in GPS chip too, if I remember correctly.

...but on to my question, who's brilliant idea was it to set the emergency number to 999? It's one of the longest numbers to dial on a pulse phone...just imagine trying to wait for that thing to get going when someone is trying to stab you to death...

[Akula.]

All cell phone (now days) have a built in GPS chip too, if I remember correctly.

...but on to my question, who's brilliant idea was it to set the emergency number to 999? It's one of the longest numbers to dial on a pulse phone...just imagine trying to wait for that thing to get going when someone is trying to stab you to death...

Not all phones have GPS. A few of them do, and in the next few years I can see satnav phones becoming more popular, but not all of them.

And I can see how irritating the pulse phone would be... "Uhm, excuse me, could you stop stabbing for a second? im trying to make a phone call, here!"  :D

[Sir_Crashalot]

Pulse phones are those things we used to have a long time ago? With those discs with holes in it? How long since you saw (or even used) a thing like that? Even then in the time we had pulse telephones we didn't have those short emergency numbers (here in Holland at least). Every city had it's own emergencynumber. Most of the time it was the phonenumber of the police office. Later we got the 06-11 phonenumber but that lastest only a few years. 112 is now the European standard (exception is the UK with 999).

Crash

[Hagar]

...but on to my question, who's brilliant idea was it to set the emergency number to 999? It's one of the longest numbers to dial on a pulse phone...just imagine trying to wait for that thing to get going when someone is trying to stab you to death...

I believe 999 was chosen as it's easy to remember yet difficult to dial by mistake on the old GPO telephones.

[Stormtropper]

Acutally, I used one 2 weeks ago. I know the US "911" was introduced before 1970, long before tone-dial phones...and I'm guessing the Brits beat us by atleast 20 or 30 years on that (like everything else*...).

I always thought that was the reason Hagar, but isn't "911" just as difficult to misdial as "999"? ...and I'm guessing it takes a good 2 or 3 seconds to dial "911" than "999".

*Everything unimportant, but strangly, an essential part of our every day lives.

[ozzy72]

Welllllllll thank goodness for Wikipedia!
http://en.wikipedia.org/wiki/999_%28eme ... _number%29
And for the American version (and lots more details);
http://en.wikipedia.org/wiki/9-1-1

[Hagar]

Acutally, I used one 2 weeks ago. I know the US "911" was introduced before 1970, long before tone-dial phones...and I'm guessing the Brits beat us by atleast 20 or 30 years on that (like everything else*...).

I always thought that was the reason Hagar, but isn't "911" just as difficult to misdial as "999"? ...and I'm guessing it takes a good 2 or 3 seconds to dial "911" than "999".

*Everything unimportant, but strangly, an essential part of our every day lives.

I just checked & 999 was introduced in the UK in 1937. Very few people had their own phone & cell phones had never been thought of. Most ordinary people used public telephones.
A couple of years ago some bright spark decided to change a system that had worked perfectly for decades & there are now various numbers used for different emergency services in different parts of the country. If I was ever faced with an emergency I would now have no idea which number to dial.

PS. I see Mark beat me to it. This is the relevant bit.

The 999 service was introduced on 30 June 1937 in the London area. 999 was chosen because of the need for the code to be able to be dialled from A/B button public telephones. The telephone dial (GPO Dial No 11) used with these coinboxes allowed the digit '0' to be dialled without inserting any money, and it was very easy to adapt the dial to dial '9' without inserting money. All other digits from 2 to 8 were in use somewhere in the UK as the initial digits for subscribers' telephone numbers and hence could not easily be used. Had any other digits been used, other digits between that one and the already free '0' would also have been able to be dialled free of charge. No other telephone numbers existed using combinations of the digits '9' and '0' (other than one in Woolwich) therefore there would be no unauthorised 'free' calls. Thus the easy conversion of coinbox dial was the deciding factor and the fact that 999 was not used anywhere, other than for accessing the occasional 'position 9' of an Engineering Test Desk in the telephone exchange.

[ozzy72]

I can't believe I was faster than you Doug! The student becomes the master

[Mushroom_Farmer]

[quote]I can't believe I was faster than you Doug! The student becomes the master

[61_OTU]

Mark and Doug have hit the nail on the head as to why it was 999.

As for how calls are routed....

999 calls are relayed to a BT operator services centre handling 999 calls. The 999 calls take priority in the call centre queue, so once dialled they are the next answered call in the centre, taking priority over any other calls routed to the centre. The BT operator answers the call with a script "Emergency, which service?" and depending on the repsonse of the caller the operator selects the relevant choice, Police, Fire or Ambulance.

The operators terminal determines from the callers telephone number the relevant geographical area, and gives the BT operator a choice of the appropriate geographical emergency control room contact numbers. So if the call comes from an 0121 area code, then the terminal offers choices of West Midlands Police, Fire or Ambulance services. The BT operator just has to select the correct service, and connect the call.

Once the call is connected the BT operator advises the name of the BT centre they are working from and the calling line number of the person who dialled 999. The emergency services control staff then take charge of the call and the BT operator 'slots' the call, leaving it on their screen but out of the way, enabling them to continue taking calls. Once the caller and emergency service have completed the call then the BT operator clears the call down. They retain it on their screen in this way in case the emergency services require additional information at the end of the call.

Mobile calls also present the calling line identity (telepone number) of the caller, but obviously this does not assist in identifying the geographical location of the caller. In this case the mobile cell identifier is used, and again the operator's terminal offers them a choice of control room numbers relevant to the mobile cell.

If there is a problem with the main number for an emergency control room then there are a further 2 choices available for each emergency service. A second choice number in the same control room, and a third choice in a neighbouring emergency services patch. In total an operator will typically therefore have a choice of 9 possible numbers available. Cave and mountain rescue are further available options.

In the event of high volumes of emergency calls then a call centre can close other call queues to provide additional capacity to 'protect the 9's ' within the centre itself, and in the event of local network problems, or high call volumes for other reasons (tv phone votes, natural disasters) then 'call gapping' can be applied at telephone exchanges, causing a certain volume of calls to fail automatically allowing additional capacity for 999 calls to reach call centres.

In the event of a failure of the live database providing operators with the emergency centre contact numbers then a backup database is held locally at the centres which continues to automatically provide the options to the operator. In the event of a failure of the backup database then paper records were held (I assume they still are) which could be used as a last resort. In practice if the emergency database failed at one centre then emergency queues would be closed and emergency calls automatically routed to a different BT operator centre. Once at the alternative centre the calls would be handled in the same way, and would not have taken any longer to be answered.

In the event that every operator in a centre was busy on a call at the same time, then a buzzer sounds and a light illuminates to show that there is a 999 call waiting. If this is illuminated for more than a few seconds then it is practice for an operator to 'requeue' an existing call in order to take the 999 call. The requeued call would then be the next call answered, would show as having been requeued, and the BT operator would apologise to the requeued caller.

It's a comprehensive system, with recording of all 999 calls at the BT operator centre. and a printed record of all calls received and the notes added by operators. It's a responsibility that BT takes very seriously for obvious reasons.

At once hugely satisfying, immensely distressing, and frustrating, handling 999 calls is seldom dull.

With regards to '112', an interesting additional point is that BT operators experience a large volume of 'noisy 112' calls (or did, it was a while ago now). These are calls generated by line faults (wires touching trees or loose joints) which generate the electrical signals similar to someone dialling 112. As a result the operator gets a noisy emergency call. This was not something which happened before the introduction of 112, as the set of signals required to generate 999 were far less likely to have come from a wire blowing about in the wind, hence it never got routed.

[Alonso]

Yeahhh... very weird to put 999 when it is the most difficult number to dial in those phones

Here the number is 105 for police/ambulance and 116 for firefighters/ambulance

[MWISimmer]

Wasn't 112 introduced in the UK alongside 999 for emergency calls because it's a lot quicker to dial for those who still have (had ) circular dial telephones as pictured in Doug's post?