The 999 System and It's uses

What is 999?
In the UK 999 is an all-service number, in that it should be called in any situations where state-run emergency services are needed. The three main services are the police, fire and rescue and ambulance. Other available services include coastguard, mountain rescue and cave rescue, where locally relevant. In some situations there will be specific instructions on nearby signs to notify some other authority of an emergency before calling 999. For example, there are notices on bridges carrying railways over roads informing that, if there is a road vehicle striking the bridge, the railway authority (on a given number) should be called first and only then 999 to inform the police.
In the UK, the number is operated by BT, Cable & Wireless and Global Crossing. These organizations forward calls to the appropriate emergency service for the location and incident; all calls to the number are made free of charge. The operation of 999 is coordinated by the 999 liaison committee.
999 is used to contact the emergency services upon witnessing or being involved in an emergency. In the United Kingdom, the numbers 999 and 112 both correspond to the same line, and there is no priority or charge for either of them.
An emergency can be:
• A person in immediate danger of injury or their life is at risk
• Suspicion that a crime is in progress
• Another serious incident which needs immediate emergency service attendance

What will happen when I call 999?
On dialing 999 an operator will come onto the line and ask "Emergency. Which service?”Previously operators asked "Which service do you require?" (Approximately up to the mid-90s.) If the caller is unsure as to which service they require, the operator will default the call to the Police, and if an incident requires more than one service, for instance a Road Traffic Collision with injuries and trapped persons, depending on the service the caller has chosen, the service will alert the other services for the caller (while the BT/C&W/etc Operator has to also contact each emergency service individually, regardless of whether the caller has remained on the line). The caller will be connected to the service which covers the area that they are (or appear to be) calling from.

Where did the 999 system come from?
The 999 service was introduced on 30 June 1937 in the London area, and later nationally.
The number 999 was chosen because of the need for the code to be able to be dialed from A/B button public telephones. The telephone dial (GPO Dial No 11) used with these coin-boxes allowed the digit "0" to be dialed 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.
Since the introduction of mobile phones, the choice of the number 999 has become a particular problem for UK emergency services, as same-digit sequences are most likely dialed by accident due to vibrations and other objects colliding with a keypad. This problem is less of a concern with emergency numbers that use two different digits (e.g., 112, 911).

What are Silent, Abandoned and Hoax calls?
An abandoned call is when a caller intentionally or otherwise, rings 999 and then disconnects or stays silent; this could be for any number of reasons, including coercion or harm coming to the caller. Abandoned calls are filtered by BT operators and are either disconnected or put through to the police.
The most common reasons for abandoned calls include:
• Accidental calling by dialing 999 on mobile phones, even with the keypad locked. All GSM mobile phones have a feature of still allowing emergency calls to be dialed even with a keypad lock on.
• Faulty lines.
Hoax calls are a problem for emergency services. Tied up lines and vehicles can disrupt critical service.
On 30 December 2006, West Midlands Ambulance Service gave examples of inappropriate uses of 999 during the festive period, including: a man who could not find his trousers; a man who "couldn't walk from too much dancing"; a man with a finger injury he had sustained two days earlier; and an 18-year-old man who had a toothache.2008 also saw some abused lines as one reveler called up 999 to ask where New York was, and what time it was there.