999 (emergency telephone number)
999 is the United Kingdom's and Ireland's emergency telephone number and Poland's medical emergency number. They are all used alongside the EU standard 112. Either number can be used but 999 is more popular and better-known than 112. It is also the emergency telephone number in some Commonwealth countries including  Bangladesh, Botswana, Ghana, Malaysia and Singapore (the rest use a variety of numbers, including 9-1-1). It is also used in the United Arab Emirates, Hong Kong, Macau, Bahrain and Qatar.
It is an all-service number, meaning that it should be called in any situations where state-run emergency services are needed. The three main and best-known services are police, fire & rescue services and ambulance/paramedics. Other available services  include coastguards, mountain rescue and cave rescue (where locally relevant). Some situations such as a major car accident or a terrorist attack (including nuclear, biological, or chemical attacks) will require multiple and/or specialist services but the first point of call for reporting such incidents from the general public is still the 999 system. 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 telling people that, if they see a road vehicle striking the bridge, they should call the railway authority (on a given number) first and then call 999 to inform the police.
In the UK, the number is operated by BT, Cable & Wireless, Kingston Communications and Global Crossing.  These organisations 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.

# United Kingdom
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 coin-boxes 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 coin-box 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.
It was decided that the number for emergency services should be 999 as 222, 333, 444, 555, 666, 777, 888, 000 were already in use and 111 could be dialled by the wind blowing the phone lines.
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 dialled 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).
The pan-European 112 code was introduced in the UK by BT in December 1992, with little publicity. It connects to existing 999 circuits. In common with 999, many manufacturers of GSM phones allow the dialing of 112 even without unlocking the keypad, a feature that can save time in emergencies but that also causes some accidental calls.
Both 999 and 112 calls can be made from any mobile phone regardless of whether that phone has a SIM card in it or not, as long as there is a signal available. Even then, emergency coverage is often available in places where ordinary calls cannot be made, such as in parts of the London Underground.
On 6 October 1998, BT introduced a new system whereby all the information about the location of the calling telephone was transmitted electronically to the relevant service rather than having to read it out (with the possibility of errors). This system is called EISEC (Enhanced Information Service for Emergency Calls)
Access to the emergency service is provided for the hearing impaired via Textphone and use of the national 'typetalk' relay service. The number is 18000, having previously been 0800 112999.
Since May 2006 a new non-emergency telephone number 101 has been available, initially in Hampshire, and then in Northumbria, Cardiff, South Yorkshire, and 'Leicester and Rutland' for calls to the police that did not require an immediate police response.  It will be rolled out across England and Wales by 2008  and will cost 10p per call. It is believed that the many non-emergency calls made through the 999 number can be more efficiently dealt with through a second number. Some who have access don't use it because they aren't aware of it, or simply because 999 is free of charge and 101 is not.
On 30 December, 2006, West Midlands Ambulance Service gave Christmas 2006 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; an 18-year-old man who had a toothache.

# Hong Kong
999 was introduced to Hong Kong during British rule and continues to be used following the handover in 1997.

# 999 services
- Fire Service
- Ambulance
- Police
- Coastguard
(Mud Rescue and Cliff Rescue come under the Coastguard)
- Mountain Rescue
- Cave Rescue
- Bomb disposal
- Nuclear Emergency