Emergency telephone number

related topics
{system, computer, user}
{service, military, aircraft}
{law, state, case}
{math, number, function}
{area, community, home}
{city, large, area}
{area, part, region}
{country, population, people}
{town, population, incorporate}

Many countries' public telephone networks have a single emergency telephone number, sometimes known as the universal emergency telephone number or occasionally the emergency services number, that allows a caller to contact local emergency services for assistance. The emergency telephone number may differ from country to country. It is typically a three-digit number so that it can be easily remembered and dialed quickly. Some countries have a different emergency number for each of the different emergency services; these often differ only by the last digit. Inside the European Union 112 has been introduced as a common emergency call number during the 1990s, and is a well known emergency number in the world today alongside with 911 and 999.

Contents

Emergency numbers and mobile telephones

Mobile phones can be used in countries with different emergency numbers. A traveller visiting a foreign country does not have to know the local emergency numbers, however. The mobile phone and the SIM card have a preprogrammed list of emergency numbers. When the user tries to set up a call using an emergency number known by a GSM or 3G phone, the special emergency call setup takes place. The actual number is not even transmitted into the network, but the network redirects the emergency call to the local emergency desk. Most GSM mobile phones can dial emergency calls even when the phone keyboard is locked, the phone is without a SIM card, or an emergency number is entered instead of the PIN.

Most GSM mobile phones have 112, 999 and 911 as pre-programmed emergency numbers that are always available.[1] The SIM card issued by the operator can contain additional country-specific emergency numbers that can be used even when roaming abroad. The GSM network can also update the list of well-known emergency numbers when the phone registers to it.

Using an emergency number recognized by a GSM phone like 112 instead of another emergency number may be advantageous, since GSM phones and networks give special priority to emergency calls. A phone dialing an emergency service number not recognized by it may refuse to roam onto another network, leading to trouble if there is no access to the home network. Dialing a known emergency number like 112 forces the phone to try the call with any available network.

Full article ▸

related documents
Personal digital assistant
Symmetric multiprocessing
Ethernet over twisted pair
Amiga 600
Digital Video Broadcasting
Terminate and Stay Resident
Desktop environment
Revision control
Time division multiple access
PKZIP
Slow-scan television
Digital Audio Tape
Video Graphics Array
Virtual LAN
Hercules Graphics Card
Load balancing (computing)
File server
Data Link Layer
Gigabit Ethernet
IBM System/370
Winamp
LAN switching
Video CD
Multicast
Multiprotocol Label Switching
Keystroke logging
Data transmission
Computer display standard
Signaling System 7
IBook