Today it means: The telephone number for emergency services on all GSM cell phones and in the EU, Russia, United Kingdom, India, Indonesia, Turkey, Ukraine, Cameroon, Ghana, Guinea-Bissau, Kenya, Mali, Nigeria, Rwanda, Sao Tome, the Seychelles, Uganda, East Timor, Iraq, Kazakhstan, Kuwait, Tajikistan, Turkmenistan, Armenia, Azerbaijan, Moldova, North Macedonia, Vatican City, New Caledonia, Vanuatu, and Saint Vincent. Full definition →
Selected by the European Union as the 3-digit number fastest to dial on cellular and rotary phones without the likelihood of accidental dialing caused by hanging up a landline telephone, sometimes interpreted by phone networks as a 1.
Etymology from Wiktionary, CC BY-SA 4.0.