Emergency telephone number
Most public switched telephone networks have a single emergency telephone number (sometimes known as the universal emergency telephone number or the emergency services number) that allows a caller to contact local emergency services for assistance. The emergency number differs 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.
In many countries, dialing either 1-1-2 (used in Europe and parts of Asia) or 9-1-1 (used in the Americas) will connect callers to emergency services. For individual countries, see the list of emergency telephone numbers.