List of international call prefixes

Not to be confused with 'country calling codes'.

An international call prefix or dial out code is a trunk prefix used to select an international telephone circuit for placing an international call. The prefix must be dialed before the country calling code and the destination telephone number. It is synonymous with international access code or exit code. The international call prefix is part of the telephone numbering plan of a country for calls to another country.

The International Telecommunication Union (ITU) recommends the sequence 00 as a standard for an international call prefix, and this has been implemented by many countries, but not all of them. Some countries use the 00 prefix which is followed by the international carrier code.

When phone numbers are published for use abroad they typically include the country calling code, but show a plus sign (+) prefix in place of any international call prefix, to signify that the caller should use the prefix code appropriate for their country.

International call

International telephone calls are those made between different countries. These telephone calls are processed by international gateway exchanges (switches). Charges for these calls were high initially but declined greatly during the 20th century due to advances in technology and liberalization. Originally they were placed via long-distance operators. The calls were transmitted by cable, communications satellite, radio, and more recently, fiber optics and Voice over Internet Protocol (VoIP). International Direct Dialling was introduced in the 1970s, so calls can be dialed by country code without an operator.

International calls can be paid via telephone card (aka phone card, calling card). These popular telecommunications products allow users to initiate an international call from almost anywhere in the world. These cards typically offer rates lower than most traditional long distance products and services, and can be used via landline, cellular phone, PBX, and some VoIP services, as well as from some airports and hotels.

United States

Coordinates: 40°N 100°W / 40°N 100°W / 40; -100

The United States of America (USA), commonly referred to as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major territories and various possessions. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is in the northwestern part of North America and the state of Hawaii is an archipelago in the mid-Pacific. The territories are scattered about the Pacific Ocean and the Caribbean Sea. At 3.8 million square miles (9.842 million km²) and with over 320 million people, the country is the world's third or fourth-largest by total area and the third most populous. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The geography and climate of the United States are also extremely diverse, and the country is home to a wide variety of wildlife.

Hong Kong

Hong Kong (香港; "Fragrant Harbour"), officially Hong Kong Special Administrative Region of the People's Republic of China, is an autonomous territory on the southern coast of China at the Pearl River Estuary and the South China Sea. Hong Kong is known for its skyline and deep natural harbour. It has a land area of 1104 km² and shares its northern border with Guangdong Province of Mainland China. With around 7.2 million inhabitants of various nationalities, Hong Kong is one of the world's most densely populated metropolises.

After the First Opium War (1839–42), Hong Kong became a British colony with the perpetual cession of Hong Kong Island, followed by Kowloon Peninsula in 1860 and a 99-year lease of the New Territories from 1898. Hong Kong remained under British control for about a century until the Second World War, when Japan occupied the colony from December 1941 to August 1945. After the Surrender of Japan, the British resumed control. In the 1980s, negotiations between the United Kingdom and the China resulted in the 1984 Sino-British Joint Declaration, which provided for the transfer of sovereignty of Hong Kong on 30 June 1997. The territory became a special administrative region of China with a high degree of autonomy on 1 July 1997 under the principle of one country, two systems. Disputes over the perceived misapplication of this principle have contributed to popular protests, including the 2014 Umbrella Revolution.

Telephone call

A telephone call is a connection over a telephone network between the calling party and the called party.

First telephone call

The first telephone call was made on March 10, 1876 by Alexander Graham Bell. Bell demonstrated his ability to "talk with electricity" by transmitting a call to his assistant, Thomas Watson. The first words transmitted were "Mr Watson, come here. I want to see you."

This event has been called Bell's "greatest success", as it demonstrated the first successful use of the telephone. Although it was his greatest success, he refused to have one in his own home because it was something he invented by mistake and saw it as a distraction from his main studies.

Information transmission

A telephone call may carry ordinary voice transmission using a telephone, data transmission when the calling party and called party are using modems, or facsimile transmission when they are using fax machines. The call may use land line, mobile phone, satellite phone or any combination thereof. When a telephone call has more than one called party it is referred to as a conference call. When two or more users of the network are sharing the same physical line, it is called a party line or Rural phone line.