A trunk prefix is a digit sequence to be dialed before a telephone number to initiate a telephone call for the purpose of selecting an appropriate telecommunications circuit by which the call is to be routed.
Methodology Telecommunication networks evolved from small, locally designed and managed networks within a city, region, state, province, etc. and grew by geographic expansion and the desire to communicate across the boundaries of such networks. For this purpose special trunks became available by which calls are routed for interconnection of different networks. The telephone numbering plans were typically incompatible with those in other networks. Telephone companies enabled the routing via external trunks to other networks by requiring operators or subscribers to dial special prefix sequences prior to dialing the destination telephone number.
Before the implementation of direct distance dialing (DDD) in the United States, operators used routing codes to select specific trunks to the next intermediate destination, or, in Operator Toll Dialing, an area code to forward the call to a remote numbering plan area toll switch. In Direct Distance Dialing the newest local (Class 5) switching systems did not require special prefixes in addition to the area code, but older systems were retrofitted with equipment that enabled a toll trunk by dialing a special prefix sequence.
Today, making a domestic (national) telephone call usually requires the dialing of a single or two-digit national trunk prefix preceding any area codes and the destination subscriber number. In most countries, the trunk prefix is 0.
For international telephone calls the caller must dial an international trunk prefix, followed by the destination's country code. Many mobile telephone systems also permit dialing the character + in place of the International trunk prefix to automatically substitute the appropriate code for the origination country.
For displaying an international telephone number in directories, business cards, or stationery, a telephone number is represented by prefixing it with a plus sign and the country code, without any local trunk prefixes.
Countries using national trunk prefixes
Countries that use 0 as national trunk prefix
Africa
Egypt Morocco Kenya South Africa Sudan Tanzania Rwanda Nigeria Libya
Angola
South America
Argentina Brazil Paraguay Peru Venezuela
Asia
Afghanistan Azerbaijan Bangladesh Cambodia China (landlines only) India (landlines only) Indonesia Iran Israel Japan Jordan Laos Malaysia Myanmar North Korea Nepal Pakistan Philippines Saudi Arabia South Korea Sri Lanka Taiwan Thailand Uzbekistan Vietnam United Arab Emirates
Europe
Albania Austria Belgium Bosnia and Herzegovina Bulgaria Croatia Finland France Georgia Germany Ireland Lithuania Moldova Montenegro Netherlands North Macedonia Romania Serbia Slovakia Slovenia Sweden Switzerland Turkey Ukraine United Kingdom
Oceania
Australia New Zealand
Countries that use 8 as national trunk prefix
Belarus Kazakhstan Russia (change to 0 planned) Turkmenistan
Countries that use other trunk prefixes The number next to a country denotes its national trunk prefix.
Mexico – 01 Mongolia – 01 or 02 Hungary – 06 North American Numbering Plan countries – 1
Countries that no longer use a national trunk prefix
Bolivia Chile Cyprus Czech Republic Denmark Estonia Greece — the prefix 0 was replaced by 2 for landlines and 6 for mobile phone numbers, which are now part of the number Italy — the leading 0 is dialed both within and from outside Italy, because 0 is now part of the number and not the trunk code Latvia Luxembourg Malta Monaco Nepal Norway Oman Poland Portugal San Marino — the leading 0 is dialed both within and from outside Italy, because 0 is now part of the number and not the trunk code Spain Uruguay Vatican City — the leading 0 is dialed both within and from outside Italy, because 0 is now part of the number and not the trunk code Singapore
See also Subscriber trunk dialling
References
External links — World Telephone Numbering Guide