Trunk Prefix

A trunk prefix is a digit sequence to be dialed before the telephone number to initiate a telephone call for the purpose of selecting an appropriate telecommunications circuit by which the call is routed.

In most countries making a domestic telephone call requires the dialing of a single digit preceding any necessary area codes and subscriber numbers. In most countries, such as Australia, Germany and the United Kingdom, the trunk prefix is 0. In the North American Numbering Plan it is 1. When the same telephone number is called from another country, the national trunk prefix is not dialed, instead for international calls an international trunk access code is typically required. Many countries use the sequence 00, but in the United States and the NANP areas it is 011.