Trunk prefix

A trunk prefix is a digit sequence to be dialled 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.

Making a domestic (national) telephone call usually requires the dialling 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 national trunk prefix is not dialled; instead, an international trunk prefix (or "+") is typically required, followed by the destination's country code.