International dialing prefixes are used when dialing international telephone calls by telephone users. These prefixes are typically required only when dialling from a landline, while in GSM-compliant mobile phone (cell phone) systems, the symbol + before the destination country code may be used irrespective of the location of the telephone when dialing. The network operator provides the access codes automatically.

The following is a non-exhaustive list of countries that optionally allow for carrier selection in addition to using the standard prefix listed in the preceding section.

The following are international call prefixes that were used in various countries sometime in the past but are no longer used.