An international dialing code (also called a country calling code or international prefix) is a numeric code you dial before a phone number when calling from one country to another. For example, +1 for the United States, +44 for the United Kingdom, and +86 for China. These codes are assigned by the International Telecommunication Union (ITU).

To make an international call, dial your country's exit code (e.g., 011 from the US, 00 from most European countries), followed by the destination country's dialing code, then the local phone number. On mobile phones, you can use the "+" symbol followed by the country code instead of the exit code — for example, +44 20 1234 5678 for a London number.

The NANP is a telephone numbering system that covers 25 countries and territories, including the United States, Canada, Bermuda, and many Caribbean nations. All NANP members share the country code +1. When calling between NANP countries, you dial 1 + area code + local number, similar to domestic long-distance calls within the US.

Among commonly referenced codes, Zimbabwe has +263, Zambia +260, and Uganda +256 — these are among the higher numeric values. The ITU assigns codes based on geographic zones: Zone 1 (North America) uses +1, Zone 2 (Africa) uses +2xx, Zone 3-4 (Europe) uses +3x and +4x, Zone 5 (Americas) uses +5x, Zone 6 (Asia-Pacific) uses +6x, Zone 7 (Russia/CIS) uses +7, Zone 8 (East Asia) uses +8x, and Zone 9 (Central/South Asia) uses +9x.

Several countries share codes due to historical, political, or regional arrangements. The most notable example is +1, shared by all NANP countries. Russia and Kazakhstan both use +7 (a legacy of the Soviet era). Sharing a code requires coordination to ensure phone numbers don't conflict across borders.

The "+" sign is a universal placeholder that represents whatever exit code your country uses. For example, from the UK (exit code 00), +1 becomes 001. From the US (exit code 011), +44 becomes 01144. Using "+" before a country code ensures the correct prefix is dialed regardless of where you're calling from. Mobile phones automatically convert "+" to the correct exit code.

There are approximately 240 assigned country calling codes, covering all sovereign states, dependent territories, and special services. Some codes are reserved for specific purposes, like +800 for international toll-free numbers and +882 for international networks. The ITU regularly updates the list in its recommendation E.164.

Group codes by geographic zone (e.g., Europe mostly +3x/+4x, Asia +8x/+9x). Notice patterns: neighboring countries often have similar codes (Germany +49, Austria +43, Switzerland +41). Create mnemonics: +39 for Italy (think "3=tree, 9=fine" — Italian cypress trees). Practice regularly with quizzes like this one — spaced repetition helps commit codes to long-term memory.