International Country
Calling Codes & Area Code Directory

What Is a Country Calling Code?

A country calling code, also known as an international dialing code or IDD prefix, is a numeric prefix assigned to each country or territory by the International Telecommunication Union (ITU). These codes allow telephone networks worldwide to route calls across borders. When you place an international call, the country code tells the network which nation you are trying to reach. For example, the United States and Canada share the country code +1, the United Kingdom uses +44, and India uses +91.

Country codes range from one to three digits. Zone 1 covers North America and the Caribbean under the North American Numbering Plan (NANP). Zone 7 serves Russia and Kazakhstan. Zones 2 through 6 and 8 through 9 are distributed across Africa, Europe, South America, Asia-Pacific, and the Middle East. Beyond the country code, most nations have area codes or city codes that further route the call to a specific region or carrier. Understanding these codes is essential for anyone making international calls, sending SMS messages, or configuring VoIP and business phone systems.

Understanding ISO Country Codes

The International Organization for Standardization (ISO) maintains the ISO 3166 standard, which defines codes for countries, dependent territories, and special areas of geographical interest. ISO 3166-1 alpha-2 assigns two-letter codes (e.g., US for the United States, GB for the United Kingdom), while alpha-3 uses three-letter codes (USA, GBR). These codes are used globally in internet domain extensions (ccTLDs), currency identifiers, passport machine-readable zones, and shipping labels. They are not the same as phone calling codes, although they often appear alongside them in reference directories like this one.