International Calling Codes: How E.164 Phone Numbers Work

The three parts of an international number

Every public phone number in the world fits one pattern, set out in ITU-T Recommendation E.164, the international numbering plan maintained by the International Telecommunication Union. First published in 1988 and last revised in June 2020, it says that a full international number has at most 15 digits, not counting the exit code you dial before it. Those digits split into up to three parts:

• Country code (CC): 1 to 3 digits, such as 1 for the United States, 44 for the United Kingdom or 977 for Nepal. Never 4.
• National destination code (NDC): optional. Often an area code or a mobile network prefix. Some countries with small "closed" numbering plans have no separate NDC at all.
• Subscriber number (SN): the line itself.

The plus sign is not a digit. It is shorthand for "insert your country's exit code here", which is why a number written as +44 20 7946 0958 works from any mobile phone in any country. Mobile networks translate the plus for you; on many landlines you still have to dial the exit code yourself.

Nine world numbering zones

Country codes are grouped by their first digit into nine "world numbering zones", a scheme that dates from the 1960s, before E.164 itself. The first digit tells you roughly where a number was issued. Zone 1 and zone 7 are unusual: each holds a single one-digit code shared by more than one country. Most other zones are full of 2- and 3-digit codes, and short codes went to the countries that were large telephone markets when the plan was drawn up (France 33, Germany 49, Japan 81).

Counts are geographic country codes in Google's libphonenumber metadata (version 9.0.42), which tracks the ITU's assignments; spare and reserved codes are not counted.

Codes that belong to no country

Not every country code points at a place. The ITU also assigns 3-digit codes to global services, and for these the rest of the number is limited to 12 digits. The main ones are +800 (international freephone), +808 (international shared-cost numbers), +870 (Inmarsat satellite phones), +881 (global mobile satellite systems such as Iridium), +882 and +883 (international networks) and +979 (international premium rate). A number starting with one of these tells you nothing about a location.

Shared codes: +1 and +7

+1, the North American Numbering Plan

The United States, Canada and much of the Caribbean share one country code. The North American Numbering Plan (NANP) began with AT&T's nationwide plan of October 1947, and every NANP number has 10 digits after the 1: a 3-digit area code, a 3-digit exchange code and 4 digits. The area code, not the country code, is what tells the members apart. Jamaica is +1 876 and the Bahamas +1 242, so a call from New York to Kingston is dialed like a US long-distance call.

On Beelad, the 13 sovereign NANP members show their area code next to the shared code, for example Jamaica's page shows +1-876, and each page lists the other countries that share +1.

+7, Russia and Kazakhstan

Code 7 belonged to the Soviet Union. After the USSR dissolved in 1991, Russia and Kazakhstan kept sharing it. The networks tell them apart by the digits right after the 7: Kazakh numbers begin +7 6 or +7 7 (a mobile number might be +7 701 …), while Russian numbers start with other digits such as 3, 4, 8 and 9 (Moscow landlines are +7 495 …).

Kazakhstan did plan to leave. The ITU reserved code +997 for it in 2021, and the switch was scheduled to start on 1 January 2023 with a period in which both codes would work. In November 2023 the plan was dropped, and as of October 2026 Kazakh numbers still use +7; +997 is not in service. Both the Kazakhstan and Russia pages on Beelad show +7.

Exit codes: what you dial first

The exit code (also called the international call prefix) belongs to the country you are calling from. The ITU recommends 00, and most of Europe, Africa, the Middle East and South Asia use it. The exceptions are the ones that catch travelers.

The trunk prefix trap

Inside most countries, national numbers start with a trunk prefix, usually 0 (1 in the NANP, 8 in Russia and Kazakhstan). It is part of domestic dialing, not of the number, so it disappears when you add the country code. A UK number written 020 7946 0958 becomes +44 20 7946 0958, never +44 020….

Italy is the well-known exception. Its landline numbers keep the leading 0 after the country code, so a Rome number 06 4567 8901 is dialed from abroad as +39 06 4567 8901. San Marino and the Vatican follow the same rule. A simple "strip the first zero" script breaks Italian numbers.

What a calling code does not tell you

A calling code shows where a number was issued, not where its owner is. A Kenyan +254 mobile keeps that code while roaming in Germany. Virtual numbers can be bought in one country and used anywhere online, and global service codes such as +882 have no country at all. Number portability blurs things further: even Google's libphonenumber says its carrier lookup gives "only the original carrier" of a number range, not the current one.

For developers, that means a phone prefix is fine for pre-filling a country picker or choosing a display format, but it is a poor basis for tax, fraud or legal decisions about where a person is.

Storing numbers in software

• Store numbers in E.164 form: a plus sign followed by digits only, such as +442079460958.
• Parse user input with a maintained library such as libphonenumber (Java, C++, JavaScript, with ports such as Python's phonenumbers). It knows each country's trunk prefix, the Italian leading zero and valid number lengths.
• Ask for the country separately when users type national numbers. 020 7946 0958 means nothing without knowing it is British.
• Format for display at the last moment, in national or international style depending on the reader.

Calling codes are one of several code systems on each country page. The ISO country codes guide covers the two- and three-letter codes, and the ccTLD guide covers internet domains like .kz. If you are calling across borders, also check the local time with the time zone guide.

Quick checklist

• Country codes have 1 to 3 digits; a full international number has at most 15.
• Write numbers as +CC plus the national number without its trunk prefix, except in Italy, San Marino and the Vatican, where the 0 stays.
• Your exit code depends on where you are: 00 in most countries, 011 in North America, 010 in Japan, 0011 in Australia.
• +1 covers 25 countries and territories, and +7 covers Russia and Kazakhstan; Kazakhstan's planned +997 was dropped in 2023.
• A calling code tells you where a number was issued, not where the caller is.