Glossary

E.164

E.164 is the ITU-T international public telecommunication numbering plan, which defines phone numbers as a country code followed by a national significant number, up to 15 digits in total, conventionally written with a leading plus sign and no spaces or trunk prefix (for example +14155550123).

Updated 26 Sept 2026By PhoneBorn TeamEditorial policy

Format rules

Start with +, which stands for the international access code of whatever country you are dialling from (00, 011 and so on).
Then the country code (1–3 digits).
Then the national significant number — the number without the domestic trunk prefix such as a leading 0.
Maximum 15 digits in total, excluding the plus sign.
For storage and APIs: digits only after the plus sign — no spaces, dashes, dots or brackets.

Examples

Country	How it is written locally	E.164
United States	(415) 555-0123	+14155550123
United Kingdom	07700 900123	+447700900123
Germany	0151 23456789	+4915123456789
India	098765 43210	+919876543210

The most frequent error is keeping the trunk 0: +44 07700 900123 is invalid. Italy is a notable exception: its fixed-line numbers keep their leading 0 after the country code (+39 06…), because the 0 is part of the national number there.

Why it matters for verification

Verification systems normalize every number to E.164 before sending a code, looking it up or checking duplicates. A number entered with the wrong country code or an extra trunk 0 may be rejected as invalid, or the code may be sent to a different number altogether. When a sign-up form has a separate country selector, pick the country and type the national number without the leading 0.

For developers, storing numbers in E.164 makes them unambiguous across countries; libraries such as Google's libphonenumber handle parsing and validation. PhoneBorn shows numbers in international format in the dashboard and through the phone number API, so they can be pasted directly into sign-up forms. Formatting details for each country appear on the countries pages.

Put it into practice

E.164: FAQ

Do I include the 0 when writing a number in E.164?

In most countries, no. Drop the domestic trunk prefix (usually 0) and put the country code in front, for example +44 7700 900123 instead of 07700 900123. Italy's fixed-line numbers are a well-known exception.

How long can an E.164 number be?

At most 15 digits, counting the country code but not the plus sign. Many numbers are shorter; for example, US numbers have 11 digits including the country code 1.