Glossary · definition
E.164 format: the international phone number standard
E.164 is the format every phone network, SMS API and sign-up form ultimately understands: a plus sign, the country code and the national number, with nothing in between. If you have ever had a verification code fail because of a space, a dash or an extra zero, E.164 is the fix. This page explains the rules, shows examples and gives a simple way to convert any number.
Quick answer
What is E.164 format?
E.164 is the ITU-T international numbering standard (current version 2010). A number in E.164 format starts with a plus sign, followed by a 1- to 3-digit country code and the national number, with no spaces, dashes or leading zero, and at most 15 digits in total. Example: +14155552671 for a US number.
What are the E.164 rules?
ITU-T Recommendation E.164, whose current edition dates from November 2010, defines the structure of international public telephone numbers. In practice, developers and apps follow a handful of rules that come from it.
- Start with + (the plus sign stands in for the international exit code).
- Then the country code: 1 to 3 digits, such as 1, 44 or 234.
- Then the national significant number, without the domestic trunk prefix (usually 0).
- Digits only: no spaces, dashes, dots or parentheses.
- No more than 15 digits in total, not counting the plus sign.
E.164 examples by country
The same number can be written many ways for people, but it has exactly one E.164 form. These examples use fictional or reserved ranges.
| Country | How people write it | E.164 format |
|---|---|---|
| United States | (212) 555-0123 | +12125550123 |
| United Kingdom | 07700 900123 | +447700900123 |
| Germany | 030 123456 | +4930123456 |
| India | 098765 43210 | +919876543210 |
| Australia | 0491 570 006 | +61491570006 |
| Brazil | (11) 91234-5678 | +5511912345678 |
| Nigeria | 0803 123 4567 | +2348031234567 |
How do I convert a phone number to E.164?
Three steps work for almost every country. Remove every space, dash, dot and parenthesis. If the national number starts with a domestic 0, drop it (Italian landlines are the main exception and keep it). Then add + and the country code in front.
Developers usually do this with a library rather than by hand, because each country has its own lengths and exceptions. Google's open-source libphonenumber is the common choice, and SMS APIs such as Twilio's expect numbers in E.164 for the To and From fields.
Why does E.164 matter for SMS verification?
Sign-up forms often split the country code and the number into two fields, then join them into E.164 before calling an SMS provider. If you type the country code twice or keep the leading 0, the joined number is wrong, and the code goes nowhere. Pasting a number with spaces into a form that does not clean it can fail the same way.
On TempSMSVerify, each number is shown with its country, so you can paste it into the country code and number fields correctly. If a code still does not arrive within up to 20 minutes, you are not charged. Country codes for common countries are listed at /glossary/country-calling-code.
FAQ
E.164 format: FAQ
What is the maximum length of an E.164 number?
Fifteen digits, counting the country code but not the plus sign. ITU-T Recommendation E.164 sets that limit for international public telephone numbers. Most real numbers are shorter: a US number in E.164 has 11 digits, a UK mobile number has 12, and many African and Asian mobile numbers have 12 or 13.
Does E.164 include the plus sign?
The plus sign is the standard way to write an E.164 number for display and in most APIs, as in +447700900123. It tells the network the number is international. Strictly, the 15-digit limit counts only digits, so the plus sign is a prefix rather than part of the number itself. Store it consistently in your systems.
Is E.164 the same as international format?
Nearly. International format for people often includes spaces, such as +44 7700 900123, which is the related ITU-T E.123 presentation style. E.164 is the machine form: the same digits with no spaces or symbols, +447700900123. Apps and SMS APIs usually need the E.164 version.
How do I write a US number in E.164?
Add +1, then the 10-digit number with the area code, and remove every space, dash and parenthesis. For example, (212) 555-0123 becomes +12125550123. US numbers have no domestic 0 to drop. The same rule applies to Canada and other countries in the North American Numbering Plan, which also use +1.
Why is my phone number invalid in a sign-up form?
Usually because the joined number is not valid E.164: the country code was typed twice, a leading 0 was kept, the number has the wrong length for that country, or the form rejected spaces and symbols. Enter the country code in its own field, then only the national digits without the 0.
Do SMS APIs require E.164?
Most do. Providers such as Twilio expect recipient and sender numbers in E.164, and many reject anything else. Using one format everywhere also prevents duplicates in databases, because the same number written three ways becomes one value. Convert input with a library like libphonenumber before storing or sending it.
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