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What is the E.164 phone number format?

Updated

Short answer

E.164 is the ITU-T international numbering plan. An E.164 number is written with a leading plus sign, the country code and the national number, with at most 15 digits and no spaces or punctuation, for example +971501234567. To convert a local number, drop the national trunk prefix (usually 0) where the country uses one, add the plus and the country code, and remove spaces and brackets.

Examples by country

The numbers below are illustrative placeholders. Trunk prefixes come from ITU's dialling-procedures table, a December 2011 position, so confirm a specific country with a library such as libphonenumber.

CountryLocal form (example)E.164
UAE050 123 4567+971501234567
United Kingdom07700 900123+447700900123
Italy (landline)06 1234 5678+390612345678
United States(202) 555-0123+12025550123

Why it matters for WhatsApp and SMS

Meta strongly recommends including the plus sign and country calling code in WhatsApp send requests. Without the plus sign, the sender's country calling code is added to the number, which can send the message to a wrong number. Store clean E.164 and send exactly that.

Common mistakes

  • Always dropping the leading zero: ITU's table lists no trunk prefix for Italy, Spain and Qatar.
  • Using a regex as validation: it checks shape only, while libphonenumber checks validity for a country.
  • Letting Excel treat phone columns as numbers, which drops leading zeros and shows long numbers in scientific notation. Format the column as Text.
  • Assuming a valid format means a reachable number.

Official sources