Introduction

The E.164 phone number format is an international standard for phone number representation. The International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) defines this format. E.164 numbers can have a maximum of 15 digits and include a country code, but do not include international call prefixes.

Key Components of E.164 Format

E.164 formatted phone numbers contain:

• The prefix ”+”.
• Country Code: This is a one- to three-digit code that identifies the country. For example, "1" is the country code for the United States and Canada, and "91" is the country code for India. For the full list of country codes, refer to Country Codes.
• National Destination Code (NDC): This code identifies a specific region or network within the country.
• Subscriber Number (SN): This is the unique number assigned to the subscriber.

Following is an example of a phone number in E.164 format:

An E.164 formatted phone number for a US number might look like this: +12125551234

• "+" indicates the prefix of the E.164 format.
• "1" is the country code for the US.
• "212" is the NDC (area code in this case).
• "5551234" is the subscriber number.

Convert Local Formats to E.164

If you know the country code, you can easily convert a locally formatted phone number to an E.164 formatted number. Perform the following steps:

1. Remove any spaces, parenthesis or other punctuation.
2. If the number begins with a zero, remove the leading zero.
3. Prepend the country code.
4. Prepend a ”+”.