Formatting International Phone Numbers - United World Telecom Knowledgebase
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Formatting International Phone Numbers

Calling or sending messages to an international phone number may require different formatting than calling or sending messages to standard local numbers. This guide explains the proper way to format international phone numbers in order to ensure the deliverability of your international phone calls.

E.164 Formatting

We recommend that you use E.164 formatting when dialing an international telephone number. The E.164 format entails the following:

    1. A + (plus) sign or the International Call Prefix.
    2. International Country Calling Code.
    3. Local Area Code.
    4. Local Phone Number.

Local Versus International Number Format

For example, here is a US number written in standard local formatting: (561) 276-7156. Here is the same phone number written in the E.164 format: +15612767156

Mobile Number Format

In a number of countries outside the United States, the addition of a ‘0’ in front of the subscriber number is required when dialing a mobile phone number locally. With E.164 formatting, the ‘0’ must be removed.

As an example, here is a UK mobile number in standard local formatting: 074 4295 4275. Here is the same phone number in E.164 formatting: +447442954275

How to Display Your International Phone Number

The phone numbers that we provide generally follow the same rules as any other local telephone number. Domestic calls should be dialed just like any standard number.

E.123 Notation

We recommend that you display your new phone numbers according to E.123 (https://www.itu.int/rec/T-REC-E.123) formatting. E.123 provides guidelines for the presentation of national and international telephone numbers, email addresses, and web addresses.

Additional Factors to Consider

International phone numbers may require additional formatting, but these can be dialed just like any standard number from the destination country.

  • Domestic example: callers to a US-based phone number from a US-based landline or mobile phone use the standard 10 digit dialing plan (a 3 digit area code followed by the 7 digit subscriber number).
  • International example: callers to a US-based phone number from the UK are required to enter the UK’s dial-out code followed by the US country code (1) and then the phone number.