Formatting International Phone Numbers

Twilio strongly encourages using E.164 formatting for all To and From phone numbers in API requests and TwiML scripts. This is an internationally-recognized standard phone number format that will help to ensure deliverability of calls and SMS messages across the globe. This guide will explain how E.164 formatting works.

Notice: Short Code messaging numbers do not require a plus sign or country code. For more information, see Formatting Short Code Numbers.

Recent Dialing Changes

Here are the latest phone number dialing changes. If you have Twilio phone numbers from one of these countries, and/or dial out to them, please click the below link to review the details of the change: 

E.164 Overview

E.164 phone number formatting entails the following:

  1. A + (plus) sign (replacing the International Call Prefix like 011)
  2. International Country Calling code
  3. Local Area code
  4. Local Phone number

For example, here’s a US-based number in standard local formatting: (415) 555-2671


Here’s the same phone number in E.164 formatting: +14155552671


E.164 Mobile Numbers

In a number of countries, local dialing may require the addition of a '0' in front of the subscriber number. With E.164 formatting, this '0' must usually be removed.

For example, here’s a UK-based number in standard local formatting: 020 7183 8750


Here’s the same phone number in E.164 formatting: +442071838750


Help with E.164 Formatting

If you need help determining the correct E.164 formatting for a phone number, consider using Twilio Lookup. The Lookup API can help validate any phone number to make sure it is correctly formatted to send or receive calls. Lookup also offers additional options for Caller ID and Provider lookup. Learn more about the Lookup API here.

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