What is the E.164 number format?

The E.164 number format is an internationally recognized standard for phone numbers, established by the International Telecommunication Union (ITU). It is used to ensure consistency and reliability in global telecommunications by setting rules for how phone numbers are formatted, transmitted, and dialed across different countries and networks. This format is essential for maintaining a unified structure, allowing people worldwide to connect with each other without confusion.

A phone number in the E.164 format includes the numbers country code just like a standard international format. The main difference is that the rest of the number does not contain any spaces, dashes or other additional characters. Numbers in the E.164 format also cannot be any longer than 15 characters. This is what makes the E.164 a clean, readable format for storing international numbers.

The E.164 format was established by the International Telecommunication Union (ITU) in 1984 to standardize phone numbers globally, ensuring consistency in how numbers are structured, transmitted, and dialed across countries. It evolved from earlier standards, notably E.163, which was limited to landline telephony. As telecommunications expanded rapidly, E.164 introduced a structured format: a country code followed by up to 15 digits and a leading ‘+’ sign, enabling seamless international communication across traditional phone networks. This format allowed for efficient routing and compatibility across both fixed-line and mobile networks, supporting a growing number of international and cross-network calls.

With the rise of digital and mobile technologies, E.164 became essential for mobile phones, VoIP, and internet-based communication services like WhatsApp and Skype, offering a consistent numbering standard across platforms. Today, E.164 continues to serve as a fundamental standard for global telecommunications, ensuring reliable connections across diverse systems. It is also critical for modern applications, from e-commerce to cloud-based telephony and IoT. As new technologies like 5G and IoT emerge, E.164 remains a backbone for global connectivity, evolving to support future communication needs.

Why is the E.164 format useful?

The E.164 format is useful because it provides a consistent, globally recognized structure for phone numbers, enabling seamless communication across countries and networks. By standardizing numbers with a country code, a maximum of 15 digits, and a leading ‘+’ sign, E.164 makes it easy to identify and dial international numbers without confusion.

This format is particularly beneficial for digital services like VoIP, mobile apps, and messaging platforms, as it ensures compatibility across devices and networks, allowing users to connect easily worldwide. For businesses, E.164 simplifies customer data management by providing a uniform way to store and validate numbers, reducing errors in contact information and enabling reliable communication. Its widespread adoption across modern technologies ensures it will continue to support and simplify global connectivity as new communication platforms emerge.

What are some examples?

Two examples help illustrate the E.164 format in action. The first example is a phone number in the United States: a local number might be displayed as (555) 123-4567. In E.164 format, this becomes +15551234567, where ‘+1’ is the U.S. country code, followed by the 10-digit national number. This standardized format ensures the number is recognizable globally, allowing it to be dialed easily from any country.

A second example is a number in the United Kingdom: a local number such as 020 7946 0958 would convert to +442079460958 in E.164 format. Here, ‘+44’ represents the UK country code, followed by the national number without spaces or other characters. These examples highlight E.164’s clear structure, which removes regional formatting variations and enables a seamless international dialing experience.