What is the E.164 Format and How to Use It?

The E.164 phone number is a telephone number format introduced by the International Telecommunication Union to ensure each PSTN (Public Switched Telephone Network) device worldwide has a unique number. This standardized structure provides a consistent structure, simplifying the process of making international calls and sending text messages overseas.

In simple terms, the E.164 format serves as a standard for dialing a phone number internationally, ensuring that your call or message is routed correctly regardless of the person's location.

E.164 phone number is formatted as a “+” symbol followed by a country code and a recipient’s phone number (area code + subscriber’s number).

E.164 number format: [+] [country code] [area code] [Subscriber Number]

• The “+” Symbol: Signals you are making an international call.
• Country Code: Indicates the country of origin for the number.
• Area Code/NDC: Indicates the specific region or telephone network within a country.
• Subscriber Number: The unique number of the person you’re trying to reach.

To dial an E.164 phone number, enter “+”, the country code, and the area code, followed by the subscriber’s number.

Step 1: Dial the “+” sign 
Step 2: Enter the country code of your dialing nation.
Step 3: Dial the area code of your target region.
Step 4: Enter the subscriber’s unique number.

For instance, to call Mexico from the US, dial +52 81 1234 56X

• 52 - Mexico country code
• 81 - Monterrey area code
• 1234 56X - Subscriber’s number

E.164 Format for US Phone Number: +1718555123X

• 1 - US country code
• 718 - New York City area code
• 555 123X - Subscriber’s number

E.164 Format for UK Phone Number: +44207946095X

• 44 - United Kingdom country code
• 20 - London area code
• 7946 095X - Subscriber’s number

E.164 Format for Australia Phone Number: +6129876543X

• 61 - Australia country code
• 2 - New South Wales area code
• 9876 543X - Subscriber number

E.164 Format for Italy Phone Number: +39061234567X

• 39 - Italy country code
• 06 - Rome area code
• 1234 567X - Subscriber’s number

When formatting an E.164 number, ensure the “+” sign is included, avoid extra zeros from the trunk codes, use correct country or area codes, adhere to the digit limit, and ensure the phone number is dialed correctly.

1. Misunderstanding the Length: The length of E.164 numbers should never exceed the maximum of 15 digits, including the country code.
2. Not Including the Plus Sign: The "+" sign is essential for indicating international dialing.
3. Using the Wrong Country Code: Make sure you use the correct country code for the recipient’s location.
4. Adding the Trunk Code: Omit the trunk code when calling from abroad (except some specific countries).
5. Entering the Wrong Area Code or Recipient's Number: Double-check the area code and the telephone number to avoid dialing the wrong number.

The E.164 format is a global standard for dialing international phone numbers. It ensures that every phone number is unique, easily recognizable, and can be reached accurately. While the structure remains the same, the unique combination of country codes and area codes differentiates phone numbers across various countries.

E.164 standards are guidelines for writing international phone numbers worldwide. It starts with a '+' sign, followed by a country code, area code, and unique contact number, with a maximum of 15 digits. The number is written without spaces or special characters.

To convert to E.164, remove any local formatting (like clauses or dashes), add the country code, and ensure the number is written without spaces. For example, ABC-555-2678 becomes +1ABC5552678, where 1 is the country code of the US, and ABC is the area code.

The E.164 ensures proper call and message routing by assigning a unique number for each device worldwide.

Yes, E.164 is compatible with both landline and mobile phone numbers. In the E.164 format, mobile numbers are represented as: + (plus sign), followed by the country code and mobile number.

Yes, all countries use the same E.164 format. However, while the structure remains consistent, the number length, country codes, and area codes vary by country.