Have you ever tried calling someone overseas, only to be met with a “number not in service” message, even though you’re sure it’s correct? Or maybe your business sent out a text campaign globally, and half the messages didn’t get delivered. The problem often isn’t with the message or the network. It’s with the phone number format.

Phone numbers may seem straightforward until you go global. Different countries use different lengths, prefixes, and formats. A number that works in one country can be unreadable in another system. And when systems can’t agree on what a phone number should look like, communication breaks down.

This is exactly the problem E.164 was designed to solve.

In this article, we’ll break down what E.164 is, how it works, and why it plays a critical role in standardizing international phone number formatting.

What is E.164 format phone number?

E.164 format phone number is an internationally recognized standard for representing telephone numbers.

Think of it as a universal way to write down a phone number so that any phone system in the world can understand and route calls or messages to it correctly.

Here’s a breakdown of what an E.164 formatted number looks like:

• Plus Sign (+): It always starts with a plus sign which indicates that the number is in international format.
• Country Code(CC): Following the ‘+’, you’ll find the international country calling code. For example, ‘1’ for the United States and Canada, ’91’ for India, or ’44’ for the United Kingdom. This code identifies the country where the phone number is registered.
• Subscriber Number(SN): This is the actual phone number within that country, which includes the area code (if applicable) and the local subscriber number.

There are no spaces, dashes, parentheses, or any other extra characters in the subscriber number part.

Here is the comparison of local phone number formats with their E.164 equivalents for various countries:

Local vs. E.164 Phone Number Format by Country

Who developed and maintains E.164:

E.164 was developed and is maintained by the International Telecommunication Union (ITU), specifically under its Telecommunication Standardization Sector (ITU-T). The ITU is a specialized agency of the United Nations responsible for global telecommunications standards.

The ITU-T Study Group 2 (SG2) is responsible for numbering, naming, and addressing standards, including E.164. This group ensures that E.164 remains up to date with technological advancements and the evolving needs of global telecommunications.

Why Is E.164 Format Important?

The E.164 format is important because it is an internationally recognized standard for telephone numbers that ensures global uniqueness and facilitates seamless communication across borders.

Here’s a breakdown of its key benefits:

1. Global Reach and Interoperability

E.164 provides a standardized format that is recognized by telecommunication networks worldwide. That ensures that phone numbers can be used internationally without modification, allowing for accurate routing of calls and SMS messages to individual devices across different countries. By adhering to this standard, different telecommunication systems and devices can easily understand and process phone numbers, promoting interoperability.

2. Consistency and Reliability

The E.164 format provides a consistent structure for storing and processing phone numbers. This reduces errors in call and SMS routing, leading to improved deliverability and a better user experience. The format includes a mandatory country code, eliminating ambiguity and ensuring that the destination of a call or message is correctly identified, regardless of the caller’s or sender’s location.

3. Simplified International Dialing

E.164 formatted numbers simplify international dialing. Users don’t need to remember different country-specific dialing prefixes. The ‘+’ sign at the beginning of the number indicates that the subsequent digits include the country code, which is essential for international calls.

4. Prevents Fraud and Ensures Deliverability

Validating phone numbers against the E.164 format is crucial for preventing fraud, especially when capturing user information. It helps ensure that the phone number provided is a valid international number.

Using E.164 format increases the reliability of message and call delivery by providing all the necessary information (country code, area code, and subscriber number) for correct routing.

How E.164 Format Impacts Different Industries

The E.164 format plays a crucial role in multiple industries by ensuring that phone numbers are standardized, unique, and globally recognizable. Different sectors rely on E.164 for seamless communication, proper call routing, and integration with modern digital technologies. Here’s how E.164 impacts various industries:

1. Telecommunications Providers

Telecom companies, including mobile carriers and landline service providers, rely on E.164 to manage national and international call routing efficiently. Without a standardized format, calls could be misrouted, leading to failed connections and billing errors. E.164 ensures that every number is unique, allowing seamless communication between different carriers and networks.

• Regulatory Compliance (TCPA): Providers must comply with laws like the Telephone Consumer Protection Act (TCPA), which regulates automated calls and messages. E.164 helps in screening and formatting numbers correctly to avoid legal violations.
• Prevents Call Failures & Billing Errors: Standardized numbering prevents duplicate allocations, ensuring accurate billing and call routing and messaging.

2. Business & Enterprise Communications

For businesses operating globally, having an E.164-compliant number ensures customers can reach them without confusion, whether through customer support lines, sales teams, or virtual phone systems. Many companies now rely on cloud-based communication tools, where standardized numbering is essential for smooth integration.

• Supports Cloud & VoIP Systems: Business communication platforms (e.g., Zoom Phone, RingCentral, Microsoft Teams) depend on E.164 for proper number validation and call routing.
• Increase CRM & Marketing Efforts: CRM systems and sales teams use E.164-formatted numbers to prevent dialing errors, improving outreach accuracy and customer engagement.

3. Messaging & SMS Platforms

SMS marketing, customer notifications, and security-based messaging (e.g., two-factor authentication) depend on E.164 to ensure messages reach the correct recipient without delays or failures. Messaging services like Textdrip, Twilio, Nexmo, and rely on this standard to maintain high deliverability rates.

• 10DLC Compliance & Message Routing: Businesses using SMS marketing in the U.S. must comply with 10DLC (10-Digit Long Code) regulations, which require number registration. E.164 ensures that registered numbers follow the proper structure for compliance.
• Fraud & Spam Prevention: Standardized phone numbers help messaging platforms filter out invalid or suspicious numbers, reducing spam and unauthorized messaging.

4. Regulatory & Government Bodies

Governments and telecom regulators use E.164 to allocate and monitor phone numbers, ensuring a well-structured numbering system that prevents conflicts. This standard is also crucial for law enforcement, emergency services, and consumer protection agencies.

• Do Not Call (DNC) & Known Litigator Compliance: Businesses conducting outbound calls must check numbers against DNC lists and Known Litigator databases to avoid regulatory fines. E.164 formatting helps automate this process, reducing legal risks.
• Emergency Services & Public Safety: Proper number formatting ensures that emergency calls (e.g., 911, 112) are recognized and routed to the correct local dispatch center, improving response times and public safety.

Common Misunderstandings About E.164

Despite how important E.164 is in global communication, it’s often misunderstood or overlooked, especially by those outside the telecom industry. Let’s clear up two of the most common misconceptions:

1. Confusing E.164 with Phone Number Formatting Styles

Many people think E.164 is just another way to visually style a phone number—like using parentheses or dashes. For example:

• (415) 555-2671
• 415-555-2671
• +1 415 555 2671

These formats may look familiar (and even user-friendly), but they’re not E.164 compliant.

The E.164 format is all about functionality, not appearance. It requires:

• No spaces
• No brackets
• No dashes
• Just the plus sign, country code, and number (e.g., +14155552671)

This is the version telecom networks and systems actually understand when connecting calls or sending messages internationally.

2. Thinking E.164 Is Only for Telecom Providers

Another common myth is that only carriers or phone companies need to worry about E.164.

Not true.

If you run an app that sends SMS, a CRM platform with customer contact data, or any kind of messaging or calling feature – you need to care about E.164. Without it, you risk failed messages, missed calls, or bad data integration, especially when working across borders.

E.164 is just as important for software developers, marketers, and business platforms as it is for phone companies. It’s the silent hero behind seamless global communication.

How a Phone Number Validation Tool Helps You Stay E.164 Compliant

When collecting phone numbers from users across different countries—whether through your website, forms, or OTP flows—one of the biggest challenges is inconsistent formatting.

People enter phone numbers in all kinds of ways. Some use dashes, others add parentheses, and many skip the country code altogether. This quickly leads to a messy database and, worse, failed messages or verification issues.

That’s where a phone number validation tool comes in. It works quietly behind the scenes to clean up user input, standardize every entry, and make sure the phone numbers in your system are accurate, usable, and fully E.164 compliant.

Here’s how it helps:

1. It Cleans and Formats Numbers Automatically

Instead of relying on users to get the format right, the tool does the heavy lifting. It:

• Detects the right country code (even if it’s missing)
• Strips out brackets, spaces, and other clutter
• Rebuilds the number in the clean, international E.164 format

Example:
A messy input like (415) 555-2671 becomes +14155552671, which is neat, consistent, and ready to use anywhere in the world.

2. It Catches Invalid or Fake Numbers

It’s not just about how the number looks- validation tools go deeper. They check:

• Is the number real and reachable?
• Does it belong to a valid telecom provider?
• Is it the right length for the country?

This helps you filter out typos, fake numbers, or outdated entries before they cause problems.

3. It Handles Global Numbers with Ease

Different countries, different formats. Some people use a “+”, others start with “00”, and some just enter a local number. A good validation tool understands the patterns and converts all inputs into a single, reliable format like +447911123456—no matter how the user typed it.

4. It Keeps Your Data Consistent Everywhere

Whether you’re sending texts, calling customers, or verifying accounts, having phone numbers in E.164 format makes your systems run smoother. Clean, validated numbers are easier to plug into:

• SMS and calling platforms
• CRM software
• Signup and login flows
• Global messaging tools

No more delivery failures. No more duplicates. Just solid, reliable data.

5. Distinguishes Between Mobile, Landline, and VoIP Numbers

Not all phone numbers are created equal. Validation tools can tell you whether a number is a mobile phone, landline, or VoIP.

This matters because:

• SMS can only be sent to mobile numbers
• VoIP lines are often used for spam or fraud
• Landlines may not support texts or auto-dialers

Knowing the types of phone numbers helps you choose the right communication channel and avoid wasting resources.

Conclusion:

Bottom line? E.164 is the global standard that brings structure and consistency to phone numbers. It helps businesses communicate across borders without confusion, ensuring every number is formatted correctly and universally understood. But applying E.164 manually across thousands of contacts? That’s easier said than done.

If you’re ready to simplify global communication and stop wasting time on bad phone data, start using LandlineRemover today. It’s the one tool that does the heavy lifting so you can focus on reaching the right people, the right way.

One tool. Clean data. Smarter outreach.