E.164 is the international standard for phone number formatting defined by ITU-T. It specifies that a complete phone number should be no longer than 15 digits, starting with a "+" followed by the country calling code and the subscriber number. For example, +14155552671 is an E.164 formatted US number. E.164 is widely used in telecommunications, SMS gateways, and API integrations because it provides an unambiguous, globally unique identifier for any phone number worldwide.

National format is how a phone number is typically written within its own country, often including parentheses, dashes, or spaces (e.g., (415) 555-2671 in the US, or 06 12 34 56 78 in France). International format includes the "+" prefix and country calling code, making it usable from anywhere in the world (e.g., +1 415 555 2671). The international format ensures the number can be dialed correctly regardless of the caller's location, while national format is only meaningful within the number's home country.

Phone number validation checks two key aspects: possibility and validity. A number is "possible" if its length falls within the expected range for that country's numbering plan. A number is "valid" if it matches known number patterns, including area codes, mobile prefixes, and carrier assignments. Our tool uses the libphonenumber library (the same one used by Google and Android) to perform accurate, up-to-date validation against each country's official numbering rules. Validation also detects the number type — whether it's a mobile, landline, VoIP, toll-free, or premium-rate number.

RFC 3966 defines the tel: URI scheme for telephone numbers. It's used primarily in HTML hyperlinks to create click-to-call functionality on mobile devices and VoIP softphones. The format looks like tel:+14155552671 and can include optional parameters like ;phone-context=+1. When a user taps a tel: link on their smartphone, it automatically opens the dialer with the number pre-filled. This format is essential for web developers creating mobile-friendly contact pages and email signatures.

Normalizing phone numbers to E.164 format before storage ensures data consistency, eliminates duplicates, and makes numbers immediately usable for SMS, voice calls, and integrations. Without normalization, the same number might be stored as "415-555-2671", "(415) 555-2671", "+14155552671", or "14155552671" — creating confusion and potential communication failures. Normalization is especially critical for CRM systems, user databases, and any application that sends automated messages or verifies user identities via phone.

Our tool supports all 240+ countries and territories with assigned international calling codes, including the United States (+1), United Kingdom (+44), Germany (+49), France (+33), Japan (+81), Australia (+61), Brazil (+55), India (+91), China (+86), and many more. The underlying libphonenumber library is maintained by Google and updated regularly to reflect changes in national numbering plans, ensuring accurate validation and formatting for virtually every phone number on the planet.

A possible number has the correct digit length for its country but may not correspond to an actual assigned number. A valid number matches known numbering patterns including valid area codes and prefixes. For example, "+1 999 555 1234" might be "possible" because it has the right number of digits for a US number, but it would be "invalid" because 999 is not a valid US area code. Always check for validity (not just possibility) when verifying user-submitted phone numbers for critical applications.