United States Phone Numbers: Format, Area Code & Validation Guide - phone-number-standards -

Frequently Asked Questions

Validate US phone numbers by first removing non-numeric characters. Then, check for 10-digit length and a valid area code using a predefined list. Finally, ensure the exchange code doesn't begin with 0 or 1. This multi-layered approach enhances data integrity and prevents common formatting issues, especially when handling user-provided phone number input from web forms or mobile apps.
The E.164 format, such as +17035550123, is the recommended format for storing phone numbers. This international standard ensures compatibility and facilitates data exchange between different telecom systems and applications. Storing the number in E.164 also simplifies tasks like internationalization and number portability checks.
Proper phone number handling ensures regulatory compliance with FCC and state regulations, maintains data consistency across systems, supports number portability, enables accurate international calling, and helps prevent fraud. These practices protect consumers and maintain a seamless user experience.
Number portability allows users to retain their phone numbers when switching carriers. This feature is managed by the Number Portability Administration Center (NPAC), overseen by iconectiv. Applications must integrate with portability lookup services to stay updated on carrier changes and ensure accurate routing.
Validate a Virginia area code by checking it against a list of active and overlay codes, such as 703, 571, 757, 804, 434, 540, 826, 948, and 686. Ensure the list is regularly updated to include new and overlay codes and exclude reserved or inactive ones.
The North American Numbering Plan (NANP) is the numbering plan for the United States, Canada, and 20 other North American territories. It defines the format for phone numbers, including the country code (+1 for the US), area code (NPA), and local number, ensuring compatibility within and between these regions.
Format US phone numbers for international calling using the E.164 format. This includes the plus sign (+), country code (1), area code, and local number. This format ensures correct routing by international carriers and avoids common calling issues.
Valid Virginia area codes include active codes like 276, 434, 540, 703, 757, and 804, as well as overlay codes like 571, 826, 948, and 686. Regularly update your area code database as new codes are introduced or overlay codes are implemented.
Handle number portability by regularly querying a number portability service to check for carrier changes. Update your records with the new carrier information, including the last porting date and portability status, to ensure data accuracy.
Overlay area codes are additional area codes assigned to the same geographic region as existing area codes. In Virginia, examples include 571 overlaying 703, and both are valid. This practice increases the available number pool without requiring existing users to change their numbers.
Implement robust error handling by using a custom error class, such as PhoneNumberError, to categorize different validation errors. This approach allows for specific error messages to be returned to the user, improving the user experience and aiding debugging efforts.
Regularly update your area code database as new codes are introduced or overlay codes are implemented, generally every few months or as advised by resources like the NANPA website. This ensures accurate validation and proper call routing.
No, direct access to the Number Portability Administration Center (NPAC) database is not permitted. However, you can use third-party services that provide the necessary portability information obtained from the NPAC, enabling you to check carrier and portability status.
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