International phone number normalization (E.164)

Turning a locally typed phone number into one stored form such as +14155552671, with country code included and extensions kept separately.

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What it is

International phone number normalization turns a number entered in a local style into one canonical value, commonly written like +14155552671. E.164 supplies the country-code-based numbering structure and caps the number at 15 digits. Store extensions separately rather than folding them into that value.

Use normalization at the boundary where a number enters your system. A parser such as libphonenumber, the library Google wrote for the Android dialer and open-sourced, needs either an explicit country code or a trusted default region to interpret input such as 020 7946 0958, then it can validate and format the result as +442079460958.

Gotcha: stripping punctuation is not normalization. Without region context you cannot know whether a leading zero is a trunk prefix or part of the national number. A valid E.164 shape also does not prove that the number exists, is reachable, or belongs to the user.

Ask AI for it

Normalize submitted phone numbers with Google's libphonenumber. Parse each value with the user-selected ISO 3166 country as the default region, reject values for which isValidNumber returns false, and store format(number, PhoneNumberFormat.E164) as the canonical phone number. Store any extension in a separate field. Keep the original input only for audit or redisplay, and require SMS or voice verification before treating the number as user-owned.

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