What is E.164 phone format?
E.164 is the ITU-T standard that defines how phone numbers should be formatted to be universally routable. The format is a plus sign, a country code, and the national number, with no spaces, no dashes, no parentheses. "+14155550100", not "(415) 555-0100".
The rules
Maximum 15 digits including country code. No leading zero on the national portion. No formatting characters. The plus sign is the prefix that signals "this is E.164" so it can be distinguished from national-format numbers that happen to start with digits.
Examples
+14155550100 (United States). +442071234567 (United Kingdom). +81312345678 (Japan). +5511987654321 (Brazil). The country code can be one to three digits; the rest is country-specific. Most national numbers are seven to ten digits.
Why E.164 for storage
Always store phone numbers in E.164. Always. Pretty-printing for display is a render-time concern. Storing display formats ("(415) 555-0100") makes lookup, deduplication, and international routing painful. Convert at input, store E.164, format at output. message.com's APIs accept and return E.164 throughout.
See it working on message.com.
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