Phone validation and compliance
What is E.164 format?
Also called: E.164 phone number format, international phone format
E.164 is the international standard format for phone numbers, published by the ITU: a plus sign, the country code, then the national number with no spaces, dashes or leading trunk zero, up to 15 digits in total. Most SMS and calling APIs require numbers in this form.
Numbers are written many ways in a CRM: (415) 555-0123, 07911 123456, +44 (0)7911 123456. Each is ambiguous without knowing the country, and most messaging APIs reject anything that is not E.164.
Converting means knowing the country, dropping the national trunk prefix (the 0 in UK numbers), adding the country code and removing formatting. Doing it with a regex works for one country and fails for the next.
A number in E.164 is well formed. That says nothing about whether it is in service or who uses it.
Example
07911 123456 → +447911123456. US (415) 555-0123 → +14155550123.How SimpleVerifier handles it
Every phone check returns the number in E.164 (phone_e164) with its country, using Google's libphonenumber metadata to confirm the number fits that country's numbering plan.
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Sources
By SimpleVerifier Team · Last reviewed 2026-10-13 · All 50 glossary terms