How to write phone numbers in international format (E.164)

Correct international format improves carrier, country, and region lookup accuracy.

Quick rule: Start with +, then country code, then national number. Example: +12125551234.

What is E.164?

E.164 is the global standard for international phone numbers: a leading plus sign, country code, and subscriber number — without local trunk prefixes.

Examples

United States: +1 212 555 1234
United Kingdom: +44 20 7946 0123
Australia: +61 2 9876 5432

Spaces are optional. Compact forms like +12125551234 also work.

Common mistakes

Missing country code (e.g. 2125551234 without +1).
Keeping a domestic leading 0 in international input.
Unusual separators that break parsing.
Copy-paste from contacts without checking the leading +.

Why it matters for lookup

The same local digits can exist in multiple countries. Country code is required to identify the correct numbering plan. Try the free carrier lookup or browse country calling codes.