International phone number format, without the guesswork
Understand plus signs, country calling codes, trunk prefixes, and the formatting mistakes that stop calls from connecting.
The reliable pattern
The safest portable format is a plus sign, the country calling code, and the national significant number. This is often called E.164-style formatting. A complete number might look like +33 1 84 80 20 20, though spacing is for readability and is not part of the routed number.
Why the plus sign matters
The plus sign represents the international access prefix used from your location. It avoids making you memorize whether a network expects 00, 011, or another prefix.
Country code versus local prefix
A country calling code identifies the destination country or numbering zone. A domestic trunk prefix is used only for calls placed inside that numbering plan. When converting a local number to international format, the trunk prefix is commonly removed—but rules vary, so confirm against an authoritative numbering source or the recipient.
Common reasons a number fails
- The country calling code is missing.
- A domestic leading zero was kept when it should have been removed.
- The number was copied with an extension that the dialer cannot interpret.
- The route is emergency, premium-rate, satellite, sanctioned, or otherwise unsupported.
- The number is incomplete or has been disconnected.