What is E.164 Phone Format?
E.164 is the international telephone numbering plan maintained by the ITU. It ensures every phone number in the world has a consistent, machine-readable structure. If you want to apply that standard to a messy contact export, use the homepage tool.
Quick answer
E.164 is the global phone-number format used by many CRMs, dialers, and APIs. It keeps numbers machine-readable by using a plus sign, country code, and full subscriber number without local formatting characters.
The Structure
An E.164 number contains a maximum of 15 digits and always takes the form:
An E.164 number contains no spaces, no dashes, no parentheses, and no dots. It starts with a plus sign (+) followed directly by the country dialing code and the local number.
Examples:
+14155552671— US number, country code 1+447700900077— UK number, country code 44+4915123456789— German number, country code 49+81901234567— Japanese number, country code 81
Why Platforms Require It
CRMs like Salesforce and HubSpot, dialers like Aircall and RingCentral, and communication APIs like Twilio and MessageBird all use E.164 as their standard phone format. Here is why:
- Globally unique. A number like "555-1234" could belong to any country. "+15551234567" is unambiguous.
- Machine-readable. Systems can programmatically extract the country code, area code, and subscriber number without guessing.
- Routing. International calls and SMS messages require the country code to route correctly. Without it, delivery fails.
- Deduplication. "(415) 555-2671", "415-555-2671", and "4155552671" are all the same number. E.164 normalizes them to one canonical form.
Before and After Examples
| Original Input | Country Context | E.164 Result |
|---|---|---|
| (415) 555-2671 | US (+1) | +14155552671 |
| 020 7183 8750 | UK (+44) | +442071838750 |
| +49.151.23456789 | — | +4915123456789 |
| 0061 2 9876 5432 | — | +61298765432 |
| 07700 900077 | UK (+44) | +447700900077 |
| 800-555-0199 x123 | US (+1) | Needs Review (extension) |
Want to see the same idea in a realistic test file? Use the sample phone import CSV and compare the cleaned and needs-review outputs.
Why Country Context Matters
Many CSV exports contain local-format numbers. "07700 900077" is a valid UK mobile number, but without knowing it is from the UK, a parser cannot safely convert it. It might be mistaken for a different country's format or flagged as invalid.
This is why the normalizer lets you:
- Select a country column for per-row context (handles mixed-country data).
- Set a default country as a fallback for rows without an explicit country.
Numbers without any country context — and without a "+" prefix — will be placed in the Needs Review file rather than guessed at. For the full workflow, see how the phone normalizer works.