E.164 is the international telephone numbering standard defined by the ITU-T. It ensures that every phone number is globally unique and can be correctly routed across public telephone networks (PSTN).
It is widely used by telecom operators, SMS platforms, and communication APIs.
E.164 number structure
An E.164 number follows this format:
+ [Country Code] [National Number]
Example:
+447000000000
- + indicates international format
- 44 is the country code for the United Kingdom
- the rest is the subscriber number
E.164 rules
According to ITU-T E.164:
- only digits (0–9) are allowed
- must start with +
- maximum 15 digits (excluding +)
- must include a valid country code
- no spaces or special characters
- no leading 0 after country code
Correct examples
- +447000000000
- +447111111111
Incorrect examples
- 07000000000
- 00447000000000
- +44 700 000 000
- (+44)700000000
E.164 examples (UK localized)
| Format | Country | Code |
|---|---|---|
| +447000000000 | United Kingdom | 44 |
| +447111111111 | United Kingdom | 44 |
All numbers are fictional.
Why is E.164 important?
- improves SMS deliverability
- reduces contact import errors
- prevents duplicate records
- ensures correct country routing
- improves API compatibility
How to convert a UK phone number to E.164
- Remove leading 0
- Add country code 44
- Add + at the beginning
Example:
Local number: 07000000000
E.164: +447000000000
Phone number validation
A number may be correctly formatted but still invalid or inactive. Format validation does not guarantee deliverability.
FAQ
Max length?
15 digits excluding +.
Can I use 00 instead of +?
Technically yes, but + is recommended.
Required in NewsMAN?
Yes, for SMS imports and campaigns.
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