The E.164 format is the international telephone numbering standard defined by the International Telecommunication Union (ITU-T). It defines how phone numbers must be written to be uniquely identified globally and used within public telephone networks (PSTN).
By using the E.164 format, calls and SMS messages can be correctly routed to recipients in any country.
E.164 number structure
A phone number in E.164 format consists of the following components:
+ [Country Code] [National Destination Code] [Subscriber Number]
Example:
+447000000000
Where:
- indicates international format;
- 44 represents the country code for the United Kingdom;
- the remaining digits represent the national destination code and subscriber number.
E.164 format rules
According to the ITU-T E.164 recommendation, a phone number must:
- use only decimal digits (0–9);
- start with the + sign;
- contain a maximum of 15 digits, excluding the +;
- include a valid country code;
- not contain spaces, brackets, dashes or other special characters;
- not start with 0 immediately after the +, since no E.164 country code starts with 0.
Correct examples
+447000000000
+336000000000
+40700000000
Incorrect examples
07000000000
00447000000000
+44 700 000 000
(+44)700000000
44-700-000-000
E.164 number examples
| Format E.164 | Country | Country Code |
|---|---|---|
| +447000000000 | United Kingdom | 44 |
| +336000000000 | France | 33 |
| +40700000000 | Romania | 40 |
| +4915000000000 | Germany | 49 |
| +12020000000 | United States | 1 |
The examples above are used for illustrative purposes only.
Why is E.164 important?
The E.164 format is used by most telecom operators and communication platforms for phone number identification and routing.
In SMS campaigns, using this format helps:
reducing contact import errors;
eliminating duplicate numbers stored in different formats;
correctly identifying the recipient’s country;
improving SMS deliverability;
ensuring compatibility with APIs and third-party services.
How do I convert a UK phone number to E.164 format?
To convert a local phone number into E.164 format:
Remove the leading local 0.
Add the country code 44.
Add the + sign at the beginning.
Example
Local number:
07000000000
E.164 format:
+447000000000
Phone number validation
Validating a phone number format does not guarantee that the number is valid or active.
For example, a number may follow the E.164 format but still be deactivated, non-existent or unable to receive SMS messages.
For this reason, phone number validation involves both format checking and verification of existence and availability through dedicated services.
FAQ
What is the maximum length of an E.164 number?
An E.164 number can have up to 15 digits, excluding the “+” sign.
Can I use 00 instead of +?
For maximum compatibility, the E.164 standard recommends using the + sign before the country code.
Is E.164 recommended for importing contacts into NewsMAN?
Yes. Using E.164 format improves contact management and ensures correct SMS delivery across different countries.
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