The E.164 international format, in one line
+ <country code> <subscriber number> - digits only, no spaces or brackets, 15 digits maximum. That is the entire E.164 specification, and it is the only format you should store, transmit, or send SMS to.
Examples: a London landline written locally as 020 7946 0958 becomes +442079460958. A New York mobile written locally as (415) 555-0132 becomes +14155550132. The leading zero or 1 is a national trunk prefix; it is dropped when the number is written in international form.
Dialling from a phone: + or the exit prefix
From a mobile, dial + followed by the country code and the subscriber number - the network substitutes the correct exit prefix automatically. From a landline you may need to dial the literal exit prefix instead:
- 00 - UK, Ireland, most of Europe and Africa
- 011 - United States, Canada, and the rest of the North American Numbering Plan
- 0011 - Australia
- 010 - Japan (varies by carrier)
Worked examples
| Country | Code | National | E.164 |
|---|---|---|---|
| United Kingdom | +44 | 020 7946 0958 | +442079460958 |
| United States / Canada | +1 | (415) 555 0132 | +14155550132 |
| Germany | +49 | 030 901820 | +4930901820 |
| France | +33 | 01 70 18 99 00 | +33170189900 |
| Australia | +61 | (02) 8123 4567 | +61281234567 |
| India | +91 | 022 6789 1234 | +912267891234 |
| United Arab Emirates | +971 | 04 123 4567 | +97141234567 |
| Singapore | +65 | 6123 4567 | +6561234567 |
Formatting for SMS and APIs
Always send SMS, WhatsApp, and API calls in E.164. Aggregators reject nationally-formatted numbers, and CRM deduplication breaks the moment two systems disagree about how to render the same number. If your form accepts free-text phone numbers, normalise to E.164 server-side with a library such as libphonenumber before storing it.
Frequently asked questions
What is the international phone number format?
The global standard is E.164: a leading plus sign, the country code (1 to 3 digits), and the subscriber number, with no spaces, dashes, or brackets. The total length is capped at 15 digits. For example, a London landline written nationally as 020 7946 0958 becomes +442079460958 in E.164.
How do I dial an international phone number?
Replace the local trunk prefix (such as the UK 0 or the US 1 long-distance prefix) with the international exit prefix of the country you are calling from - 00 in most of Europe, 011 in the US and Canada - followed by the destination country code and the local number. On a mobile phone you can simply use + instead of memorising the exit prefix; the network substitutes the correct one for you.
What is an international exit prefix?
An exit prefix (or IDD prefix) is the sequence you dial to tell your local network the call is leaving the country. Common ones: 00 (UK, most of Europe, Africa), 011 (US, Canada), 0011 (Australia), 010 (Japan). Using + in place of the exit prefix is universally supported on mobiles and on most VoIP systems.
Why should I store numbers in E.164 format?
E.164 is unambiguous - the same string works for voice, SMS, WhatsApp, CRM lookups, and CDR reconciliation, from any country, on any network. Storing numbers nationally (with leading 0s, spaces, or brackets) breaks portability and causes failed deliveries when calls or messages cross borders.
How do I format a number for SMS?
Always send SMS to the destination number in E.164 (leading +, country code, subscriber number, digits only). Most SMS APIs and aggregators reject or silently drop messages addressed to nationally-formatted numbers, especially for cross-border traffic.
What about toll-free and non-geographic numbers?
Toll-free and non-geographic ranges (UK 0800, US 1-800, etc.) still follow E.164 once you include the country code: a UK 0800 123 4567 becomes +448001234567. Note that many toll-free ranges are only reachable from inside the country of origin - check coverage before publishing them internationally.
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