International phone number format: +, country codes and E.164

What belongs in the number?

The plus sign marks international format. The country code identifies the numbering plan, followed by the national number. Spaces can make a contact easier to read, while an online form may request digits only or separate the country selection.

International access prefixes such as 00 or 011 are dialing instructions used in particular places; they are not the same as the number's country code. A plus-format contact is usually easier to reuse while traveling.

Handle the leading zero correctly

• A national trunk prefix is often removed in international format: the UK prefix 020 becomes +44 20, and Japan's 03 becomes +81 3.
• Do not remove every leading zero as a universal rule. Italy's geographic numbers retain their initial zero after +39.
• Copy the full assigned number from your account and follow the relevant national numbering plan.
• Treat an extension as a separate instruction or field, not extra digits appended to an E.164 number.

Enter a number in an online form

1. Check whether the form already has a country selector or country-code field.
2. Enter the remaining digits in its requested format, avoiding a repeated country code.
3. Remove formatting characters only when the form requests it; keep meaningful national digits.
4. Review the complete destination before calling, texting or saving the contact.

Format does not prove availability

A correctly written number is not proof that it is assigned, active, SMS-capable or controlled by the person entering it. Country and area codes also do not reveal every feature of a virtual number.

For Blacktel, check the actual selected number's capabilities and active status separately. Use the displayed full number when sharing contact details, and check the recipient's country carefully when sending.

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