> ## Documentation Index
> Fetch the complete documentation index at: https://docs.invoca.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What Is the Valid Format of Numbers Invoca Can Detect?

> Invoca normalizes and detects phone numbers in standard US and international formats. A number that deviates from these formats won't be recognized as swappable.

Invoca normalizes phone numbers to ensure uniform, accurate handling across the platform. The primary locales supported are the US and the UK.

## US numbers

Valid North American Numbering Plan (NANP) numbers, denoted by country code "1," consistently appear as 10 digits beginning with the area code. Invoca can also handle 11-digit US numbers that include the country code.

Valid US formats include:

* `+1-XXX-XXX-XXXX`
* `1-XXX-XXX-XXXX`
* `1XXX-XXX-XXXX`
* `XXX-XXX-XXXX`
* `(XXX)-XXX-XXXX`

A format that deviates from these — such as `1+XXX-XXX-XXX` — is considered invalid. The Invoca Tag will still find the DOM element, but won't recognize an invalid number within it as valid.

## Numbers from other countries

For countries with different country codes, Invoca applies a standardized format: a plus sign (+), the country code, then the city/area code — which may include a "(0)" if that country sometimes places a "0" before its city/area codes. For example, a valid French number would appear as: `+33 (0)2334444`.

## Where to go next

* [Can the Invoca Tag Swap Vanity Numbers?](/s/article/vanity-numbers-swap)
* [Validating and Troubleshooting Invoca Tags](/s/article/validating-troubleshooting-tags)