You can select between U.S., Australian, or custom format phone numbers.
Custom format phone number allows you to specify the format you want. You can include a country code, parentheses, spaces, or dashes.
Phone number questions allow various formatting options, including:
No format (equivalent to not choosing a format)
US Phone Number
AU Phone number
For all formats except "no format" the form will automatically enforce that the input matches the specified format. That is, forms perform validation – if the format is not met, respondents may not proceed to the next page and may not submit the form.
Validation here does not mean that the phone number is checked and determined to be an active phone number. It only means that it adheres to the specified format.