This question collects valid phone numbers from the responder. If the responder's input is not in the expected format, there will be an error message prompting to user to enter in a valid phone number.
The answer to the number question is stored as number data type.
Showing input mask
By enabling Show input mask, you can format the input from the responder as (000)-000-0000 when they are entering their phone number.
International phone numbers
International option allows the responder to enter in numbers outside of the U.S. phone format. If you enable this option, the responder will be able to choose from a list of countries and their respective prefixes (+90, +1, etc.).
If you would like to change the default country phone number, you can enable the Default country option and pick a country from the menu.