Telwidget validation provides validation to telwidget for textfield.
It uses Telephone Validation module to validate a phone number.

For more information see a Telephone Validation.

Installation

Install Telephone Validation.

After install and setup Telephone Validation and libphonenumber-for-php, you can just install this module and configure field instance settings.

Requirements

textfield max length must greater than 20.
If textfield has max length less than 20, Validation will not work.