If you use the teephone module, than this is a handy one...It checks the number of digits in the context of the country code. It validates the amount of numbers. It does not check whether the number exists or not!
It works perfect when i tested it with some local and mobile phonenumbers.
It looks at the E164 codes: https://en.wikipedia.org/wiki/E.164
Install it with composer and enjoy the third party installations...(composer require drupal/telephone_validation)
This is the number of the Louvre in Paris.
This input is correctly not accepted.