This article will teach you how to establish the phone country code for your users.
The initial action to take is to go to wp-admin -> Listivo Panel -> User Panel -> User. You can also set the default country code - it works for already existing numbers. If your users didn't add a country code, it would add to their numbers.
The country code is based on the user's IP address. The user can change want to.
After registration, users can change it on account settings.