This module will add a telephone field to addresses, useful when you want a contact telephone number for shipping addresses either for you or for your courier.

As you would expect the module adds a telephone field to both Billing & Shipping (since opencart address book is a one stop list).

But on checkout register / billing or guest billing pages will show the telephone field with account information (only once) and then use that phone number for the address entry - everywhere else you will see a telephone field as part of the address form (customer edit addresses, admin panel edit addresses etc).