Contact AT&T billing by accessing its website, AT&T.com, or by calling 800-288-2020 for customer service support. AT&T.com offers live chat options and features that allow you to manage your account online after registration.
Access the billing section on the AT&T website by clicking the "My AT&T" tab at the top left of the page to register for an account. Find the link that says "Register Today." This directs to the page where you can select the account you'd like to manage. Choose between wireless, home phone, Internet and TV. Enter your billing account number or AT&T email address and your billing ZIP code to complete registration.