About messages from the AT&T online registration process
If you are trying to register for an online account, but are getting a message that says that telephone number is already in use, this means the telephone number is already registered in an online account.
It may be possible that you or someone else in your business already set up a User ID for this telephone number. Try the 'Forgot User ID/Password?' link found on the Sign In page and follow the directions given there.
If you continue to have difficulties, contact us and describe the situation. Be sure to include as much information as possible: your billing telephone number, your User ID, your current email address, and any previous email addresses.