You can only assign your wireless number to one user ID. If your number is already assigned to an ID, you must delete it from that ID before you can assign it to a different ID. The assigned number must be an AT&T wireless number.
- Go to your myAT&T Profile. Sign in, if asked.
- Scroll to Sign-in info.
- Select Edit or Remove for your Recovery phone
- Edit your details:
- If assigning or changing a number, enter the verification code sent to the number.
- If removing a number, follow the prompts.
    5 . Save your changes