The "Incorrect Password" or "Enter Password" prompt occurs on the iPhone when the password entered is incorrect or never entered at all. Choosing the "Cancel" option is a temporary fix; the prompt will disappear, but reappear randomly at some point. While there is no disable option for the voicemail password on your iPhone, you can prevent the voicemail password prompt from appearing in several different ways. This applies for standard and visual voicemail.
Dial 611 from your iPhone or 800-331-0500 from your iPhone or another phone. It is best to dial from another phone in case there is another issue with your iPhone; the customer service representative may ask you to power off your iPhone to fix the issue.
Input your cell phone number, including area code when prompted by the automated system.
Push "3" to select the “Get Help With Voicemail” option. Select option "3" to reset your voicemail password.
Key in your billing zip code when requested by the system, and you will receive a text message with the new password information. A "Password Incorrect" pop-up will appear on your screen.
Type in the new password. Press OK.
Access "myWireless Account" on the home page and select "Phone/Device" (see References). Click the "Reset Voicemail Password" option located on the right-hand side of the page.
Choose the correct wireless number if more than one phone is on your account. Press "Submit," and a text message with the new password information will arrive on your phone.
Enter the new password information when the "Password Incorrect" prompt appears on your screen. Input the new password and touch "OK."
Push the round "Home" key located on the bottom front of the iPhone. Select the green "Phone" icon.
Tap the "Keypad" icon found between the "Contacts" and "Voicemail" icons. Press and hold the “1” key. The password prompt will appear. Enter your existing password.
Touch the numbers "4," "2" and "1" to change the password. The "Password Incorrect" prompt will appear. Key the new password, and select "OK" to store.
Touch "Settings" from the Home screen. Select "Phone."
Touch "Change Voicemail Password." Enter your current password, then press "Done."
Type new password and select "Done." Retype new password and select "Done."
The password only needs to be entered once after a password reset or change. If you do not remember your password, contact AT&T (see References). If you have never set up a password before, the password is your 10-digit number.