The cell phone voicemail hacking scandal in the UK made the fact that many cell phone users do not change the default password for voicemail and that spoofing programs could spoof the carrier into identifying that a call is coming from the subscriber and allow access to it.
AT&T did not require a password when subscribers were calling the mailbox from their mobile device because it made it more convenient for people who were traveling and didn't want to punch in numbers to retrieve messages.
Beginning Friday, AT&T began to automatically set the default voicemail setting to
Password Protect on any new subscriber or new line added to an existing
account. In addition, beginning in early 2012, AT&T will set the default
voicemail setting to Password Protect anytime a user upgrades or changes handsets. That means whenever users get a new device, users will be
required to set a password and use it unless you affirmatively turn the
feature off.
AT&T subscribers can who would like to password protect voicemail messages with a 4-15 digit number.
Although AT&T does not recommend turning off your password,
customers have the option of turning the password off via the voicemail
main menu.