In a series of posts on AT&T’s support forums that spans over 40 pages, users on a variety of devices seem to not be able to access their voicemail. This means that this is not a device or OS-specific issue. It also seems to be rather widespread where AT&T users in Arizona, California, Colorado, Florida, Indiana, Nevada, and North Carolina are affect as well.
There doesn’t seem to be a workaround so all users can do right now is to wait. According to AT&T, “A recent software update to some devices may be affecting our customers’ voicemail. We are working with the device manufacturer to issue a patch to resolve this and apologize for any inconvenience this has caused.”
That being said, we’re not sure how many people still rely on voicemail, especially in this day and age where instant messengers are so common, but in case you still rely on it heavily, then we guess you have no choice but to wait it out.