I went to listen to a message on my iPhone 6, and instead of showing all my messages when I hit the voicemail tab, it dialed my voicemail, something I haven't dealt with in years. Is this a bug, or a larger issue?
It has to be setup. After several tries to listen to your voicemail, you should receive a window to enter your retrieval code. If not, call AT&T and have them reset your voicemail.