I updated to iOS 5.1.1 today, and now the voicemail button on my phone calls Sprints old, audio voicemail system. I no longer have access to visual voicemail.
I suspect that the feature may have been disabled for Sprint users because previously, I was finding Visual Voicemail to be very unreliable, resulting in delayed receipt of voicemail messages, and frequently, messages appearing in the list, but being unable to be played without restarting my phone. (The message would show up in the list with a duration of 0:00 until the phone was rebooted.)
Was the feature disabled for Sprint users, or did the update just break Visual Voicemail in some other way? How can I get it back?