Oh wow! I can certainly understand your frustration with your voicemails not working. Voicemails are very important, so lets get this fixed! The Iphone 4S uses Visual Voicemail to access your voicemails http://bit.ly/qVR66Q. Does the error message pop up on the Voicemail screen when you hit play? Try a Soft Reset of the device http://bit.ly/tXe7I4. Keep me posted.
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