iPhone voicemail problem: Fix!

Ennie's had a problem with her voicemail on her iPhone. Ever since she upgraded from her 3G to the 3GS it never worked right. Voicemails just would not get pushed to her phone. After AT&T tweaked things even more you couldn't even leave a voicemail!We've gone around and around with Apple and AT&T pointing fingers at each other. Both tried mightily to fix the problem. AT&T spent hours and a couple of SIM cards. Apple doled out a new phone. Nothing worked. Visual voicemail simply refused to function.A restore without restoring the backup fixed things though. We did the restore and things just worked fine after that!I'm guessing that something in the config was hosed up. The upgrade caused some issue somewhere in the system.A clean restore and reconfigure fixed it all.Just something to keep in mind if you run into it.