Voicemail Unavailable Could not authorize access."
When setting up my Voicemail on my new Verizon iPhone 5 I got this error.
"voicemail unavailable could not authorize access."
The fix was to turn off my phone, have Verizon reset my VM, turn the phone on, then call into the VM from the phone using *86 and use the Verizon setup menu. Once this was done I kill the phone app on my iPhone and I could then get into VM. Hope this helps.
iPhone 5, iOS 6, Verizon