EASY FIX. Called Verizon. Tech support said they have been getting this a lot with the new iOS update.
- Settings - > Phone - > Change Voicemail Password
- Enter new PIN twice and it should save.
- Go to Home screen.
- Call *86.
- Prompt will ask for voicemail PIN. Do NOT enter it. Just hang up.
- Problem solved.
Tech said this works 100% of the time! Worked for me as I immediately tested it from my landline. He said something that by entering new PIN and then calling and hanging up you are bumping the system so it knows you are there. Or something. I didn't really care so long as it worked.
Cheers!