Did you try a search on this community forum to find previous discussions about the iPhone voicemail being full and what you can do to fix it? If not, you should. There are several dozen discussion threads available and many of them have the same basic solution.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Yes, read several articles and followed advice of previous posts and ensured call forwarding was off. Also manually dialed into vm and confirmed there's no current or deleted messages. Never had issue before with multiple messages stored which is reason for post on discussion board. Do you have any specific articles you can point me to troubleshoot further since you're a 'power user'