Just a friendly reminder, this is a forum where users help other users. If you are having an issue with your Verizon service, you can use the Verizon Troubleshooters to fix and report issues with your Verizon Phone, Fios TV, or Internet Service, as well as to schedule a repair. You can find these tools that may help you diagnose your issue on the Verizon Residential Support page: http://www22.verizon.com/residentialhelp
Same exact thing happening to me. Worked fine for 5 years until I changed my plan from Unlimited to Pay per minute. The chat help person told me my "phone server is not being identified by the main server and thus failing registration" and said a tech had to come look at it but they always say that.