When was the last time you refilled that account? It sounds like it’s been closed and the number reissued to someone else. A prepaid account is automatically closed if the account balance is $0 for more than 60 days.
Award for Community Excellence 2019 Achiever* *The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.