I have a VM account and phone, and a Sprint account and phone. I purchased three phones (at full price) from VM in 2018 and 2019 in order to use my top up account balances. The phones have never been used. I'd like to use one of the 'new' phones on my Sprint account. When I enter the IMEI #s in Sprint's website, a message appears saying the phones are NOT paid off with Sprint. Why is this occuring? I paid for the phones want to be able to use them.