Hello, 68Z. Thanks for contacting us. We'll be happy to explain this further. As Sprint continues to enhance our network with improved features and functionalities for our customers, it was identified that several of them continue to have very aged devices.
These devices are 6+ years old and have certificates that will soon be expiring. This certificate expiration is an industry decision, not a Sprint decision.
In this case, the devices that are already active will continue to work, however, may experience service degradation when updates are required.
Unfortunately, we no longer sell devices compatible with the PayGo plan as it's sales expired. We suggest you access our website to see the devices and plans currently available. Here is the link: https://www.boostmobile.com/.