Deactivated phone still able to access Sprint 4GLte network

[AC Question]

My older Samsung S3 phone was removed from my Sprint account and deactivated. Although phone operations are no longer possible, the phone is still able to connect to Sprint's 4GLte network and access the internet (not a local WI-FI network connection, but an actual connection on Sprint's Lte network ). The S3 doesn't use a SIM card, so that is not the issue. Sprint's customer support doesn't understand why the connection is still active, but they have assured me that any of the phones data usage won't be added to my account - not sure I can believe them. Can anyone tell why the phone is still active on the network and how it can be removed ?