Did you get the phone new or used?
This happens often: you buy the phone used/refurbished, but it's previous usage was a company on an Exchange Server. Companies can buy 3rd party software for their Exchange Server that allows the company virtually infinite control of the phone - delete files, read texts, monitor, wipe clean. kill service.
What happens is sometimes the IMEI number (not the phone number) is left on the Exchange Server and the company sells the phone as out of date.
Then someone else buys the phone and has weird problems with it.
Peace. Alan
Even when I lose, I win.
Galaxy S7Edge [MM6.0.1] Daily Driver
Lumia ICON [Win10M 14965.1001] Hobby