Security error. This phone has been flashed. What is this?

[garyes]

My ZTE Z667T zinger was on the charger when I looked at it and the screen was lite up with this notice on it; Security Error. This phone has been flashed with unauthorized software& is locked.
My phone is 2 yrs old and has no warranty. T-Mobile said I have to re-install the software for $99. Does anyone know what this is all about?

 

[webworkings]

This will only happen if you have installed unauthorized firmware on the phone. So if your phone only say went up to/accepted "Lollipop" but you tried to force install "Marshmallow" you could get this message. There are other reasons too, like rooting your phone can cause this, but it all adds up to there being stuff on the phone that should not be, and not just apps.

Some carriers/service providers have added this to the phones through them to keep people from rooting and more.