Is my cell phone de-activated?

I have a 1998 BMW 528i, and the cell phone does not turn on.
It does not do anything when I push the phone button on the
stereo or stearing wheel either. I have checked three fuses that
are referenced in the trunk, but all seem to be okay.
So I was wondering if somehow somebody de-activated it from working
if so I was wondering if there is a way to re-activate the phone.

Thank You ahead of time for the help.