How do I turn the phone OFF to save battery?

[Jedi]

i have the xv6700 with WM6.1 (build 19213).

I sometimes work in the sub-basement, and i get no signal. the phone constantly searches for signal, thus draining my battery. My fully charged battery got drained in ~6hrs because of this

when i press the OFF button, it apparently just puts the phone to sleep. it will still take incoming calls/txt msg, and (apparently) search for signal.

How do i make the phone really turn OFF?

THX