Is your boyfriend cheating if his cell phone is off all the time?

The short answer is: BEWARE. A lot depends on his other behaviour and the quality of the relationship you do have with this person and WHO this person is in terms of overall integrity, but I think anyone who has the mobile phone switched off (or in the car) for much of the time has something to hide. The possibility is that he doesn't want to be disturbed by work related or other calls, but one would think that his phone would be answered by him before you SOME of the time he's with you. Look at his behaviour overall and if things don't seem right to you, don't even bother looking for answers: send him packing and keep the door closed. A tussle over cheating is just not worth the "brain damage" at the end of the day. Be with someone who is open in all respects and whose life is pretty much an open book.