You can, as long as the phone has power, you can still turn it on and look at your contact list. According to DN she was manually transferring the numbers from her old phone (with broken speaker) to the new plain jane phone.
What I find interesting, is that he says she transferred service on Sunday. That does make sense because their service wasn't restricted yet. However, it means that if somebody took those phones, they were playing with the plain jane one and not her older, nicer phone. I wonder what kind of phone Jeremy had? I also think since DB was manually transferring her numbers, it seems more likely that she could have dialed a number she never had dialed before, one that was in her contacts, but she had never called before.