How to tell dad he can't have a phone to use while in rehab/SNF?

My dad has moderate dementia and STML. This is the second time in rehab within 2 months. The first time he was there he had a phone, but the only time he used it was to call me or my sister to complain about something or to tell us something like his throat hurts. We always ask if he told the nurse and he says yes, but they're taking too long. Or something similar...once he told my sister that if we call the nurse they will respond faster. He forgets he is not the only patient in rehab. He calls at all hours too!! He never calls just to visit with us. 
So this new stint in rehab for a fracture, we told the staff he is not to have a phone, but is to use his call button to call the nurses. We explained to staff why we don't want him to have a phone. Anyway, he had the nurse call me last night so he could talk to me and he asked me where his phone is. I was able to skirt around the answer, but I'm afraid he will ask me again. I can't tell him the truth....so I need help on how to tell him there is no phone. He knows he had one before which is why this is tricky.