what to do? what to do?

so i have a paranoid schizophrenic client that changes his phone number every three months due to "people and the government out to get him", don't know exactly that means but he always gets very anxious when he calls me to tell my why he decided to change his phone number. He also usually gives me his new number but this time he hasn't given to me. He, however, keeps calling me asking me to call him back. I have caller id but he doesn't know that and i don't want to tell him either because if he were to find out that i have caller id he would start wondering why i don't pick up when he is calling. He is very very paranoid, paranoid to the point where he doesn't even want to take his psyche meds because "he is sure the doctor is working for the government and she is working with them on killing him". Anyway, if i call him, he is going to ask me how i got his number...he is a very intelligent man and will remember if he gave it to me or not. the man is really something else, but a very sweet individual. he has memorized the ENTIRE bible!!! because "that is the only thing that keeps me sane". so anyway, if i call him and tell him that i have caller id, he will then be too paranoid to call me due to the possibility of me not answering because i wouldn't want to deal with him. if i tell him that he gave it to me and that he probably forgot about it, he will then tell me that it's not true and the government probably called to give it to me. don't know what to do...i guess i'll just have to wait and hope i'm at my desk when he calls next time.