Don't panic. There is probably a good reason. Maybe he was in the server room and couldn't hear the /phone blackberry. My husband has a very similar job and the same happens to us occasionally. There is always a good reason why he didn't call or answer the phone. I usually get very pissed but in the end feel like a fool when there was nothing to panic about. I hope he calls soon to reassure you.
It usually is when he is in the server room.