Have you asked him during times when he's less symptomatic what he wants? Maybe he doesn't exactly know what he wants yet but if it were me it'd go a long way in helping me feel more secure with and likely to approach you for helping me if I were asked directly. If he feels like an active participant in the help and protection you want to offer he may also be more likely to answer his phone or reply to a text even if experiencing paranoia and/or psychosis.

I know fresh cool air and a fast walk helps me calm down.