i have a thought!!it may sound dumb but it makes sense.you know how sometimes phoebe's in the underworld and her phone rings and stuff and she goes "you gotta admire the range"(love that quote),well in the episode All Hell Breaks Loose,Leo couldn't be contacted because he was in the underworld,so why didn't he bring a phone,so one of the sisters would call Leo and he'd be on time to heal Piper and Prue!!!!is that dumb?