You will break many hearts, my dear.
Guys, especially guys who are into you in a big way, are nearly as phone- text- and email- obsessed as a human can be. The only thing that tops "waiting for a new girlfriend to call you" on the scale of waiting-ness is "waiting for the test results." And even then, I'd probably put my cancer doctor on the other line if my girl was calling. I mean, the test results aren't going to CHANGE, right?
Guys are just as capable of any other higher life form of reading into things, wondering what you're thinking, wondering how what we're thinking reflects on what we think you're thinking, and other fractal-like manifestations of the hell that is sentience. We may not show it--or at least, our Dads all told us not to--but you not calling the next day can plain rip our hearts out.
Now, this is all assuming the guy is really into you, in a romantic way. If it was just a sex thing for the guy, he'll likely be equally phone-obsessed, but mainly about whether he may have accidentally given you his real number instead of his decoy number while passionately drunk.
Personally, I hate "just chatting" on the phone, no matter who's on the other line. I'm a goal-oriented phone user. But that's absolutely not true when I'm courting a lady. Wooing is a weird netherworld, when the normal rules are thrown out in favor of doing "whatever will get her in my presence again."
So if you like this guy, let him know it. It can't hurt to put some more good vibes out into the world, right?