What do you really expect to happen? "Hello?" "HI JUSTIN! OH EM GEE, I'M A HUGE FAN OF YOURS AND I LOVE YOU AND YOU'RE THE BEST!" "Who the hell is this?" "MY NAME IS PAUL CHIRO AND I GOT YOUR NUMBER FROM SOME WEBSITE AND I'M A HUGE FAN OF YOURS!" "Well Paul, or whoever you are, I appreciate your fandom, but please don't call me again. Aside from not appreciating being screamed at over the fun, I have my own life to live that doesn't involve bending over backwards for every obsessed fan that some how finds my number. Bye."
I mean seriously, there's a reason why his cellphone number isn't posted all over the internet, because if it was, he would just change his number. If you really want it, probably the only real way to get it would be to stalk him, but that's illegal and thus I express to you that I do not endorse that decision in any way. Furthermore, if you were stalking him, then instead of getting his number, why wouldn't you just talk to him in person? Either way, he's just another human being like everyone else, and he knows that tons of people like him, and you're no different from all of them, and I'm sure he appreciates having his own personal life as you have your own as well. So before you go trying to call him, just think of how invasive that really is, and if you would really appreciate people doing that to you.