I was getting in "touch" with girls at like 13 so I can't really say they shouldn't, but in all reality, they shouldn't, lol.
My thinking is, if you pay for your phone bill, why not. Otherwise, i'm 99% sure your parents wouldn't approve, and they're the ones paying for your stuff.
A couple side notes somewhat related, I don't think you should be able to be married until 25, and have 2 kids max, lol. Solve our overpoppulation problem like China finally is doing.