The English language has changed greatly over the years. We say "you" instead of "ye" nowadays, and gay means something entirely different than happy. (Not to say gay people aren't happy, you're seen the parades!)
More recently was the introduction of "What's up?" to simply mean "Hello." You often hear a guy greeting another with "Hey, what's up?" and a reply of "Yo, what's up?" No one says how they're actually doing. No "I'm good", no "Comme Ci Comme Ca", no "Shitty, my wife ran away with the dishwasher repair guy."
It's boys that do it more than girls... and dudes are the only ones to do this next one. They have proven that "I'll call you" officially means "goodbye." It doesn't mean he will phone you. It is a direct synonym for "later."
I don't understand it. I'd rather just have you not ask for my number so I can deal with the rejection at that time instead of waiting for 3 days to be rejected. But that's not the way it works.
So remember this ladies! It will save you a lot of wondering. "Talk to ya soon" means "See ya!" And if he's one of the old-fashioned guys that hasn't converted to the new English yet and actually calls then it's a pleasant surprise! :)