Why do they call high school high school?

At the beginning of High School Musical, why didn't Troy call or see Gabriella the day after meeting her at the New Years party?

• At the New Years party, he told her that he'd call. I don't understand why he couldn't call her.

• Answer:

  For me, this was just like http://en.wikipedia.org/wiki/Grease_(film) in that the leading male is a jock who has a fling while on vacation but has no intention of making it a long term relationship. Of course, HSM is more innocent in that the two leads just shared flirty looks, whereas in Grease it is implied that the two leads had sex over vacation. The parallel continues when Troy discovers Gabriella just transferred to his school (Sandy transferred to Danny's school after summer vacation). I don't think Troy had any intention of calling Gabriella. Sure, he seemed sweet and all during karaoke, but I think he was just having a good time while maintaining his jock/player persona.