What would a girl want to do after giving out her number to a guy who decides to call her?

Let's say a guy and girl hit it off at a party/bar and they seem somewhat interested in each other. The girl gives out her phone number to the guy. The guy want to call the girl, but doesn't know exactly what to do. Should he call her the next day? What will he do with her if he calls her? How does he not make it look like a date out of desperation? This all takes place on a college campus.