Question: how long should you wait to call a girl after getting her number?
Answer: If you're really into a girl, do not let more than 3 days pass before initiating some sort of contact, even if just to say 'hi' briefly... call, text, email, gchat, facebook, skype, tweet, BBM, comment on her blog, send a carrier pigeon -- something. Don't ask girls out on dates via text message.