[header] How to decide whether to call someone [title] Know on what terms you are with the person you want to call. [step] Your relationship with that person is very important in order to make up your mind. [substeps] If you don't get along too well with the person, probably you would feel less tempted to call that person up, while they wouldn't really enjoy hearing from you. 
Don't call them, unless you have something important to talk about with them. Calling them just to chat or to find out something you can find out from tens of other people is inappropriate.