Family Educational Rights and Privacy Act
Schools may release specific directory-type information, including names, address, and phone number, without prior parental consent if the school both provides notification that it reserves the right to release such information and defines what kind of information will be considered directory information. However, under FERPA, parents must be given the right to opt out of directory information release.
Though schools may release directory information without obtaining the prior consent of parents, school officials use their discretion as to whether they should release such information to third parties. More information can be found at the US. Dept of Education's FERPA website.