A method for social networking of mobile devices based upon telephone numbers of the mobile devices includes receiving user profile information and telephone numbers of contacts from a plurality of users' mobile devices; at least one of creating and updating respective user profiles based upon the telephone numbers of the users' mobile devices and the received profile information; identifying relationships among the users based at least upon the contacts contained in the contacts information; and establishing a social network group including at least two of the users based upon the identified relationships among the users.