A social networking system comprises a mobile telephone device relating to a first user. that facilitates telephone calls between the first user and other users. User data including identity data and contact data of the other users is initially resident upon the mobile telephone device. The mobile telephone device comprises a resident client application, a social network server and a network providing communication between the mobile telephone device and the social network server. User data is obtained from the device and transmitted to the social network server. The social network server analyzes the user data to identify which other users are also users of the social network server and to form a social network group accordingly and to receive update data relating to any user of the group. The social network server further selects the update data and transmits it to the client application for presentation to the first user.