A network system comprising: a lookup unit; a clearing unit having a storage device, the lookup unit and the clearing unit being different from each other; and a client unit being adapted for providing user-related data to the lookup unit, the user-related data being based on user-specific data, the user-specific data being associated with a user, the user-related data allowing for unambiguous identification of the user-specific data, and the user-related data being a first fingerprint of the user-specific data; the lookup unit being further adapted for providing a second fingerprint of the user-specific data to the clearing unit, the second fingerprint being based on the first fingerprint of the user-specific data, the second fingerprint allowing for unambiguous identification of the user-specific data; the lookup unit being adapted for retrieving identification data from the clearing unit by using the second fingerprint, the identification data being associated with the user-specific data; the clearing unit being adapted for retrieving from the storage device the identification data associated with the user-specific data; the clearing unit being adapted for selecting from the storage device the identification data associated with the user-specific data by using the second fingerprint of the user-specific data; the clearing unit being adapted for providing the identification data to the lookup unit; the lookup unit being adapted for retrieving configuration related data for a service provided to the user by using the identification data; and the lookup unit further being adapted for providing the configuration related data to the client unit. a lookup unit; a clearing unit having a storage device, the lookup unit and the clearing unit being different from each other; and a client unit being adapted for providing user-related data to the lookup unit, the user-related data being based on user-specific data, the user-specific data being associated with a user, the user-related data allowing for unambiguous identification of the user-specific data, and the user-related data being a first fingerprint of the user-specific data; the lookup unit being further adapted for providing a second fingerprint of the user-specific data to the clearing unit, the second fingerprint being based on the first fingerprint of the user-specific data, the second fingerprint allowing for unambiguous identification of the user-specific data; the lookup unit being adapted for retrieving identification data from the clearing unit by using the second fingerprint, the identification data being associated with the user-specific data; the clearing unit being adapted for retrieving from the storage device the identification data associated with the user-specific data; the clearing unit being adapted for selecting from the storage device the identification data associated with the user-specific data by using the second fingerprint of the user-specific data; the clearing unit being adapted for providing the identification data to the lookup unit; the lookup unit being adapted for retrieving configuration related data for a service provided to the user by using the identification data; and the lookup unit further being adapted for providing the configuration related data to the client unit.