An Optical Line Terminal (2) connected to a Passive Optical Network provides a service to a Client device (1, 8) by receiving its hardware identity, as well as SIM-authentication information, from the Client device, and forwarding to the Authentication Server (3). After authentication of an end-user, a relationship is created between the Client device and the end-user. The OLT activates a service, based on service subscriptions associated with the end-user and on hardware-dependent service definitions associated with the Client device.