At present, there are operators which perform a Location Update procedure for a subscriber via Local Number Server under invoice agreement with the subscriber himself, and even where the subscriber is roaming in an area without roaming agreement with the subscriber's operator. In this situation, the subscriber's operator loses revenues because it has no roaming agreements with the operator where the subscriber is roaming, whilst the latter gets revenues from the subscriber by using the subscriber's operator Subscriber Identity Module or newer operator's card. To avoid this situation, there is provided a home location server arranged to determine whether roaming restrictions apply for a home subscriber before providing authentication data for said home subscriber and either deny the authentication data for the home subscriber to the requesting entity or apply a charging or billing for the provision of the authentication data for said home subscriber.