Apparatuses and methods are provided by which a second address of user equipment, which is served on a first address in a first network in a first address realm, to be used by the user equipment for a service in a second address realm is detected, the second address is stored together with the first address, and a network policy control element controlling policy in connection with the service in the second address realm is informed about the second address is. In this way, also a single stack user equipment may access services in different address realms.