An apparatus comprising means for performing: sending, to a network entity, a Network Function Discovery request comprising parameter information; and receiving, from the network entity, a response to the request, the response comprising: at least one identifier for at least one Network Function service producer; and at least one of: information ranking the at least one Network Function service producer according to how well the at least one Network Function service producer matches the request; and an indication of how much of the parameter information is matched by one or more parameters of the at least one Network Function service producer.