Abstract: A method of making network services available to a subscriber of a first mobile communications network when the subscriber roams in a second mobile communications network. The method includes: intercepting a signaling message issued by a service switching function of the second mobile communications network as a consequence to a service request by the subscriber; checking the intercepted signaling message; and based on the check, updating the intercepted signaling message so as to include service addressing data adapted to invoke a service in the first mobile communications network.