The present invention relates to a method for operating a RF communication device, a RF communication device (400), a method for operating an authentication server of a network entity and to corresponding computer programs. All aspects of the present invention take into account that a continuous operation of a RF communication device, in particular of a metering application, needs to be ensured, even if the function of a component SIM or initial SIM (410) has to be replaced or supplemented by an external new SIM (420). It is suggested to ascertain the validity of the external SIM by using information stored in the component/initial SIM. The validity of the external SIM can be ascertaining either solely on the side of the RF communication device or by sending a corresponding validity check request signal to a remote network entity.