A Mobile Station (MS), a Base Station System (BSS) and a Mobile Switching Center (MSC) of a cellular network, such as GSM, are disclosed. According to one embodiment, the MS is arranged to carry out one or more security features in its communication with the network. For example, the MS may be arranged to: • by means of information received in a signalling message (0) from the network, discover if the network supports one or more of said security features, • exchange information with the network in order to enable the use of one or more of the above-mentioned supported security features in the communication, • carry out at least one of the one or more of the supported security features in the communication with the network.