Abstract: A method of arranging data protection in a telecommunication system including a first mobile communication network, a second mobile communication network, and a mobile station supporting both of the mobile communication networks is disclosed. The method includes ciphering traffic between the mobile station and the first mobile communication network using a first cipher key; calculating a second cipher key to be used for ciphering traffic between the mobile station and the second mobile communication network in the first mobile communication network when the mobile station operates in the first mobile communication network; transmitting information necessary for calculating the second cipher key from the first mobile communication network to the mobile station when the mobile station operates in the first mobile communication network; and calculating the second cipher key at the mobile station to be used for ciphering traffic between the mobile station and the second mobile communication network.

Abstract: A method and system of offering wireless telecommunication services in a visited telecommunication network for a terminal device which does not have a first identifier accepted by the network. In the method, the visited network gives the terminal device a right to a temporary use of a telecommunication connection and establishes a connection with a third party in order to obtain a confirmation of paid services, for example. The third party checks a second identifier transmitted by the terminal device and transmits the confirmation to the visited network, which offers telecommunication services for the terminal device.

Abstract: Disclosed is a method for performing an inter-system handover. The method triggers the handover of a mobile station (100) from a UTRAN system to a GSM system by sending a HANDOVER FROM UTRAN COMMAND message from the UTRAN system. For the case where a HANDOVER COMMAND is sent transparently with the HANDOVER FROM UTRAN COMMAND, where the HANDOVER COMMAND has an information element set for indicating that ciphering is to be started, the method begins data ciphering immediately after handing over to the GSM system such that the first data frame transmitted by the mobile station in the GSM system is a ciphered data frame. For the case where there is a pre-existing UTRAN system ciphered data connection when the HANDOVER FROM UTRAN COMMAND message is received, the method continues without interruption the use of data ciphering with the data connection after handing over to the GSM system.

Abstract: An object of the invention is a call control method for user equipment which can be in connection with more than one radio system. The user equipment is under a first radio system. In the method, a first system detects that there is a need to transfer data to the user equipment. A paging message is transmitted from the first radio system to the user equipment, the message containing a command to move over to the cell of a second radio system. Reselection of the cell is started in the user equipment on the basis of the message.

Abstract: Disclosed is a method for performing an inter-system handover. The method triggers the handover of a mobile station (100) from a UTRAN system to a GSM system by sending a HANDOVER FROM UTRAN COMMAND message from the UTRAN system. For the case where a HANDOVER COMMAND is sent transparently with the HANDOVER FROM UTRAN COMMAND, where the HANDOVER COMMAND has an information element set for indicating that ciphering is to be started, the method begins data ciphering immediately after handing over to the GSM system such that the first data frame transmitted by the mobile station in the GSM system is a ciphered data frame. For the case where there is a pre-existing UTRAN system ciphered data connection when the HANDOVER FROM UTRAN COMMAND message is received, the method continues without interruption the use of data ciphering with the data connection after handing over to the GSM system.

Abstract: A method and system of offering wireless telecommunication services in a visited telecommunication network for a terminal device which does not have a first identifier accepted by the network. In the method, the visited network gives the terminal device a right to a temporary use of a telecommunication connection and establishes a connection with a third party in order to obtain a confirmation of paid services, for example. The third party checks a second identifier transmitted by the terminal device and transmits the confirmation to the visited network, which offers telecommunication services for the terminal device.