| 摘要 |
The invention provides a method for protecting a transmission line between a first station and a second station, via which transmission line signalling information, such as dialling information, and/or user information, such as voice, can be transferred. The method comprises a verification step (I) in which the identity of the second station is verified on the basis of challenge response, and a signalling (III) step in which signalling information, such as dialling digits, are transferred via the transmission line in an enciphered manner. In this context, enciphering of the signalling information occurs on the basis of cipher information, which is transferred during the verification step. Preferably, only the signalling information is enciphered and between the verification step (I) and the signalling step (III) a transition step (II) is carried out in which, inter alia, an additional verification takes place. The invention further provides a device and a system in which the method is used. <MATH>
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