Method for producing a coding rule

摘要

In a telecommunications network, especially a cellular mobile-radio network, it is intended to produce a coding rule which is used for the selection of one of a plurality of codes which are to be kept secret and are stored with the subscribers. Since at least one control centre always transmits different signals to all the associated subscriber apparatuses for operation handling, irrespective of the direction in which the connection is set up (initiated by the subscriber apparatus or arriving at said apparatus), according to the invention, these signals are subjected in all the subscriber apparatuses to additional evaluation with respect to the number and type of signalling processes within an agreed time interval. The result is then used as a coding rule. Its transmission remains concealed from an unauthorised user. <IMAGE>