Abstract: In a communication system (KS), communication terminals (KA) provided for a legitimacy check are allocated to at least one inhibit dial evaluation routine (SWABE). In the framework of a call (ar), the call numbers (zrn) communicated to the inhibit dial evaluation routine (SWABE) as well as the call number (rnr) of the respective communication terminal (KA) are acquired and call numbers (zrn) or, respectively, call number combinations (rnr,zrn) that cannot be evaluated are reported to an application means (PC) via an application interface (acl). The calls (ar) are held in the communication system (KS) until the communicated call numbers (zrn) or, respectively, call number combinations (rnr, zrn) have been checked in the application device (PC) in view of their legitimacy and a legitimacy result (acl-amo) has been communicated from the application device (PC) to the communication system (KS).

Abstract: In a communication system having a function or performance feature to be protected, the periodic transmission of encoded interrogation information is initiated by a security routine to ensure that the function or performance feature is protected. The protected function is activated and further-executed only if reply information which is also encoded is received from a connected crypto-unit in a predetermined time span after a transmission of the interrogation information.

Abstract: Buffer memory systems are utilized in communication systems for the transmission of data that arise irregularly over time. These data are stored in memory areas and are subsequently transmitted block-by-block via a data line. The capacity limit of those memory areas is often exhausted, even though an adequate amount of free memory space is still present in the buffer memory system. A buffer distribution method, which is based on a combination of a fixed and of a dynamic buffer allocation method, solves this problem.