Abstract: A system and method for recording communication data between two communicating users, wherein a switching system is controlled by the recording system via a CTI interface, and instructed to pass digital data directly to the recording system via an S0 interface, provided a connection is established between two of the users to be monitored. Since the communication data is transferred in digital format, it is beneficial to store this data directly on the hard disk of a PC. It is also beneficial if control of the switching equipment is undertaken entirely by the PC for the purposes of call recording.

Abstract: The method and application apparatus establish performance features in a private communication system of a public communication network. Unsuccessful calls coming in from a public communication system to communication terminal apparatuses (KE1. . . n) of a private communication system (KS), as well as calls (ar', ar") directed to private performance feature communication terminal apparatuses (KE-AUL, KE-RR), are acquired in the private communication system (KS) and reported to the application apparatus(PC). Using the application apparatus (PC), a performance feature, for example call forwarding (AUL) or callback (RR), is set up or, respectively, introduced, dependent on the acquired incoming calls (ar', ar").

Abstract: A communications system includes a processor and associated memory containing information identifying dialing authorizations for a plurality of Personal Identification Numbers thereby a user to enter a personal identification number to receive access to authorized connections.

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.