Abstract: A process and device in which (a) data transmission is done so that coded data specific to ISDN is converted into binary code on both a network side and a receiver side using a code converter, (b) the entering data of B channels being prepared in segments of equal length for B1 and B2 channel data in a memory unit and subsequently fed to a transmission device and sent to the receiver side. The data leaving a storage device are checked for consistency and compressed; (c) blocks are formed out of entering data of the D channel blocks and fed into the transmission device for transmission to the receiver side; (d) the ISDN-specific clock pulses are regained out of the temporal sequence of the transferred data bits on the receiver side or net side, respectively, by meant of clock pulse recovery elements; and (e) the received data bits are analyzed.