a process and device in which 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 , the entering data of b channels being prepared in segments of equal length for b 1 and b 2 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 ; blocks are formed out of entering data of the d channel blocks and fed into the transmission device for transmission to the receiver side ; 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 the received data bits are analyzed . detected d channel blocks are disassembled and fed directly into a code converter , and detected b channel data is decompressed and the binary - coded data converted into coded data specific to isdn .