digital signaling on local lines

The ZVEI has specified a variant of the D-channel protocol for the use of ISDN Tk systems in the terminal connection area. This protocol is called DKZ-E and offers some functions that are not supported by the D-channel protocols 1TR6 and DSS1.

The DKZ-E protocol is based on the 1TR6 protocol but has additional features. Since compatibility with the D-channel protocols is ensured, communication between telecommunications equipment with DKZ-E protocol and terminal equipment with the D-channel protocols is possible.