direct data line
The direct data connection (DDV) is a form of leased line. It differs from the standard fixed connection(SFV) in that it is more reliable and is monitored by the network operator so that the operator can switch to a substitute connection in the event of a fault.
In the case of the direct data link, two main connections with a digital connection point, which can be used for their own needs for the transmission of any form of communication, are connected to each other via fixed lines. In the past, these connections were called HfD, which stands for Hauptanschluss für Direktruf, but now they are called DDV.
DDVs are characterized by high availability and lower error rate of `10^-6` compared to monopoly transmission paths. The transmission is generally based on the synchronous method.