U interface

The U interface is the interface on the local loop between the local exchange and the network termination in the ISDN network. The designation "U" is from the ISDN reference model, in which there are reference points S, T, U and V and the corresponding interface definitions.

While UK0 is the name for this interface on the base terminal, UK2 and UG2 are those of the Primary Rate Interface.

For the connection of ADSL modems, there is the U- ADSL interface. It is the interface between the local exchange and the splitter.

In analogy to this designation form has the extension technique for such interfaces, but in other technique chosen similar designations, for example Up0 and UpN.

Europe for the U- interface are standardized physical and electrical specifications so that it is possible to switch network termination (NT) from different manufacturers. In ADSL, however, this is not (yet) the case, the U- ADSL specification of Deutsche Telekom, although generally available, but is only valid in Germany.

• ISDN