German FTZ ISDN Specifications¶

In Germany, the FTZ (Fernmeldetechnisches Zentralamt, part of the government monopoly Deutsche Bundespost) issued a series of technical recommendations (TR) related to all aspects of the telephony and ISDN network.

In case of ISDN, the specifications mainly describe differences to the ITU-T specifications like I.430, Q.921, Q.931 and others.

Originally, in the 1980ies, when interational standardization of ISDN was incomplete, those specifications defined a national ISDN variant. It is basically a fork of early drafts of Q.921 and Q.931.

Later on, in the 1990ies, they switched to Euro-ISDN, also called EDSS1. The differences to ITU-T and ETSI specs obviously were much smaller then.

You can find a collection of such specifications at https://people.osmocom.org/laforge/ftz/

National ISDN (1TR6)¶

TBD

Euro-ISDN (DSS1)¶

TBD