Editing FTZ 1 TR 6

{{Unreferenced|date=December 2009}}
'''FTZ 1&nbsp;TR&nbsp;6''' (or '''1 TR 6''') is the standard for the obsolete [[Germany|German]] national [[Digital data|digital]] signalling protocol ([[D channel]] protocol) used for the [[Integrated Services Digital Network|ISDN]]. It has been superseded by [[DSS1]] but is still in use on some lines and [[Private branch exchange|private exchanges]].

1&nbsp;TR&nbsp;6 did not support [[Multiple Subscriber Number|multiple subscriber numbers]] but featured an ''Endgeräteauswahlziffer'' (''EAZ'', German "user device selection digit"). ISDN subscribers would get a sequence of 10 subsequent subscriber numbers, the last digit of which being the EAZ. The EAZ "0" was used for "global calls" to all connected devices.

1&nbsp;TR&nbsp;6 also offered ''semipermanent connections'', which were (comparatively cheap) [[leased line]]s that could be temporarily disabled to use the [[B channel]] for other purposes.

It is said that the "TR" simply stands for "technische Richtlinie" (technical guidelines).

==External links==
* {{Citation | url = https://osmocom.org/projects/retronetworking/wiki/German_FTZ_ISDN_Specifications#National-ISDN-1TR6 | type = list | title = Scanned FTZ 1 TR 6 specifications, published in Osmocom retronetworking wiki. | publisher = Osmocom}}.

{{DEFAULTSORT:Ftz 1 Tr 6}}
[[Category:Integrated Services Digital Network]]