FTZ 1 TR 6

FTZ 1 TR 6 ( short 1 TR 6) is the signaling protocol (D channel protocol) of the National ISDNs the former German Federal Post Office, Telecommunications Technical Central Office (now the German Telekom ); it was first used in 1989. was replaced for all new connections through the DSS1 protocol.

The active marketing lines of the National ISDN is already set mid-1990s; the operation was finally stopped after several extensions at the end of 2006. Customers of Telekom AG, which still had connections of the National ISDN, was terminated at the end of the use in September 2006. The terminated connections have been converted at the latest on the night of 28 to 29 December 2006 forced to DSS1. This change to DSS1 was free for the customers, but the affected participants had to purchase new terminals in the rule.

Within private telephone systems will probably still exist long time a protocol variant ( FTZ 12 TR 7).

Number system

1 TR 6 does not support MSN, but used terminal selection digit ( EAZ ). ISDN customers were given a block of 10 consecutive numbers with last digit from 0 to 9 These final numbers are the EAZ. The EAZ " 0" is used for calls that are to be signaled simultaneously on all connected terminals ( "global call" ). At 1 TR 6 it was not possible to reuse existing ( analog ) telephone numbers.

Equipment selection

When an incoming call, a broadcast message is sent to all devices. The message includes compatibility requirements. These are:

  • Connection indicator (for compounds from a non-ISDN network)
  • Transmission service ( services such as voice, data)
  • Terminal selection digit ( EAZ ), or possibly a subaddress extension number
  • Requirements for OSI layers 1 to 7 ( transmission rate, data backup, etc.)
  • ISDN number

The one device that meets these requirements, must take the call.

A device selection using the terminal selection digit ( TSD ) is also possible. Each device may have a EAZ 1-8. In the broadcast message then the EAZ of the desired device is included. Each device compares its EAZ with that in the broadcast message. If they match, it accepts the call. However, the network operator must be aware that the devices have a set EAZ.

Semi-permanent connection

A special feature of 1 TR 6 is the semi-permanent connection (SPV ), which was later renamed in Pre-ordered Dauerwählverbindung ( VDV). This is a dial-up connection to a predetermined interconnection partners, who will be paid on a lump-sum compensation. This service was very popular in Germany because he had similar features of a dedicated line, but was offered a lot cheaper. Since the service at Euro -ISDN is not available, asked many participants not to it, or continue to explicitly ordered 1 TR 6, to continue this service.