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connection to a private network. The signalling protocol is handled by an IPH, DTU-PH, DTU-
BA, DTX-I. The DTU-VC can be used for DPNSS as well, but is only suited for voice
connections.
For determining if the related users in both networks are compatible, a special parameter is
transferred over the DPNSS No.1 link with incoming or outgoing calls. This parameter is the
Service Indicator Code (SIC). The SIC is a two byte code which is derived from the IBSC of
the ISPBX internal party. The SIC can be assigned as voice or data together with some
additional values for data such as speed and parity.
-
For an incoming call, the SIC is translated into an Internal Service Identifier (ISI). The ISI
comprises an Internal Service Identification Code (ISIC) and an Internal Basic Service
Category (IBSC). The ISIC is passed through to the destination port. The IBSC is used for
compatibility determination.
-
For an outgoing call, the calling port supplies an ISIC, which together with the ports IBSC
form an ISI. The ISI is translated into a SIC and passed over the DPNSS No.1 link.
The translation tables used are given in appendix A.
For more information on the routing aspects and on the Service Indicator Code: see Facility
Implementation Manual; Networks and Routing.
3.3.4.
1TR6 Route
A 1 Technische Richtlinie 6 (1TR6) link is used for connection to a private or a public network.
The link can be either:
-
A 2Mbps line, 30B+D (timeslot 16 is used for signalling, timeslot 0 is used for
synchronisation). This requires a DTU-PH which handles its own signalling protocol.
-
A 192kbps line, 2B+D (16kbps D channel used for signalling, 48kbps overhead). This uses
a DTU-BA or DTX-I. The signalling protocol handled is by the DTU-BA or DTX-I.
For determining if the related users in both networks are compatible, a special parameter is
transferred over the 1TR6 link with incoming or outgoing calls. This parameter is the 1TR6
Service Indicator (1TR6-SI). The 1TR6-SI is a two byte code which is derived from the IBSC
of the ISPBX internal party. The 1TR6-SI can be assigned as voice or data together with some
additional values for data such as speed and parity.
-
For an incoming call, the 1TR6-SI is translated into an Internal Service Identifier (ISI). The
ISI comprises an Internal Service Identification Code (ISIC) and an Internal Basic Service
Category (IBSC). The ISIC is passed through to the destination port. The IBSC is used for
compatibility determination.
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