5.13.1. Direct Dialing In (DDI) 
DDI enables users to call parties in private ISDN networks directly
via public ISDN using the ISDN numbering plan. The ISDN exchange sends
the DDI number to the private ISDN. The DDI number consists either of
the complete ISDN number (country code, area code and subsciber number)
or part of it, the minimum being the subscriber number. Which parts are
transmitted varies from one exchange to another. The discriminating digit
sequences for national and international calls (e.g. 00 and 0 or 16 in
France for inter-zone calls) are not part of the DDI number and are therefore
not provided by the exchange. The following components of the home ISDN
NUMBER must always be specified in connection with EURO-ISDN trunk circuits:
- Country code (e.g. 49 for Germany)
- Area code (e.g. 89 for Munich)
- Local destination code (e.g. 7007)
The discriminating digit sequences for national and international calls
must also be provided:
- International prefix (e.g. 00)
- National prefix (e.g. 0)
The components of the the home ISDN number are required for DDI so that
the DDI number sent by the exchange can be reduced to the simple subscriber
number, which in turn is necessary for correct digit analysis in the
OpenScape 4000 system.
Example: Configuration of trunk circuits on the T2 primary rate access.
- Assign module DIU (2 PCM30 routes):
ADD-BCSU:MTYPE=DIU, LTG=gg, LTU=uu, SLOT=bbb, PARTNO=Q2096-X;
- Assign trunk group for 30 B-channels:
ADD-BUEND:TGRP=x, NAME="ISDN-S2AMT", NO=30;
- Assign S2 trunk circuit with 30 b channells in module
ADD-TDCSU:OPT=NEW, PEN=gg-uu-bbb-0/1, COTNO=number, COPNO=number, LCOSV=number, LCOSD=number, PROTVAR=ETSI, ISDNIP=00, ISDNNP=0, ISDNCC=49, ISDNAC=89, ISDNLC=722, NNO=number, DEV=S2COD, TGRP=x, BCGR=1;
Example: Configuration of trunk ciruits on the T0 basic access. - Assign module STMD (8 xS0 interfaces)
ADD-BCSU:MTYPE=DIU, LTG=gg, LTU=uu, SLOT=bbb, PARTNO=Q2174-X;
- Assign trunk group for 8 x S0-interfaces (2 B-channels ea.):
ADD-BUEND:TGRP=y, NAME="ISDN-S0AMT", NO=16;
- Assign 8 S0 trunk circuits in module
ADD-TDCSU:OPT=NEW, PEN=gg-uu-bbb-0, COTNO=number, COPNO=number, LCOSV=number, LCOSD=number, PROTVAR=ETSI, IISDNIP=00, ISDNNP=0, ISDNCC=49, ISDNAC=89, ISDNLC=722, NNO=number, DEV=S0COD, NO=8, TGRP=y;