For each incoming networking trunk a local or netwide night service destination can be defined (TDCSU / TACSU parameter INIGHT), which is used for trunk night service instead of the group night service destination.

TNS is active if a TNS destination is configured for the trunk and the feature is enabled within the system (AMO ZAND:ALDATA,INIGHT=YES).The TNS is active independent of the active night option and the user cannot decide as to whether a call is routed to the GNS or TNS target. The decision is made on a per attendant group basis by a new parameter in VFGR :- INIGHTPR.

The most important trunk night service configurations are described in Section 160.4, "Generation (Examples)". The feature must be enabled / disabled generally with the system wide parameter INIGHT (ZAND:ATND). If disabled, group night service GNS is active for trunk calls. If enabled, the processing of trunk calls depends on the parameter INGHTACT (ZAND:ATND). This system wide parameter defines an AC group within the network (from the originating node point of view) on which the trunk night service destination instead of the group night service destination should be used. I.e., assuming there is a sequence of CAS-diversions how many diversions are allowed before switching to the TNS destination.