scope:

This first part of ETS 300 899 specifies the interworking between Signalling System No.7 ISDN User Part (ISUP) version 2 as specified in [19] to [36] and Digital Subscriber Signalling System No. one (DSS1) as specified in [1] to [18] and [37] to [39]. The interworking between subsequent versions of the ISUP signalling protocol (ISUP version 3, etc.) and the DSS1 protocol shall be in accordance with the requirements as contained in this ETS unless explicitly specified otherwise in subsequent versions of the ISUP signalling protocol. This also applies to new services specified in the DSS1 signalling protocol (e.g. the Selective Call Forwarding services) that make use of the existing procedures in the ISUP protocol