scope:

This European Telecommunication Standard (ETS) specifies the stage three of circuit-mode on-demand basic telecommunication services for the pan-European integrated Services Digital Network (ISDN) as provided by European telecommunications operators at the T reference point or coincident S and T reference point (as defined in ITU_T Recommendation I.411[3]9 by means of the Digital Subscriber Signalling System No. one (DSS1). Stage three identifies the protocol procedures and switching functions needet to support a telecommunication service (see CCITT Recommendation I.130 [2]).