The present document specifies the stage three of the supplementary service interactions for the pan-European
Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators at the
T reference point or coincident S and T reference point (as defined in ITU-T Recommendation I.411 [32]) by means of
the Digital Subscriber Signalling System No. one (DSS1) protocol. Stage three identifies the protocol procedures and
switching functions needed to support a telecommunication service (see ITU-T Recommendation I.130 [29]).
The present document specifies the interactions between the Advice Of Charge (AOC), Completion of Calls to Busy
Subscriber (CCBS), Completion of Calls on No Reply (CCNR), Call Deflection (CD), Call Forwarding Busy (CFB),
Call Forwarding No Reply (CFNR), Call Forwarding Unconditional (CFU), Calling Line Identification Presentation
(CLIP), Calling Line Identification Restriction (CLIR), COnnected Line identification Presentation (COLP), COnnected
Line identification Restriction (COLR), CONFerence call, add-on (CONF), Explicit Call Transfer (ECT), Closed User
Group (CUG), Call Waiting (CW), Direct Dialling In (DDI), FreePHone (FPH), call HOLD (HOLD), Line Hunting
(LH), Malicious Call IDentification (MCID), Multiple Subscriber Number (MSN), Message Waiting Indication (MWI),
Outgoing Call Barring (OCB), Remote Control (RC), Selective Call Forwarding (SCF), SUB-addressing (SUB),
Terminal Portability (TP), User-to-User Signalling (UUS) and Three-Party (3PTY) supplementary services.
In addition, the present document specifies the protocol requirements at the T reference point where the supplementary
services are provided to the user via a private ISDN.
The present document does not specify the additional protocol requirements where the supplementary services are
provided to the user via a telecommunications network that is not an ISDN.