This European Telecommunication Standard (ETS) specifies the signalling protocol for the support of Call Diversion supplementary services (SS-DIV) at the Q reference point between Private Telecommunication Network eXchanges (PTNX) connected together within a Private Telecommunication Network (PTN). The Call Diversion supplementary services are Calling Forwarding Unconditional (SS-CFU), Call Forwarding Busy (SS-CFB), Call Forwarding No Reply (SS-CFNR) and Call Deflection (SS-CD).