Specifies the signalling protocol for the support of Call Diversion supplementary services (SS-DIV) at the Q reference point between Private Integrated Services Network Exchanges (PINXs) connected together within a Private Integrated Services Network (PISN). The Call Diversion supplementary services are Call Forwarding Unconditional (SS-CFU), Call Forwarding Busy (SS-CFB), Call Forwarding No Reply (SS-CFNR) and Call Deflection (SS-CD). SS-CFU, SS-CFB, SS-CFNR, and SS-CD are suplementary services which permit a served user to have the PISN send all or specific incoming calls addressed to the served user's PISN number to another number. Also specifies additional signalling protocol requirements for the support of interactions at the Q reference point between SS-DIV and other supplementary services and ANFs. Is applicable to PINXs which can be interconnected to form a PISN.