Symbol,Reference iso,"[ISO/IEC 11572 (Basic Call) (Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Circuit mode bearer services -- Inter-exchange signalling procedures and protocol.)][ISO/IEC 11582 (Generic Functional Protocol) (Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Generic functional protocol for the support of supplementary services -- Inter-exchange signalling procedures and protocol.)]"