ISO IEC 21407:2001 pdf download – Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Specification, functional model and information flows — Simple dialog supplementary service. 1 Scope This International Standard specifies the supplementary service Simple Dialog (SS-SD), which is applicable to various basic services supported by Private Integrated Services Networks (PISNs). Basic services are specified in ISO/IEC 11574. Supplementary service SD enables a user to communicate with another user or application by the exchange of keypad and display information transparently over a PISN. Service specifications are produced in three stages, according to the...