Private Integrated Services Network (PISN); Specification, functional models and information flows; Call intrusion supplementary service [ISO/IEC 14845 (1996), modified] (V1.2.1e uitgave)
Private Integrated Services Network (PISN); Specification, functional models and information flows; Call intrusion supplementary service [ISO/IEC 14845 (1996), modified] (V1.2.1e édition)