UNE-EN 301065-4V1.1.3

Integrated Services Digital Network (ISDN);Completion of Calls on No Reply (CCNR) supplementary service;Digital Subscriber Signalling System No. one (DSS1) protocol;Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification for the user (Endorsed by Asociación Espanola de Normalización in September of 2021.)