UNE-ETS 300141-6ED1

Integrated Services Digital Network (ISDN);Call Hold (HOLD) supplementary service;Digital Subscriber Signalling System No. one (DSS1) protocol;Part 6: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification for the network (Endorsed by Asociación Espanola de Normalización in March of 2022.)