UNE-EN 301061-4V1.1.4

Integrated Services Digital Network (ISDN);Digital Subscriber Signalling System No. one (DSS1) protocol;Generic functional protocol for the support of supplementary services at the b" service entry point for Virtual Private Network (VPN) applications 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 August of 2021.)