ETSI EN 301 060-4 English Printed Edition English PDF Integrated Services Digital Network (ISDN); Digital Subscriber Signalling System No. one (DSS1) protocol; Basic call control; Enhancement at the b service entry point for Virtual Private Network (VPN) applications; Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Informati

standard published 08/01/1999 by European Telecommunications Standards Institute