ETR 016 : business telecommunications (BT): serveability performance objectives for private telecommunications networks (PTN) / European Telecommunications Standards Institute
ETR 023 : network aspects intelligent networks: framework / European Telecommunications Standards Institute
ETR 026 : network aspects: terminal selection principles for priority 1 and 2 services of MoU - ISDN applicable in multi-terminal environments at customer premises / European Telecommunications Standards Institute
ETR 027 : radio equipment and systems: methods of measurement for mobile radio equipment / European Telecommunications Standards Institute