Integrated Services Digital Network (ISDN) - Signalling system no. 7 - ISDN User Part (ISUP) version 1; Test specification; English version ETS 300335:1994
ISDN - Zeichengabesystem Nr. 7 - ISDN-Anwenderteil (ISUP) Version 1; Testspezifikation; Englische Fassung ETS 300335:1994