OENORM EN 300121 V 1.2.1
Integrated Services Digital Network (ISDN) - Application of the ISDN User Part (ISUP) of ITU-T Signalling System No.7 (SS7) for international ISDN interconnections (ISUP version 1) - Amendment 1: International Emergency Preference Scheme (IEPS) service [ITU-T Recommendation Q.767 Amendment 1 (2002), modified]