ETSI EN 300 121-2003 综合业务数字网(ISDN).用于国际ISDN互连的ITU-T 7号信令系统(SS7)的ISDN用户部分(ISUP)的应用(ISUP版本1).修改件1:国际紧急参考方案(IEPS)业务版本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 (V1.