ETSI EN 300 356-8-2001 综合业务数字网(ISDN).7号信令系统(SS7).国际接口的ISDN用户部分(ISUP)版本4.第8部分:用户到用户信令(UUS)补充业务(版本4.1.2).ITU-T建议Q.737,第1条(19
Integrated Services Digital Network (ISDN); Signalling System No.7 (SS7); ISDN User Part (ISUP) Version 4 for the International Interface; Part 8: User-to-User Signalling (UUS) Supplementary Service (Version 4.1.2; ITU-T Recommendation Q.737, Clause 1 (19