ITU-T Q.957-1993
(撤回)使用DSS 1数字标识补充业务的第3阶段描述:条款1:用户至用户信令(UUS)-NO.1数字用户信令系统
Stage 3 Description for Additional Information Information Transfer Supplementary Services Using DSS 1 Clause 1 - User-to-User Signalling (UUS) - Digital Subscriber Signalling System No. 1 - Stage 3 Description for Supp. Services Using DSS 1 (Study Group