DIN EN 300267-1:2001 综合业务数字网(ISDN)."7 kHz电话服务"、"可视电话服务"、"视听会议服务"和"电视会议服务".数字用户用1号信令系统协议(DSS1).第1部分:协议规范
Integrated Services Digital Network (ISDN); Telephony 7 kHz, videotelephony, audiographic conference and videoconference teleservices - Digital Subscriber Signalling System No. one (DSS 1) protocol - Part 1: Protocol specification (Endorsement of the Engl