NF Z82-267-4*NF EN 300267-4:2001 综合业务数字网(ISDN)电话服务"7 kHz电话服务"、"电视电话"、"音频图形的会议服务"和"视频会议服务" 数字用户信令系统1号协议(DSS1)第4部分:抽象测试套和试验用部分协议履行附加信息
Integrated Services Digital Network (ISDN) - Telephony 7 kHz, videotelephony, audiographic conference and videoconference teleservices - Digital Subscriber Signalling System No one (DSS1) protocol - Part 4 : Abstract Test Suite (ATS) and partial Protocol