Access and Terminals (AT); Public Switched Telephone Network; Support of legacy terminals by Broadband IP networks and equipment; Part 1: General (common part covering both PSTN Analogue and ISDN TE)
接入和终端(AT);公共交换电话网;通过宽带IP网络和设备支持传统终端;第1部分:概述(通用部分包括PSTN模拟和ISDN TE)