未来数据网络（FDN）功能体系架构
Function Architecture of Future Data Nerwork
2017-11-07
UNE-TBR 1-1999
TERMINAL EQUIPMENT (TE). ATTACHMENT REQUIREMENTS FOR TERMINAL EQUIPMENT TO BE CONNECTED TO CIRCUIT SWITCHED DATA NETWORKS AND LEASED CIRCUITS USING A CCITT RECOMMENDATION X.21 INTERFACE, OR AT AN INTERFACE PHYSICALLY, FUNCTIONALLY AND ELECTRICALLY COMPATIBLE WITH CCITT RECOMMENDATION X.21 BUT OPERAT
终端设备（TE） 使用CCITT建议X.21接口或在物理、功能和电气上与CCITT建议X.21兼容的接口处连接到电路交换数据网络和租用电路的终端设备的附件要求
1999-01-11
ETSI TBR 001
Terminal Equipment (TE); Attachment requirements for terminal equipment to be connected to circuit switched data networks and leased circuits using a CCITT Recommendation X.21 interface, or at an interface physically, functionally and electrically compatible with CCITT Recommendation X.21 but operat
终端设备（TE）；使用CCITT建议X.21接口或在物理、功能和电气上与CCITT建议X.21兼容的接口处连接到电路交换数据网络和租用电路的终端设备的附件要求