ETSI PRTBR 21-1995 终端设备(TE).将TE连接到模拟公共交换电话网(PSTNs)的泛欧批准的附加要求(不包括支持语音电话业务的TE),其中网络寻址(若有)是通过双音多频信令来实现的
Terminal Equipment (TE); Attachment Requirements for Pan-European Approval for Connection to the Analogue Public Switched Telephone Networks (PSTNs) of TE (Excluding TE Supporting the Voice Telephony Service) in Which Network Addressing, if Provided, is