2400 bits per second modem standardized for use on 4 wire leased telephone - type circuits 在四线租用电话型电路上使用的标准化2400比特秒调制解调器
3.
4800 bits per second modem with manual equalizer standardized for use on leased telephone - type circuits 在租用电话型电路上使用的带人工均衡器的标准化的4800比特秒调制解调器
4.
Procedures for simultaneous transmission of data and digitally encoded voice signals over the pstn or over 2 - wire leased point - to - point telephone type circuits 在pstn或二线点对点租用电话型电路上同时传送数据和数字化编码语音信号的规程
5.
1200 bits per second duplex modem standardized for use in the general switched telephone network and on point - to - point 2 - wire leased telephone circuits 在电话自动交换网和点对点二线租用电话型电路上使用的标准化的1200比特秒双工调制解调器
