自动交换网

• The test methods for the technical specifications of inband pulsing single frequency line signalling system for automatic telephone switching network
  电话自动交换网带内单频脉冲线路信号技术指标测试方法
• 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