公共电话交换网
PSTN Public switched telephone network
public switched telephone network
PSTN
公共交换电话网
public switched telephone networks
PSTN
公共交换电话网路
PSTN
public switched telephone network
公用交换电话网
PSTN
PSTN:PublicSwitchTelephoneNetwork
public switching telephone network
public switched telephone network
公用交换电话网络
public switched telephone networks
PSTN
public switched telephone network
公众交换电话网络
public switched telephone network {= PSTN
public switch telephone network
数据电话交换数字服务
dataphone switched digital service
DSDS