DC signalling是什么意思

中文翻译直流振铃

网络释义

1)DC signalling,直流振铃2)acldc ringing,交直流振铃3)direct current ringing,直流振铃<声>4)direct-current ringer,直流振铃器5)ac/dc ringing,交流/直流振铃6)DC ringing,直流振铃[电话]