Modem 常用AT指令集(5) M2 Turn speaker on during handshaking and while receiving carrier. M3 Turn speaker off during dialing and receiving carrier and turn speaker on during answering. Nn - Automode Enable 自动模式选择 N0 Turn off automode detection.关闭自动侦察模式 N1 Turn on automode detection.打开自动侦察模式 On - Return to On-Line Data Mode 返回数传模式 O0 Go on-line.返回上线 O1 Go on-line and initiate a retrain sequence.返回上线并进行再教育 P - Set Pulse Dial Default 选择脉冲拨号模式 Qn - Quiet Results Codes Control Q0 Allow result codes to DTE.允许返回结果码