Modem 常用AT指令集(2) C1 Return OK message.返回OK信息Dn Dial modifier.拨号En - Command Echo 命令回显 E0 Turn off command echo.关闭回显 E1 Turn on command echo.打开回显Fn - Select Line Modulation (RC144 Models Only) 选择线路调制 F0 Select auto-detect mode (equivalent to N1).(RC144)自动侦察模式(等同于N1) F1 Select V.21 or Bell 103. (RC144)选择V.21或BELL103