21AT dialingATIn (product identification code, where n = 0, 1, 4)When n = 0, the MCA displays the contents of S-registers S52–S54. The default is“960” (Smartmodem V-series 9600 modem). Other possible values are: “122”(Smartmodem 1200) and “240” (Smartmodem 2400).When n = 1, the result is “206.”When n = 4, the result is “a037800c004420” and then “b100000000” (theseare the same values that Smartmodem V-series 9600 returns).AT&Cn (carrier detect control, where n = 0, 1)When n = 0, carrier detect lead is always asserted.When n = 1, the carrier detect remains off except when the call is terminated.AT&Dn (response to DTR, where n = 0–3)When n = 0, the MCA ignores the status of DTR.When n = 1, the MCA resumes the off-line command state when on-to-offtransition of DTR occurs.When n = 2, the MCA drops the call when on-to-off transition of DTR occurs.When n = 3, the MCA hangs up when on-to-off transition of DTR occurs andreturns its Hayes parameters to their default settings.AT&Rn (clear-to-send options, where n = 0, 1)When n = 0, the CTS lead remains off.When n = 1, CTS is always present.AT&Sn (data-set-ready options, where n = 0, 1)When n = 1, the DSR lead is off.When n = 0, DSR is always present.AT&F (factory configuration profile)This returns S0 through S49 registers and AT configurations to their defaultsettings.