Hardware and software flow control comments were bogus. Thanks Giulioo!
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ModemType: Class2.0 # use class 2.0 interface
ModemRate: 19200 # DCE-DTE communication rate
-ModemFlowControl: rtscts # XON/XOFF flow control assumed
+ModemFlowControl: rtscts # hardware flow control
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ModemNoFlowCmd: AT&H0&I0&R1 # setup modem for no flow control
ModemHardFlowCmd: AT&H1&I0&R2 # setup modem for hardware flow control
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ModemType: Class1 # use class 1 interface
ModemRate: 19200 # rate for DCE-DTE communication
-ModemFlowControl: xonxoff # hardware flow control
+ModemFlowControl: xonxoff # software flow control
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ModemSetupDTRCmd: ATS13=1&D2 # setup so DTR drop resets modem
ModemSetupDCDCmd: AT&C1 # setup so DCD reflects carrier (or not)