DoOpenComPort opens the Tapi port if there is a FTapiDev regardless of the FUseTapi setting.
Code needs to change to
procedure TApdCustomModemPager.DoOpenPort;
begin
if not(Assigned (FPort)) then {!!.02}
Exit; {!!.02}
if not FPort.Open then {!!.02}
// if Assigned(FTapiDev) then begin {!!.02}
if Assigned(FTapiDev) and FUseTapi then begin
FTapiDev.ConfigAndOpen; {!!.02}
FPort.TapiMode := tmOn {!!.02}
end else {!!.02}
FPort.Open := True;
DelayTicks(STD_DELAY, True);
SetPortOpts; {!!.02}
DelayTicks(STD_DELAY*2, True);
end;