Функция набора номера модемом

var
  hCommFile : THandle;

procedure TForm1.Button1Click(Sender: TObject);
var
  PhoneNumber : string;
  CommPort : string;
  NumberWritten : LongInt;
begin
  PhoneNumber := 'ATDT 1-555-555-1212' + #13 + #10;
  CommPort := 'COM2';
  {Open the comm port}
  hCommFile := CreateFile(PChar(CommPort), GENERIC_WRITE, 0, nil,
                          OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if hCommFile=INVALID_HANDLE_VALUE then
  begin
    ShowMessage('Unable to open '+ CommPort);
    exit;
  end;
  NumberWritten:=0;
  if WriteFile(hCommFile, PChar(PhoneNumber)^, Length(PhoneNumber),
               NumberWritten, nil) = false then 
  begin
       ShowMessage('Unable to write to ' + CommPort);
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  {Close the port}
  CloseHandle(hCommFile);
end;