Well, that's almost enough information. Enough to guess with, anyway. You say you're using Windows, which means I can guess a desktop/laptop system, running an Intel device. Could be a mobile application, but let's suppose not, just for the hell of it.
RAS is a whole 'nother thang, and the serial port might play a part in establishing that remote access. You can find plenty on RAS at MSDN. As for the serial port, per se, you might want to start looking here