PPP Dial in server problems

Hi, I have a working PPP dial-in server, but have a couple of problems. - The maximum speed anyone can connected is 28Kbps. I can't find out how to increase this. My modem is 56.6Kbps, and I can dial-out at approximately 45Kbps - This server has to share a phone like with a 'real' telephone, is there anyway to get it to detect the type of call (voice or data), so that it will only answer data calls, not the voice ones. Cheers Phil