Yes, there are some VoIP provider who provide platform for people to register numbers, you can install their software directly and charge money into the account, the voice quality is better than skype. Or you can use IP Phone hardware, and register the platform I just mentioned, that's the best way. Contact me if you like it.
You can always use alternatives to Skype such as MSN, Google Talk, Yahoo messenger etc. Also, if you want to have application sharing, audio-video conferencing, you can even try using various hosted services such as WebEx, gomeetnow, gotomeeting etc.
This is a new video calling website that is an alternative. It's called reflap and it's web based so you don't need to download any software. Also the calls you make the user doesn't need to be a reflap user. Most importantly, you can create a call address and let anyone that knows your call address to call you.