Need some Web Guru advice

I am looking at doing some voice based stuff on a site, and I am not too sure where to start. I was hoping some Web Guru's out there might help or know of some info.

Basically I am looking at doing a web based voice chat meeting serviceto integrate into our site. There are lots of voice based services and products out there but I am looking for something to fit this situation....

We want to have a 'page' that users can come into and set up to host their own voice only meeting (using our site). To start it can be a one to many type setup but will be live and have the capability to have multiple meetings going on at the same time. They schedule it on the site and then people can join that session to listen in. It needs to be something that can integrate easily into a site and requires no outside application that needs to be run ( like netmeeting).

Web-Ex has a great setup I want to mimick, but not sure how to go about it. I want to stay away from 3rd party hosts because they charge an arm and a leg for the service.

If anyone knows of anything let me know or point me in a direction :)

Thanks in advance

-Goob