Hi,
We need to implement the following through Asterisk:
1) Three way calling.
2) Real time per minute billing for simultaneous calls.
We would really appreciate if you can show up some demo of the above features already implemented by you.
I can set you up easily as I have configured several billing servers. There is some widely available code on the internet which accomplishes what you need I would simple tailor it to your needs. I have several different servers on several different domains as well as a demo system which I could show to you immediately.