I would like to start back at the beginning. What is your call flow like and your PSTN connections? How many PSTN connections? You are using a 7206 and a 5300 and 2 RADIUS Servers??
I can help streamline this network for you easier and cheaper just need to the network better. As far as billing, is this prepaid calling card and/or wholesale trafficing? What is your projection of minutes per month?
Desiging your own AAA application off of Cisco API’s TCL’s etc., I have to be honest and say I hope you have a minimum of 6 months to a year of patience in developing this. Not an easy task.
Looking forward to your answers