Maybe a little late,
Thanks everyone, but I am really against to install an extra freeswitch instance for the billing. It makes very complex the call flow, troubleshoting and in most cases FAX wont work.
I did try the ASTPP before, horrible, hard to configure. I consider myself good on freeswitch, i know to code on perl, and a good sysadmin. But after watching how complex is to get this to work I abort.
So I decide to code my own billing and gladly, I can tell you that if you have all information needed (such as carrier rates and about 15 mins to get an explanation on how it works, you can have it working in less than an hour). I started to study FusionPBX code, and after some months I have a working nice FusionPBX LCR+Billing native application. It fully integrates in the Fusion, not out side, so you are able to bill for anything, incoming, internal (ext to ext, ext to conference, ext to ivr), or outgoing calls and it is able to get money by Paypal, Stripe (a good gw for CreditCards) and offline. Currently, I have just release version 1.0.2
If someone is interested, you can go to my website
www.okay.com.mx/en or contact me (gtalk prefered)
LD