AstBill, Radius Billing or Other Installation

Asterisk Billing Installation I do not wish to use A2Billing for this as I am already using it for something else. I have trixbox 2.6.1.13 Billing software should do the following: When callers dial in, they are prompted to enter PIN. Software announces how much money they have in PIN Callers are then taken to a context that I determine and are billed per minute for being in that context. PINs can be auto generated by software or created by me manually then entered into software. I should be able to add or subtract credits/minutes/money with ease. I should be able to add or change the context that the callers are taken to. I will NOT send money via paypal before work is completed on my server. I can use GAF escrow before project is started or paypal AFTER project completion.