[Serusers] Pre-paid and post-paid system

[wangji]

Hi all,
   I know that we can use freeradius for a RADIUS server and freeside as billing system. And I know that freeside supports pre-paid card service. But I have no idea about how to use SER+ freeradius+ freeside + B2BUA to create a pre-paid and post-paid system. 
   Is it available? Is there any other way to do that?


Wangji