I'm digging old archives again, reviewing several charging scenarios I implemented in the rating & biling project in a mobile operator in Mexico throughout 2008-2009 (that uses a product named BSCS iX from LHS), trying to recall / rediscover the usage parameters that matter for telco operators (one of my current company's target market).
From there, try to understand why those parameters -- and relevant charging rules -- matter to them. That's the high-level objective.
Once we have a better / more solid idea about parameters & the charging rules, we can go backward, to identifying places in our application where we can / should tap those parameters from. The objective is to make the application "charging friendly". By that I mean, the design facilitates the need to provide the usage parameters asked by the charging system (supposedly owned by the telco operator).
After that, go forward again (to the middle). At that point we will have to verify if the data we have tapped from our application really is useful / usable. A test bed will be required. In this case, the test bed would a charging system, similar to the one(s) used by the telco operators. I will be looking into OpenRate soon.
Coming out of that we will have more confidence that we have more / sufficient knowledge to be able to deal with requests from the client (telco operator) for anything related to their charging requirements.
I'll post again once I have managed to try out OpenRate.