we made diagram describing "money flow"
http://voip-trade.net/neotel-usecase.vsd
was there such diagram already ? (actually, I seen only "call flow" things)
Also we suggest the following on money:
there are two ways to add payment - "add payment" and "batch update" things. the proper way to do things would be:
1) actually update balance on either operation (and store payment history only for "add payment")
2) do not store payment history for "batch update"
the reason for such things would be privilege separation of administrator and accountant (person responsible for account money)