[SR-Users] Evapi reply processing

Hey Guys, We are in the process of implementing prepaid control using CGRateS engine and for that we will be using evapi module (thanks Daniel again for that). I was wondering if you can advice us whether the path we are taking is the correct one. On INVITE, we will initiate a MaxCallTimeout (sort of call auth) to CGRateS via evapi. Once request sent, we should "park" the request somehow (right now we are considering sleep in the process via usleep and recheck for the answer every 5-10 milliseconds). Answer should be shared via htable. Could you recommend us a better approach? On reply, the answer processed in event route evapi:message-received should set in htable a key of combination callid:fromtag with the maximum call duration or auth reject if not enough balance. This key should be processed by the sleeping process on wakeup. What do u think, is there a better way to approach the 2 ways communication? Thanks in advance for any kind of tip! DanB