[OpenSER-Users] Acc module question

Hi, I need to know when a channel of my media gateway is busy (included when the call is still ringing, etc). I have my Openser working with acc module storing in a mysql database. I don't use media proxy server. I can see the media gateway active calls in the acc table calculating the INVITEs whithout BYEs call registers. But I see Openser doesn't insert the INVITE register still and ACK arrives. It means I just can view in my database the number of active calls but i cannot know how many call attempts there's in the media gateway. How can I do to Openser insert the INVITE register to my database when an INVITE messages arrives and don't wait for the ACK message? Thanks in advance, Sergi