My SER distributes calls to a bunch of Asterisk servers. Here's my route:

route{
        setflag(1);

       if (!mf_process_maxfwd_header("10")) {
               log("LOG: Too many hops\n");
               sl_send_reply("483","Too Many Hops");
               return;
       };

        if (loose_route()) {
                t_relay();
                return;
        };

        if(uri==myself) {
                if(method=="REGISTER") {
                        save("location");
                        return;
                };
        };

        if(method=="INVITE") {
               record_route();

               if (uri=~"^sip:1[0-9]*{10}@192.168.1.10") {
                        ds_select_dst("2", "0");
                        forward(uri:host, uri:port);
                        return;
               };
        };
}

I am trying to log all calls including failed, busy, congestion, incomplete using acc. Strangely, in my acc table I only see records affiliated with BYE and not with INVITE. Thru, all I see are successful calls. Is there a way I can make acc log incomplete calls?