So I need to enable WITH_ACCDB so that it can alter the database table as it seems. I enabled this and restarted kamailio but it is not logging the misscall in the "acc" or "missed_calls" tables. In the config file there is something like this,
$avp(oexten) = $rU;
        if (!lookup("location")) {
                $var(rc) = $rc;
                route(TOVOICEMAIL);
                t_newtran();
                switch ($var(rc)) {
                        case -1:
                        case -3:
                                send_reply("404", "Not Found");
                                exit;
                        case -2:
                                send_reply("405", "Method Not Allowed");
                                exit;
                }
        }

        # when routing via usrloc, log the missed calls also
        if (is_method("INVITE")) {
                setflag(FLT_ACCMISSED);