Hello. I try to manage by dialog module every signaling session, that goes through my proxy.
I added newx mod params

modparam("dialog", "timeout_avp", "$avp(i:10)")
modparam("dialog", "dlg_flag", 4)
modparam("dialog", "initial_cbs_inscript", 1)
modparam("dialog", "profiles_with_value", "caller")
modparam("dialog", "track_cseq_updates", 1)
modparam("dialog", "ka_timer", 10)
modparam("dialog", "ka_interval", 30


And at request route I added this for all invite methods

if (is_method("INVITE")){
$dlg_ctx(timeout_route) = "DIALOG_END";
$avp(i:10)=43200;
$dlg_ctx(timeout_bye) = 1;
dlg_set_property("ka-src");
                dlg_set_property("ka-dst");
dlg_manage();
xlog("L_INFO","Dialog manage is {$ct}\n");
...
}

So after this As I think every session must be dialog managed session and every leg of call must be checked by keepalive OPTIONS packets but no one OPTIONS request generated  wen session goes through my proxy. 

thanks