only add x-headers for INVITE|MESSAGE|REFER

* also excludes in-dialog

kamailio/auth.cfg

@@ -22,6 +22,10 @@ route[AUTH_HEADERS]
 {
    remove_hf_re("^X-");
 
+   if (!is_method("INVITE|MESSAGE|REFER") || has_totag()) {
+        return;
+   }
+
    xavp_params_implode("hf", "$var(outx)");
    $var(out) = $(var(outx){re.subst,/^(.*);$$/\1/});
    $var(c) = $(var(out){param.count});