diff --git a/etc/kamailio.cfg b/etc/kamailio.cfg
index da204e8224..5cde0a6ea2 100644
--- a/etc/kamailio.cfg
+++ b/etc/kamailio.cfg
@@ -168,6 +168,10 @@ import_file "kamailio-local.cfg"
 #!define FLB_NATB 6
 #!define FLB_NATSIPPING 7
 
+# - values
+#!trydef MSG_MAX_SIZE  16384
+#!trydef RURI_MAX_SIZE 512
+
 ####### Global Parameters #########
 
 /* LOG Levels: 3=DBG, 2=INFO, 1=NOTICE, 0=WARN, -1=ERR, ... */
@@ -670,6 +674,14 @@ route[REQINIT] {
 		# sl_send_reply("200", "OK");
 		exit;
 	}
+	if($msg(len) > MSG_MAX_SIZE) {
+		sl_send_reply("403", "Message too large");
+		exit;
+	}
+	if($(ru{s.len}) > RURI_MAX_SIZE) {
+		sl_send_reply("403", "R-URI too large");
+		exit;
+	}
 
 	if (!mf_process_maxfwd_header("10")) {
 		sl_send_reply("483", "Too Many Hops");
@@ -1065,6 +1077,10 @@ reply_route {
 		xlog("Malformed SIP response from $si:$sp\n");
 		drop;
 	}
+	if($msg(len) > MSG_MAX_SIZE) {
+		drop;
+	}
+
 	return;
 }