Process CANCEL before in-dialog requests. This prevents issues with some devices sending buggy CANCEL with To-tag when cancelling an initial INVITE.

etc/kamailio.cfg

@@ -452,11 +452,6 @@ request_route {
 	# NAT detection
 	route(NATDETECT);
 
-	# handle requests within SIP dialogs
-	route(WITHINDLG);
-
-	### only initial requests (no To tag)
-
 	# CANCEL processing
 	if (is_method("CANCEL"))
 	{
@@ -465,6 +460,11 @@ request_route {
 		exit;
 	}
 
+	# handle requests within SIP dialogs
+	route(WITHINDLG);
+
+	### only initial requests (no To tag)
+
 	t_check_trans();
 
 	# authentication