diff --git a/include/grgsm/flow_control/common.h b/include/grgsm/flow_control/common.h
new file mode 100644
index 0000000..fa4725c
--- /dev/null
+++ b/include/grgsm/flow_control/common.h
@@ -0,0 +1,38 @@
+/* -*- c++ -*- */
+/*
+ * @file
+ * @author Vadim Yanitskiy <axilirator@gmail.com>
+ * @section LICENSE
+ *
+ * Gr-gsm is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * Gr-gsm is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gr-gsm; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef INCLUDED_GSM_FLOW_CONTROL_COMMON_H
+#define INCLUDED_GSM_FLOW_CONTROL_COMMON_H
+
+namespace gr {
+  namespace gsm {
+
+    enum filter_policy {
+      FILTER_POLICY_DEFAULT,
+      FILTER_POLICY_PASS_ALL,
+      FILTER_POLICY_DROP_ALL,
+    };
+
+  } /* namespace gsm */
+} /* namespace gr */
+
+#endif