diff --git a/lib/flow_control/burst_sdcch_subslot_filter_impl.h b/lib/flow_control/burst_sdcch_subslot_filter_impl.h
index 40a603e..9068140 100644
--- a/lib/flow_control/burst_sdcch_subslot_filter_impl.h
+++ b/lib/flow_control/burst_sdcch_subslot_filter_impl.h
@@ -37,6 +37,13 @@
       burst_sdcch_subslot_filter_impl(subslot_filter_mode mode, unsigned int subslot);
       ~burst_sdcch_subslot_filter_impl();
       void process_burst(pmt::pmt_t msg);
+
+      /* External API */
+      unsigned int get_ss(void);
+      unsigned int set_ss(unsigned int ss);
+
+      subslot_filter_mode get_mode(void);
+      subslot_filter_mode set_mode(subslot_filter_mode mode);
     };
 
   } // namespace gsm