diff --git a/ns/NS_Tests.ttcn b/ns/NS_Tests.ttcn
index 8553684bc..105d3972c 100644
--- a/ns/NS_Tests.ttcn
+++ b/ns/NS_Tests.ttcn
@@ -162,6 +162,52 @@ testcase TC_tx_reset_rx_alive() runs on RAW_Test_CT {
 	f_sleep(1.0);
 }
 
+/* 48.016 7.2.1 transmit a UNIT DATA over a BLOCKED NSVC when ttcn3 blocked it
+ *
+ * TTCN  -> NS: reset
+ * TTCN <-  NS: reset ack
+ * TTCN  -> NS: unblock
+ * TTCN <-  NS: unblock ack
+ * TTCN  -> NS: block
+ * TTCN <-  NS: block ack
+ * TTCN  -> NS: unitdata
+ * TTCN <-  NS: status (cause blocked)
+ */
+testcase TC_tx_block_unitdata_over_blocked() runs on RAW_Test_CT {
+	f_tx_block();
+	f_sleep(1.0);
+
+	NSCP[0].send(ts_NS_UNITDATA(t_SduCtrlB, 42, '0011234242230101'O));
+	f_ns_exp(tr_NS_STATUS(NS_CAUSE_NSVC_BLOCKED));
+
+	setverdict(pass);
+	f_sleep(1.0);
+	f_clean_ns_codec();
+}
+
+/* 48.016 7.2.1 transmit a UNIT DATA over a BLOCKED NSVC when ns2 blocked it
+ *
+ * TTCN  -> NS: reset
+ * TTCN <-  NS: reset ack
+ * TTCN  -> NS: unblock
+ * TTCN <-  NS: unblock ack
+ * TTCN <-  NS: block
+ * TTCN  -> NS: block ack
+ * TTCN  -> NS: unitdata
+ * TTCN <-  NS: status (cause blocked)
+ */
+testcase TC_rx_block_unitdata_over_blocked() runs on RAW_Test_CT {
+	tx_block_by_vty();
+	f_sleep(1.0);
+
+	NSCP[0].send(ts_NS_UNITDATA(t_SduCtrlB, 42, '0011234242230101'O));
+	f_ns_exp(tr_NS_STATUS(NS_CAUSE_NSVC_BLOCKED));
+
+	setverdict(pass);
+	f_sleep(1.0);
+	f_clean_ns_codec();
+}
+
 /* 48.016 7.2 unblock procedure
  *
  * TTCN  -> NS: reset
@@ -219,9 +265,9 @@ testcase TC_tx_unblock_retries() runs on RAW_Test_CT {
  * TTCN  -> NS: block
  * TTCN <-  NS: block ack
  */
-testcase TC_tx_block() runs on RAW_Test_CT {
+function f_tx_block(float guard_secs := 30.0) runs on RAW_Test_CT {
 	f_init_vty();
-	f_init_ns_codec(mp_nsconfig, guard_secs := 30.0);
+	f_init_ns_codec(mp_nsconfig, guard_secs := guard_secs);
 
 	/* do a NS Reset procedure */
 	f_outgoing_ns_reset();
@@ -235,6 +281,11 @@ testcase TC_tx_block() runs on RAW_Test_CT {
 	f_sleep(1.0);
 }
 
+testcase TC_tx_block() runs on RAW_Test_CT {
+	f_tx_block()
+	f_clean_ns_codec();
+}
+
 /* 48.016 7.2 block procedure by vty
  *
  * TTCN  -> NS: reset
@@ -860,6 +911,8 @@ control {
 		execute( TC_tx_block() );
 		execute( TC_tx_block_by_vty() );
 		execute( TC_tx_block_by_vty_reset() );
+		execute( TC_tx_block_unitdata_over_blocked() );
+		execute( TC_rx_block_unitdata_over_blocked() );
 		// execute( TC_block_other_nsvc() ); // reset, unblock, sleep(1), block over another nsvci
 		/* 48.016 7.2 Unblock procedure */
 		execute( TC_tx_unblock() );