diff --git a/src/tests/hnb-test-layers.h b/src/tests/hnb-test-layers.h
index 7ab273a..ab51ca9 100644
--- a/src/tests/hnb-test-layers.h
+++ b/src/tests/hnb-test-layers.h
@@ -14,3 +14,4 @@
 /* RANAP calls main with actual payload*/
 void hnb_test_nas_rx_dtap(struct hnb_test *hnb, void *data, int len);
 void hnb_test_rx_secmode_cmd(struct hnb_test *hnb, long ip_alg);
+void hnb_test_rx_iu_release(struct hnb_test *hnb);
diff --git a/src/tests/hnb-test-ranap.c b/src/tests/hnb-test-ranap.c
index 4986e98..a3cae29 100644
--- a/src/tests/hnb-test-ranap.c
+++ b/src/tests/hnb-test-ranap.c
@@ -50,5 +50,9 @@
 
 		hnb_test_rx_secmode_cmd(hnb, *first_alg);
 		return;
+
+	case RANAP_ProcedureCode_id_Iu_Release:
+		hnb_test_rx_iu_release(hnb);
+		return;
 	}
 }
diff --git a/src/tests/hnb-test.c b/src/tests/hnb-test.c
index 603f63b..2e2baf7 100644
--- a/src/tests/hnb-test.c
+++ b/src/tests/hnb-test.c
@@ -357,6 +357,20 @@
 	return hnb_test_tx_dt(hnb, gen_nas_auth_resp(vec.sres));
 }
 
+void hnb_test_tx_iu_release_req(struct hnb_test *hnb)
+{
+	RANAP_Cause_t cause = {
+		.present = RANAP_Cause_PR_radioNetwork,
+		.choice.transmissionNetwork = RANAP_CauseRadioNetwork_release_due_to_UE_generated_signalling_connection_release,
+	};
+	hnb_test_tx_dt(hnb, ranap_new_msg_iu_rel_req(&cause));
+}
+
+void hnb_test_tx_iu_release_compl(struct hnb_test *hnb)
+{
+	hnb_test_tx_dt(hnb, ranap_new_msg_iu_rel_compl());
+}
+
 static int hnb_test_nas_rx_mm(struct hnb_test *hnb, struct gsm48_hdr *gh, int len)
 {
 	struct hnbtest_chan *chan;
@@ -390,6 +404,7 @@
 
 	case GSM48_MT_MM_INFO:
 		hnb_test_nas_rx_mm_info(gh, len);
+		hnb_test_tx_iu_release_req(hnb);
 		return 0;
 
 	case GSM48_MT_MM_AUTH_REQ:
@@ -439,6 +454,11 @@
 	hnb_test_tx_dt(hnb, ranap_new_msg_sec_mod_compl(ip_alg, 0));
 }
 
+void hnb_test_rx_iu_release(struct hnb_test *hnb)
+{
+	hnb_test_tx_iu_release_compl(hnb);
+}
+
 int hnb_test_hnbap_rx(struct hnb_test *hnb, struct msgb *msg)
 {
 	HNBAP_PDU_t _pdu, *pdu = &_pdu;