diff --git a/src/libmsc/a_iface.c b/src/libmsc/a_iface.c
index 3a7690d94..26274d85b 100644
--- a/src/libmsc/a_iface.c
+++ b/src/libmsc/a_iface.c
@@ -141,6 +141,16 @@ static struct bsc_context *get_bsc_context_by_sccp_addr(const struct osmo_sccp_a
 	return NULL;
 }
 
+/* wrapper around osmo_sccp_tx_data_msg(): Transmit a fully encoded BSSAP (DTAP or BSSMAP) message */
+static int a_iface_tx_bssap(const struct ran_conn *conn, struct msgb *msg)
+{
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(conn->a.scu);
+
+	LOGPCONN(conn, LOGL_DEBUG, "N-DATA.req(%s)\n", msgb_hexdump_l2(msg));
+	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg);
+}
+
 /* Send DTAP message via A-interface, take ownership of msg */
 int a_iface_tx_dtap(struct msgb *msg)
 {
@@ -151,7 +161,6 @@ int a_iface_tx_dtap(struct msgb *msg)
 	OSMO_ASSERT(msg);
 	conn = (struct ran_conn *)msg->dst;
 	OSMO_ASSERT(conn);
-	OSMO_ASSERT(conn->a.scu);
 
 	LOGPCONN(conn, LOGL_DEBUG, "Passing DTAP message (DLCI=0x%02x) from MSC to BSC\n", link_id);
 
@@ -167,9 +176,8 @@ int a_iface_tx_dtap(struct msgb *msg)
 		return -EINVAL;
 	}
 
-	LOGPCONN(conn, LOGL_DEBUG, "N-DATA.req(%s)\n", msgb_hexdump_l2(msg_resp));
 	/* osmo_sccp_tx_data_msg() takes ownership of msg_resp */
-	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg_resp);
+	return a_iface_tx_bssap(conn, msg_resp);
 }
 
 /* Send Cipher mode command via A-interface */
@@ -186,9 +194,7 @@ int a_iface_tx_cipher_mode(const struct ran_conn *conn,
 	LOGPC(DBSSAP, LOGL_DEBUG, " key %s\n", osmo_hexdump_nospc(ei->key, ei->key_len));
 
 	msg_resp = gsm0808_create_cipher(ei, include_imeisv ? &crm : NULL);
-	LOGPCONN(conn, LOGL_DEBUG, "N-DATA.req(%s)\n", msgb_hexdump_l2(msg_resp));
-
-	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg_resp);
+	return a_iface_tx_bssap(conn, msg_resp);
 }
 
 /* Page a subscriber via A-interface */
@@ -407,9 +413,7 @@ int a_iface_tx_assignment(const struct gsm_trans *trans)
 	memcpy(&rtp_addr, &rtp_addr_in, sizeof(rtp_addr_in));
 
 	msg = gsm0808_create_ass(&ct, NULL, &rtp_addr, &scl, NULL);
-
-	LOGPCONN(conn, LOGL_DEBUG, "N-DATA.req(%s)\n", msgb_hexdump_l2(msg));
-	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg);
+	return a_iface_tx_bssap(conn, msg);
 }
 
 /* Send clear command via A-interface */
@@ -425,7 +429,7 @@ int a_iface_tx_clear_cmd(struct ran_conn *conn)
 		csfb_ind = true;
 
 	msg = gsm0808_create_clear_command2(GSM0808_CAUSE_CALL_CONTROL, csfb_ind);
-	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg);
+	return a_iface_tx_bssap(conn, msg);
 }
 
 int a_iface_tx_classmark_request(const struct ran_conn *conn)
@@ -435,7 +439,7 @@ int a_iface_tx_classmark_request(const struct ran_conn *conn)
 	LOGPCONN(conn, LOGL_INFO, "Tx BSSMAP CLASSMARK REQUEST to BSC\n");
 
 	msg = gsm0808_create_classmark_request();
-	return osmo_sccp_tx_data_msg(conn->a.scu, conn->a.conn_id, msg);
+	return a_iface_tx_bssap(conn, msg);
 }
 
 /* Callback function: Close all open connections */
diff --git a/tests/msc_vlr/msc_vlr_test_gsm_ciph.err b/tests/msc_vlr/msc_vlr_test_gsm_ciph.err
index af1138519..2fb9bd8c6 100644
--- a/tests/msc_vlr/msc_vlr_test_gsm_ciph.err
+++ b/tests/msc_vlr/msc_vlr_test_gsm_ciph.err
@@ -2452,6 +2452,7 @@ DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: vlr_loc
 DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: Set Ciphering Mode
 DMM IMSI-901700000004620: to determine whether A5/3 is supported, first ask for a Classmark Update to obtain Classmark 2
 DBSSAP RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: Tx BSSMAP CLASSMARK REQUEST to BSC
+DBSSAP RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: N-DATA.req([])
   BSC <--BSSAP-BSS-MANAGEMENT-- MSC: CLASSMARK REQ [L3]> 00 01 58 
 DMM RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: state_chg to RAN_CONN_S_WAIT_CLASSMARK_UPDATE
 DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: state_chg to VLR_ULA_S_WAIT_CIPH
@@ -2987,6 +2988,7 @@ DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: vlr_loc
 DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: Set Ciphering Mode
 DMM IMSI-901700000004620: to determine whether A5/3 is supported, first ask for a Classmark Update to obtain Classmark 2
 DBSSAP RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: Tx BSSMAP CLASSMARK REQUEST to BSC
+DBSSAP RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: N-DATA.req([])
   BSC <--BSSAP-BSS-MANAGEMENT-- MSC: CLASSMARK REQ [L3]> 00 01 58 
 DMM RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: state_chg to RAN_CONN_S_WAIT_CLASSMARK_UPDATE
 DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: state_chg to VLR_ULA_S_WAIT_CIPH
@@ -3295,6 +3297,7 @@ DVLR Process_Access_Request_VLR(IMSI-901700000004620:MSISDN-42342:GERAN-A-0:PAGI
 DVLR Process_Access_Request_VLR(IMSI-901700000004620:MSISDN-42342:GERAN-A-0:PAGING_RESP){PR_ARQ_S_WAIT_AUTH}: Set Ciphering Mode
 DMM IMSI-901700000004620:MSISDN-42342: to determine whether A5/3 is supported, first ask for a Classmark Update to obtain Classmark 2
 DBSSAP RAN_conn(IMSI-901700000004620:MSISDN-42342:GERAN-A-0:PAGING_RESP){RAN_CONN_S_AUTH_CIPH}: Tx BSSMAP CLASSMARK REQUEST to BSC
+DBSSAP RAN_conn(IMSI-901700000004620:MSISDN-42342:GERAN-A-0:PAGING_RESP){RAN_CONN_S_AUTH_CIPH}: N-DATA.req([])
   BSC <--BSSAP-BSS-MANAGEMENT-- MSC: CLASSMARK REQ [L3]> 00 01 58 
 DMM RAN_conn(IMSI-901700000004620:MSISDN-42342:GERAN-A-0:PAGING_RESP){RAN_CONN_S_AUTH_CIPH}: state_chg to RAN_CONN_S_WAIT_CLASSMARK_UPDATE
 DVLR Process_Access_Request_VLR(IMSI-901700000004620:MSISDN-42342:GERAN-A-0:PAGING_RESP){PR_ARQ_S_WAIT_AUTH}: state_chg to PR_ARQ_S_WAIT_CIPH
diff --git a/tests/msc_vlr/msc_vlr_test_ms_timeout.err b/tests/msc_vlr/msc_vlr_test_ms_timeout.err
index e09389c0c..72d116a08 100644
--- a/tests/msc_vlr/msc_vlr_test_ms_timeout.err
+++ b/tests/msc_vlr/msc_vlr_test_ms_timeout.err
@@ -686,6 +686,7 @@ DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: vlr_loc
 DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: Set Ciphering Mode
 DMM IMSI-901700000004620: to determine whether A5/3 is supported, first ask for a Classmark Update to obtain Classmark 2
 DBSSAP RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: Tx BSSMAP CLASSMARK REQUEST to BSC
+DBSSAP RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: N-DATA.req([])
   BSC <--BSSAP-BSS-MANAGEMENT-- MSC: CLASSMARK REQ [L3]> 00 01 58 
 DMM RAN_conn(IMSI-901700000004620:GERAN-A-0:LU){RAN_CONN_S_AUTH_CIPH}: state_chg to RAN_CONN_S_WAIT_CLASSMARK_UPDATE
 DVLR vlr_lu_fsm(IMSI-901700000004620:GERAN-A-0:LU){VLR_ULA_S_WAIT_AUTH}: state_chg to VLR_ULA_S_WAIT_CIPH
diff --git a/tests/msc_vlr/msc_vlr_tests.c b/tests/msc_vlr/msc_vlr_tests.c
index eb6df095d..4a1778983 100644
--- a/tests/msc_vlr/msc_vlr_tests.c
+++ b/tests/msc_vlr/msc_vlr_tests.c
@@ -193,6 +193,12 @@ void conn_conclude_cm_service_req(struct ran_conn *conn,
 
 enum osmo_rat_type rx_from_ran = OSMO_RAT_GERAN_A;
 
+/* SCCP user stub to make a_iface_tx_bssap() happy during test case execution */
+struct osmo_sccp_user {
+	uint8_t foo;
+};
+static struct osmo_sccp_user g_scu;
+
 struct ran_conn *conn_new(void)
 {
 	struct ran_conn *conn;
@@ -203,6 +209,8 @@ struct ran_conn *conn_new(void)
 			.conn_id = 42,
 		};
 		conn->iu.ue_ctx = ue_ctx;
+	} else {
+		conn->a.scu = &g_scu;
 	}
 	return conn;
 }