diff --git a/openbsc/include/openbsc/abis_nm.h b/openbsc/include/openbsc/abis_nm.h
index 0fe9d8e..db2a659 100644
--- a/openbsc/include/openbsc/abis_nm.h
+++ b/openbsc/include/openbsc/abis_nm.h
@@ -28,6 +28,9 @@
 
 #include <openbsc/gsm_data.h>
 
+/* max number of attributes represented as 3GPP TS 52.021 §9.4.62 SW Description array */
+#define MAX_BTS_ATTR 5
+
 struct cell_global_id {
 	uint16_t mcc;
 	uint16_t mnc;
@@ -85,7 +88,7 @@
 			   uint8_t e1_subslot);
 int abis_nm_get_attr(struct gsm_bts *bts, uint8_t obj_class,
 		     uint8_t bts_nr, uint8_t trx_nr, uint8_t ts_nr,
-		     uint8_t *attr, uint8_t attr_len);
+		     const uint8_t *attr, uint8_t attr_len);
 int abis_nm_set_bts_attr(struct gsm_bts *bts, uint8_t *attr, int attr_len);
 int abis_nm_set_radio_attr(struct gsm_bts_trx *trx, uint8_t *attr, int attr_len);
 int abis_nm_set_channel_attr(struct gsm_bts_trx_ts *ts, uint8_t chan_comb);
diff --git a/openbsc/include/openbsc/gsm_data_shared.h b/openbsc/include/openbsc/gsm_data_shared.h
index 5c96a62..edc550e 100644
--- a/openbsc/include/openbsc/gsm_data_shared.h
+++ b/openbsc/include/openbsc/gsm_data_shared.h
@@ -545,6 +545,9 @@
 	BTS_FEAT_ECSD,
 	BTS_FEAT_HOPPING,
 	BTS_FEAT_MULTI_TSC,
+	BTS_FEAT_OML_ALERTS,
+	BTS_FEAT_AGCH_PCH_PROP,
+	BTS_FEAT_CBCH,
 };
 
 /*
@@ -676,6 +679,7 @@
 	struct gsm_bts_model *model;
 	enum gsm_band band;
 	char version[MAX_VERSION_LENGTH];
+	char sub_model[MAX_VERSION_LENGTH];
 
 	/* Connected PCU version (if any) */
 	char pcu_version[MAX_VERSION_LENGTH];
diff --git a/openbsc/src/libbsc/abis_nm.c b/openbsc/src/libbsc/abis_nm.c
index db0dbd2..5212f6a 100644
--- a/openbsc/src/libbsc/abis_nm.c
+++ b/openbsc/src/libbsc/abis_nm.c
@@ -439,6 +439,7 @@
 	return res;
 }
 
+/* 3GPP TS 52.021 §6.2.5 */
 static int abis_nm_rx_sw_act_req(struct msgb *mb)
 {
 	struct abis_om_hdr *oh = msgb_l2(mb);
@@ -447,7 +448,7 @@
 	struct tlv_parsed tp;
 	const uint8_t *sw_config;
 	int ret, sw_config_len, len;
-	struct abis_nm_sw_desc sw_descr[5];
+	struct abis_nm_sw_desc sw_descr[MAX_BTS_ATTR];
 
 	abis_nm_debugp_foh(DNM, foh);
 
@@ -1441,10 +1442,9 @@
 }
 #endif
 
-/* Chapter 8.11.1 */
-int abis_nm_get_attr(struct gsm_bts *bts, uint8_t obj_class,
-			uint8_t bts_nr, uint8_t trx_nr, uint8_t ts_nr,
-			uint8_t *attr, uint8_t attr_len)
+/* 3GPP TS 52.021 § 8.11.1 */
+int abis_nm_get_attr(struct gsm_bts *bts, uint8_t obj_class, uint8_t bts_nr, uint8_t trx_nr, uint8_t ts_nr,
+		     const uint8_t *attr, uint8_t attr_len)
 {
 	struct abis_om_hdr *oh;
 	struct msgb *msg = nm_msgb_alloc();