diff --git a/include/osmocom/gsm/bsslap.h b/include/osmocom/gsm/bsslap.h
new file mode 100644
index 0000000..b2174b3
--- /dev/null
+++ b/include/osmocom/gsm/bsslap.h
@@ -0,0 +1,57 @@
+/*! \addtogroup bsslap
+ *  @{
+ *  \file bsslap.h
+ * Message encoding and decoding for 3GPP TS 48.071 BSS LCS Assistance Protocol (BSSLAP).
+ */
+/*
+ * (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+#pragma once
+
+#include <osmocom/gsm/protocol/gsm_48_071.h>
+#include <osmocom/gsm/protocol/gsm_49_031.h>
+
+struct msgb;
+
+struct osmo_bsslap_err {
+	int rc;
+	enum bsslap_msgt msg_type;
+	enum bsslap_iei iei;
+	enum lcs_cause cause;
+	char *logmsg;
+};
+
+extern const struct value_string osmo_bsslap_msgt_names[];
+static inline const char *osmo_bsslap_msgt_name(enum bsslap_msgt val)
+{ return get_value_string(osmo_bsslap_msgt_names, val); }
+
+extern const struct value_string osmo_bsslap_iei_names[];
+static inline const char *osmo_bsslap_iei_name(enum bsslap_iei val)
+{ return get_value_string(osmo_bsslap_iei_names, val); }
+
+int osmo_bsslap_enc(struct msgb *msg, const struct bsslap_pdu *pdu);
+int osmo_bsslap_dec(struct bsslap_pdu *pdu,
+		    struct osmo_bsslap_err **err, void *err_ctx,
+		    const uint8_t *data, size_t len);
+
+/*! @} */
diff --git a/include/osmocom/gsm/protocol/gsm_48_071.h b/include/osmocom/gsm/protocol/gsm_48_071.h
new file mode 100644
index 0000000..fb9653a
--- /dev/null
+++ b/include/osmocom/gsm/protocol/gsm_48_071.h
@@ -0,0 +1,122 @@
+/*! \defgroup bsslap 3GPP TS 48.071 BSS LCS Assistance Protocol (BSSLAP).
+ *  @{
+ *  \file gsm_48_071.h
+ */
+/*
+ * (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+#pragma once
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+
+enum bsslap_msgt {
+	BSSLAP_MSGT_TA_REQUEST = 0x1,
+	BSSLAP_MSGT_TA_RESPONSE = 0x2,
+	BSSLAP_MSGT_REJECT = 0xa,
+	BSSLAP_MSGT_RESET = 0xb,
+	BSSLAP_MSGT_ABORT = 0xc,
+	BSSLAP_MSGT_TA_LAYER3 = 0xd,
+	BSSLAP_MSGT_MS_POS_CMD = 0xf,
+	BSSLAP_MSGT_MS_POS_RESP = 0x10,
+	BSSLAP_MSGT_UTDOA_REQ = 0x11,
+	BSSLAP_MSGT_UTDOA_RESP = 0x12,
+};
+
+enum bsslap_cause {
+	BSSLAP_CAUSE_CONGESTION = 0x0,
+	BSSLAP_CAUSE_CHAN_MODE_NOT_SUPP = 0x1,
+	BSSLAP_CAUSE_POS_PROC_NOT_SUPP = 0x2,
+	BSSLAP_CAUSE_OTHER_RADIO_EVT_FAIL = 0x3,
+	BSSLAP_CAUSE_INTRA_BSS_HO = 0x4,
+	BSSLAP_CAUSE_SUPERV_TIMER_EXPIRED = 0x5,
+	BSSLAP_CAUSE_INTER_BSS_HO = 0x6,
+	BSSLAP_CAUSE_LOSS_SIG_CONN_MS = 0x7,
+	BSSLAP_CAUSE_INCORR_SERV_CELL_ID = 0x8,
+	BSSLAP_CAUSE_BSSAP_LE_SEGMENT_ERR = 0x9,
+	BSSLAP_CAUSE_CONCUR_POS_PROC_NOT_EN = 0xa,
+};
+
+enum bsslap_iei {
+	BSSLAP_IEI_TA = 0x1,
+	BSSLAP_IEI_CELL_ID = 0x9,
+	BSSLAP_IEI_CHAN_DESC = 0x10,
+	BSSLAP_IEI_MEAS_REP = 0x14,
+	BSSLAP_IEI_CAUSE = 0x18,
+	BSSLAP_IEI_RRLP_FLAG = 0x19,
+	BSSLAP_IEI_RRLP = 0x1b,
+	BSSLAP_IEI_CELL_ID_LIST = 0x1c,
+	BSSLAP_IEI_ENH_MEAS_REP = 0x1d,
+	BSSLAP_IEI_LAC = 0x1e,
+	BSSLAP_IEI_FREQ_LIST = 0x21,
+	BSSLAP_IEI_MS_POWER = 0x22,
+	BSSLAP_IEI_DELTA_TIMER = 0x23,
+	BSSLAP_IEI_SERVING_CELL_ID = 0x24,
+	BSSLAP_IEI_ENCR_KEY = 0x25,
+	BSSLAP_IEI_CIPH_MODE_SET = 0x26,
+	BSSLAP_IEI_CHAN_MODE = 0x27,
+	BSSLAP_IEI_MR_CONFIG = 0x28,
+	BSSLAP_IEI_POLLING_REPETITION = 0x29,
+	BSSLAP_IEI_PACKET_CHAN_DESC = 0x2a,
+	BSSLAP_IEI_TLLI = 0x2b,
+	BSSLAP_IEI_TFI = 0x2c,
+	BSSLAP_IEI_TBF_START_TIME = 0x2d,
+	BSSLAP_IEI_PWRUP_START_TIME = 0x2e,
+	BSSLAP_IEI_LONG_ENCR_KEY = 0x2f,
+	BSSLAP_IEI_CONCUR_POS_PROC_F = 0x30,
+};
+
+struct bsslap_ta_response {
+	uint16_t cell_id;
+	uint8_t ta;
+
+	bool more_items; /*!< always set this to false */
+};
+
+struct bsslap_ta_layer3 {
+	uint8_t ta;
+
+	bool more_items; /*!< always set this to false */
+};
+
+struct bsslap_reset {
+	uint16_t cell_id;
+	uint8_t ta;
+	struct gsm48_chan_desc chan_desc;
+	enum bsslap_cause cause;
+
+	bool more_items; /*!< always set this to false */
+};
+
+struct bsslap_pdu {
+	enum bsslap_msgt msg_type;
+	union {
+		/* ta_request: a TA Request message consists only of the message type. */
+		struct bsslap_ta_response ta_response;
+		enum bsslap_cause reject;
+		struct bsslap_reset reset;
+		enum bsslap_cause abort;
+		struct bsslap_ta_layer3 ta_layer3;
+	};
+};
+
+/*! @} */
diff --git a/include/osmocom/gsm/protocol/gsm_49_031.h b/include/osmocom/gsm/protocol/gsm_49_031.h
new file mode 100644
index 0000000..b44a07e
--- /dev/null
+++ b/include/osmocom/gsm/protocol/gsm_49_031.h
@@ -0,0 +1,61 @@
+/*! \defgroup bssmap_le 3GPP TS 49.031 BSSMAP-LE.
+ *  @{
+ *  \file gsm_49_031.h
+ */
+/*
+ * (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/*! 3GPP TS 49.031 10.13 LCS Cause, also in 3GPP TS 48.008 3.2.2.66, which simply refers to the former. */
+enum lcs_cause {
+	LCS_CAUSE_UNSPECIFIED = 0,
+	LCS_CAUSE_SYSTEM_FAILURE = 1,
+	LCS_CAUSE_PROTOCOL_ERROR = 2,
+	LCS_CAUSE_DATA_MISSING_IN_REQ = 3,
+	LCS_CAUSE_UNEXP_DATA_IN_REQ = 4,
+	LCS_CAUSE_POS_METH_FAILURE = 5,
+	LCS_CAUSE_TGT_MS_UNREACHABLE = 6,
+	LCS_CAUSE_REQUEST_ABORTED = 7,
+	LCS_CAUSE_FACILITY_NOTSUPP = 8,
+	LCS_CAUSE_INTER_BSC_HO = 9,
+	LCS_CAUSE_INTRA_BSC_HO = 10,
+	LCS_CAUSE_CONGESTION = 11,
+	LCS_CAUSE_INTER_NSE_CHG = 12,
+	LCS_CAUSE_RA_UPDAT = 13,
+	LCS_CAUSE_PTMSI_REALLOC = 14,
+	LCS_CAUSE_GPRS_SUSPENSION = 15,
+};
+
+/*! 3GPP TS 49.031 10.13 LCS Cause, also in 3GPP TS 48.008 3.2.2.66, which simply refers to the former. */
+struct lcs_cause_ie {
+	bool present;
+	enum lcs_cause cause_val;
+	bool diag_val_present;
+	uint8_t diag_val;
+};
+
+/*! @} */