diff --git a/TODO-RELEASE b/TODO-RELEASE
index d0852fc9b..f172501ae 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -7,3 +7,4 @@
 # If any interfaces have been added since the last public release: c:r:a + 1.
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what		description / commit summary line
+libosmogsm      >1.7.0          BTS_FEAT_OSMUX, RSL_IE_OSMO_OSMUX_CID
diff --git a/include/osmocom/bsc/bts.h b/include/osmocom/bsc/bts.h
index 752a00a73..b690652f3 100644
--- a/include/osmocom/bsc/bts.h
+++ b/include/osmocom/bsc/bts.h
@@ -590,6 +590,9 @@ struct gsm_bts {
 	struct amr_multirate_conf mr_full;
 	struct amr_multirate_conf mr_half;
 
+	/* osmux config: */
+	enum osmux_usage use_osmux;
+
 	/* PCU socket state */
 	char *pcu_sock_path;
 	struct pcu_sock_state *pcu_state;
diff --git a/include/osmocom/bsc/lchan.h b/include/osmocom/bsc/lchan.h
index a6048c26b..2de1227a7 100644
--- a/include/osmocom/bsc/lchan.h
+++ b/include/osmocom/bsc/lchan.h
@@ -299,6 +299,12 @@ struct gsm_lchan {
 			uint8_t rr_cause;
 			bool valid;
 		} ass_compl;
+
+		struct {
+			bool use;
+			uint8_t local_cid;
+			uint8_t remote_cid;
+		} osmux;
 	} abis_ip;
 
 	/* At first, the Timing Advance from the initial Channel Request. Later, the Timing Advance value received from
diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index 8ec94a91d..1c60405c4 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -2739,11 +2739,15 @@ static void ipac_parse_rtp(struct gsm_lchan *lchan, struct tlv_parsed *tv, const
 		port = ntohs(port);
 		lchan->abis_ip.connect_port = port;
 	}
+	if (TLVP_PRESENT(tv, RSL_IE_OSMO_OSMUX_CID)) {
+		lchan->abis_ip.osmux.remote_cid = tlvp_val8(tv, RSL_IE_OSMO_OSMUX_CID, 0);
+	}
 
 	LOG_LCHAN(lchan, LOGL_DEBUG, "Rx IPACC %s ACK:"
-		  " BTS=%s:%u conn_id=%u rtp_payload2=0x%02x speech_mode=0x%02x\n",
+		  " BTS=%s:%u conn_id=%u rtp_payload2=0x%02x speech_mode=0x%02x osmux_use=%d osmux_loc_cid=%d\n",
 		  label, ip_to_a(lchan->abis_ip.bound_ip), lchan->abis_ip.bound_port,
-		  lchan->abis_ip.conn_id, lchan->abis_ip.rtp_payload2, lchan->abis_ip.speech_mode);
+		  lchan->abis_ip.conn_id, lchan->abis_ip.rtp_payload2, lchan->abis_ip.speech_mode,
+		  lchan->abis_ip.osmux.use, lchan->abis_ip.osmux.local_cid);
 }
 
 /*! Send Issue IPA RSL CRCX to configure the RTP port of the BTS.
@@ -2768,9 +2772,13 @@ int rsl_tx_ipacc_crcx(const struct gsm_lchan *lchan)
 	/* 0x1- == receive-only, 0x-1 == EFR codec */
 	msgb_tv_put(msg, RSL_IE_IPAC_SPEECH_MODE, lchan->abis_ip.speech_mode);
 	msgb_tv_put(msg, RSL_IE_IPAC_RTP_PAYLOAD, lchan->abis_ip.rtp_payload);
+	if (lchan->abis_ip.osmux.use)
+		msgb_tlv_put(msg, RSL_IE_OSMO_OSMUX_CID, 1, &lchan->abis_ip.osmux.local_cid);
 
-	LOG_LCHAN(lchan, LOGL_DEBUG, "Sending IPACC CRCX to BTS: speech_mode=0x%02x RTP_PAYLOAD=%d\n",
-		  lchan->abis_ip.speech_mode, lchan->abis_ip.rtp_payload);
+	LOG_LCHAN(lchan, LOGL_DEBUG,
+		  "Sending IPACC CRCX to BTS: speech_mode=0x%02x RTP_PAYLOAD=%d osmux_use=%d osmux_loc_cid=%d\n",
+		  lchan->abis_ip.speech_mode, lchan->abis_ip.rtp_payload,
+		  lchan->abis_ip.osmux.use, lchan->abis_ip.osmux.local_cid);
 
 	msg->dst = rsl_chan_link(lchan);
 
@@ -2808,6 +2816,8 @@ struct msgb *rsl_make_ipacc_mdcx(const struct gsm_lchan *lchan, uint32_t dest_ip
 	msgb_tv_put(msg, RSL_IE_IPAC_RTP_PAYLOAD, lchan->abis_ip.rtp_payload);
 	if (lchan->abis_ip.rtp_payload2)
 		msgb_tv_put(msg, RSL_IE_IPAC_RTP_PAYLOAD2, lchan->abis_ip.rtp_payload2);
+	if (lchan->abis_ip.osmux.use)
+		msgb_tlv_put(msg, RSL_IE_OSMO_OSMUX_CID, 1, &lchan->abis_ip.osmux.local_cid);
 
 	msg->dst = rsl_chan_link(lchan);
 
@@ -2865,6 +2875,15 @@ static int abis_rsl_rx_ipacc_crcx_ack(struct msgb *msg)
 		return -EINVAL;
 	}
 
+	if (!lchan->abis_ip.osmux.use && TLVP_PRESENT(&tv, RSL_IE_OSMO_OSMUX_CID)) {
+		LOGP(DRSL, LOGL_NOTICE, "Received unexpected IE Osmux CID\n");
+		return -EINVAL;
+	}
+	if (lchan->abis_ip.osmux.use && !TLVP_PRESENT(&tv, RSL_IE_OSMO_OSMUX_CID)) {
+		LOGP(DRSL, LOGL_NOTICE, "Mandatory IE Osmux CID missing\n");
+		return -EINVAL;
+	}
+
 	ipac_parse_rtp(lchan, &tv, "CRCX");
 
 	osmo_fsm_inst_dispatch(lchan->fi_rtp, LCHAN_RTP_EV_IPACC_CRCX_ACK, 0);
diff --git a/src/osmo-bsc/bts.c b/src/osmo-bsc/bts.c
index 4976fe660..95e7430b1 100644
--- a/src/osmo-bsc/bts.c
+++ b/src/osmo-bsc/bts.c
@@ -428,6 +428,8 @@ struct gsm_bts *gsm_bts_alloc(struct gsm_network *net, struct gsm_bts_sm *bts_sm
 	memcpy(&bts->mr_half.bts_mode[0], &amr_hr_ms_bts_mode[0], sizeof(amr_hr_ms_bts_mode));
 	bts->mr_half.num_modes = ARRAY_SIZE(amr_hr_ms_bts_mode);
 
+	bts->use_osmux = OSMUX_USAGE_OFF;
+
 	bts_cbch_init(bts);
 	bts_etws_init(bts);
 
@@ -507,6 +509,13 @@ int gsm_bts_check_cfg(struct gsm_bts *bts)
 			     bts_gprs_mode_name(bts->gprs.mode));
 			return -EINVAL;
 		}
+		if (bts->use_osmux == OSMUX_USAGE_ONLY &&
+		    !osmo_bts_has_feature(&bts->features, BTS_FEAT_OSMUX)) {
+			LOGP(DNM, LOGL_ERROR,
+			     "(bts=%u) osmux use set to 'only', but BTS does not support Osmux\n",
+			     bts->nr);
+			return -EINVAL;
+		}
 	}
 
 	/* Verify the physical channel mapping */
diff --git a/src/osmo-bsc/bts_vty.c b/src/osmo-bsc/bts_vty.c
index 492cb9a5b..39007685f 100644
--- a/src/osmo-bsc/bts_vty.c
+++ b/src/osmo-bsc/bts_vty.c
@@ -2965,6 +2965,42 @@ DEFUN_USRATTR(cfg_bts_amr_hr_hyst3,
 	return check_amr_config(vty);
 }
 
+#define OSMUX_STR "RTP multiplexing\n"
+DEFUN_USRATTR(cfg_bts_osmux,
+	      cfg_bts_osmux_cmd,
+	      X(BSC_VTY_ATTR_NEW_LCHAN),
+	      "osmux (on|off|only)",
+	      OSMUX_STR "Enable OSMUX\n" "Disable OSMUX\n" "Only use OSMUX\n")
+{
+	struct gsm_bts *bts = vty->index;
+	enum osmux_usage use;
+
+	if (strcmp(argv[0], "off") == 0)
+		use = OSMUX_USAGE_OFF;
+	else if (strcmp(argv[0], "on") == 0)
+		use = OSMUX_USAGE_ON;
+	else if (strcmp(argv[0], "only") == 0)
+		use = OSMUX_USAGE_ONLY;
+	else
+		goto err;
+
+	if (!is_osmobts(bts))
+		goto err;
+
+	if (bts->features_known && use != OSMUX_USAGE_OFF &&
+	    !osmo_bts_has_feature(&bts->features, BTS_FEAT_OSMUX))
+		goto err;
+
+	bts->use_osmux = use;
+	return CMD_SUCCESS;
+
+err:
+	LOGP(DNM, LOGL_ERROR,
+	     "(bts=%u) Unable to set 'osmux %s', BTS does not support Osmux\n",
+	     bts->nr, argv[0]);
+	return CMD_WARNING;
+}
+
 #define TNUM_STR "T-number, optionally preceded by 't' or 'T'\n"
 DEFUN_ATTR(cfg_bts_t3113_dynamic, cfg_bts_t3113_dynamic_cmd,
 	   "timer-dynamic TNNNN",
@@ -4512,6 +4548,11 @@ static void config_write_bts_single(struct vty *vty, struct gsm_bts *bts)
 	config_write_bts_amr(vty, bts, &bts->mr_full, 1);
 	config_write_bts_amr(vty, bts, &bts->mr_half, 0);
 
+	if (bts->use_osmux != OSMUX_USAGE_OFF) {
+		vty_out(vty, " osmux %s%s", bts->use_osmux == OSMUX_USAGE_ON ? "on" : "only",
+			VTY_NEWLINE);
+	}
+
 	config_write_bts_gprs(vty, bts);
 
 	if (bts->excl_from_rf_lock)
@@ -4773,6 +4814,7 @@ int bts_vty_init(void)
 	install_element(BTS_NODE, &cfg_bts_amr_hr_hyst2_cmd);
 	install_element(BTS_NODE, &cfg_bts_amr_hr_hyst3_cmd);
 	install_element(BTS_NODE, &cfg_bts_amr_hr_start_mode_cmd);
+	install_element(BTS_NODE, &cfg_bts_osmux_cmd);
 	install_element(BTS_NODE, &cfg_bts_pcu_sock_cmd);
 	install_element(BTS_NODE, &cfg_bts_acc_rotate_cmd);
 	install_element(BTS_NODE, &cfg_bts_acc_rotate_quantum_cmd);
diff --git a/src/osmo-bsc/lchan_rtp_fsm.c b/src/osmo-bsc/lchan_rtp_fsm.c
index 504bb342e..87c235f36 100644
--- a/src/osmo-bsc/lchan_rtp_fsm.c
+++ b/src/osmo-bsc/lchan_rtp_fsm.c
@@ -138,9 +138,10 @@ static void lchan_rtp_fsm_wait_mgw_endpoint_available_onenter(struct osmo_fsm_in
 							      uint32_t prev_state)
 {
 	struct gsm_lchan *lchan = lchan_rtp_fi_lchan(fi);
+	struct gsm_bts *bts = lchan->ts->trx->bts;
 	struct osmo_mgcpc_ep *mgwep;
 	struct osmo_mgcpc_ep_ci *use_mgwep_ci = lchan_use_mgw_endpoint_ci_bts(lchan);
-	struct mgcp_conn_peer crcx_info = {};
+	struct mgcp_conn_peer crcx_info;
 
 	if (!is_ipaccess_bts(lchan->ts->trx->bts)) {
 		LOG_LCHAN_RTP(lchan, LOGL_DEBUG, "Audio link to-BTS via E1, skipping IPACC\n");
@@ -163,13 +164,20 @@ static void lchan_rtp_fsm_wait_mgw_endpoint_available_onenter(struct osmo_fsm_in
 
 	lchan->mgw_endpoint_ci_bts = osmo_mgcpc_ep_ci_add(mgwep, "to-BTS");
 
+	crcx_info = (struct mgcp_conn_peer){
+		.ptime = 20,
+		.x_osmo_osmux_use = bts->use_osmux != OSMUX_USAGE_OFF,
+		.x_osmo_osmux_cid = -1, /* -1 is wildcard */
+	};
 	if (lchan->conn) {
 		crcx_info.call_id = lchan->conn->sccp.conn_id;
 		if (lchan->conn->sccp.msc)
 			crcx_info.x_osmo_ign = lchan->conn->sccp.msc->x_osmo_ign;
 	}
-	crcx_info.ptime = 20;
 	mgcp_pick_codec(&crcx_info, lchan, true);
+	/* TODO: lchan_rtp_fail() here if crcx_info->codecs[] contains non-AMR and bts->use_osmux=ONLY.
+	  If bts->use_osmux=ON, only set .x_osmo_osmux_use if there's an AMR in crcx_info->codecs[].
+	  IF osmux=no, always set x_osmo_osmux_use=false*/
 
 	osmo_mgcpc_ep_ci_request(lchan->mgw_endpoint_ci_bts, MGCP_VERB_CRCX, &crcx_info,
 				fi, LCHAN_RTP_EV_MGW_ENDPOINT_AVAILABLE, LCHAN_RTP_EV_MGW_ENDPOINT_ERROR,
@@ -179,11 +187,26 @@ static void lchan_rtp_fsm_wait_mgw_endpoint_available_onenter(struct osmo_fsm_in
 static void lchan_rtp_fsm_wait_mgw_endpoint_available(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct gsm_lchan *lchan = lchan_rtp_fi_lchan(fi);
+	struct gsm_bts *bts = lchan->ts->trx->bts;
 	switch (event) {
 
 	case LCHAN_RTP_EV_MGW_ENDPOINT_AVAILABLE:
 		LOG_LCHAN_RTP(lchan, LOGL_DEBUG, "MGW endpoint: %s\n",
 			      osmo_mgcpc_ep_ci_name(lchan_use_mgw_endpoint_ci_bts(lchan)));
+		if (osmo_mgcpc_ep_ci_get_crcx_info_to_osmux_cid(lchan->mgw_endpoint_ci_bts,
+								&lchan->abis_ip.osmux.local_cid)) {
+			if (bts->use_osmux == OSMUX_USAGE_OFF) {
+				lchan_rtp_fail("Got Osmux CID from MGW but we didn't ask for it");
+				return;
+			}
+			lchan->abis_ip.osmux.use = true;
+		} else {
+			if (bts->use_osmux == OSMUX_USAGE_ONLY) {
+				lchan_rtp_fail("Got no Osmux CID from MGW but Osmux is mandatory");
+				return;
+			}
+			lchan->abis_ip.osmux.use = false;
+		}
 		lchan_rtp_fsm_state_chg(LCHAN_RTP_ST_WAIT_LCHAN_READY);
 		return;
 
@@ -415,6 +438,8 @@ static void connect_mgw_endpoint_to_lchan(struct osmo_fsm_inst *fi,
 	mdcx_info = (struct mgcp_conn_peer){
 		.port = to_lchan->abis_ip.bound_port,
 		.ptime = 20,
+		.x_osmo_osmux_use = lchan->abis_ip.osmux.use,
+		.x_osmo_osmux_cid = lchan->abis_ip.osmux.remote_cid,
 	};
 	mgcp_pick_codec(&mdcx_info, to_lchan, true);