diff --git a/openbsc/src/libabis/Makefile.am b/openbsc/src/libabis/Makefile.am
index 7f5ac47..0df7b5a 100644
--- a/openbsc/src/libabis/Makefile.am
+++ b/openbsc/src/libabis/Makefile.am
@@ -7,6 +7,7 @@
 libabis_a_SOURCES = e1_input.c e1_input_vty.c \
 			input/misdn.c		\
 			input/ipaccess.c	\
+			input/hsl.c		\
 			input/dahdi.c		\
 			input/lapd.c
 
diff --git a/openbsc/src/libabis/input/hsl.c b/openbsc/src/libabis/input/hsl.c
new file mode 100644
index 0000000..12e974b
--- /dev/null
+++ b/openbsc/src/libabis/input/hsl.c
@@ -0,0 +1,457 @@
+/* OpenBSC Abis input driver for HSL Femto */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2011 by On-Waves
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/* HSL uses a much more primitive/simplified version of the IPA multiplex.
+ *
+ * They have taken out the nice parts like the ID_GET / ID_RESP for resolving
+ * the UNIT ID, as well as the keepalive ping/pong messages.  Furthermore, the
+ * Stream Identifiers are fixed on the BTS side (RSL always 0, OML always 0xff)
+ * and both OML+RSL share a single TCP connection.
+ *
+ * Other oddities include the encapsulation of BSSGP messages in the L3_INFO IE
+ * of RSL
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <time.h>
+#include <sys/fcntl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <arpa/inet.h>
+
+#include <osmocore/select.h>
+#include <osmocore/tlv.h>
+#include <osmocore/msgb.h>
+#include <openbsc/debug.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/abis_nm.h>
+#include <openbsc/abis_rsl.h>
+#include <openbsc/subchan_demux.h>
+#include <openbsc/e1_input.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/socket.h>
+#include <openbsc/signal.h>
+#include <osmocore/talloc.h>
+
+#define HSL_TCP_PORT	2500
+#define HSL_PROTO_DEBUG	0xdd
+
+#define PRIV_OML 1
+#define PRIV_RSL 2
+
+/* data structure for one E1 interface with A-bis */
+struct hsl_e1_handle {
+	struct bsc_fd listen_fd;
+	struct gsm_network *gsmnet;
+};
+
+static struct hsl_e1_handle *e1h;
+
+
+#define TS1_ALLOC_SIZE	900
+
+#define OML_UP		0x0001
+#define RSL_UP		0x0002
+
+int hsl_drop_oml(struct gsm_bts *bts)
+{
+	struct gsm_bts_trx *trx;
+	struct e1inp_ts *ts;
+	struct e1inp_line *line;
+	struct bsc_fd *bfd;
+
+	if (!bts || !bts->oml_link)
+		return -1;
+
+	/* send OML down */
+	ts = bts->oml_link->ts;
+	line = ts->line;
+	e1inp_event(ts, S_INP_TEI_DN, bts->oml_link->tei, bts->oml_link->sapi);
+
+	bfd = &ts->driver.ipaccess.fd;
+	bsc_unregister_fd(bfd);
+	close(bfd->fd);
+	bfd->fd = -1;
+
+	/* clean up OML and RSL */
+	e1inp_sign_link_destroy(bts->oml_link);
+	bts->oml_link = NULL;
+	e1inp_sign_link_destroy(bts->c0->rsl_link);
+	bts->c0->rsl_link = NULL;
+	bts->ip_access.flags = 0;
+
+	/* kill the E1 line now... as we have no one left to use it */
+	talloc_free(line);
+
+	return -1;
+}
+
+static int hsl_drop_ts_fd(struct e1inp_ts *ts, struct bsc_fd *bfd)
+{
+	struct e1inp_sign_link *link, *link2;
+	int bts_nr = -1;
+
+	llist_for_each_entry_safe(link, link2, &ts->sign.sign_links, list) {
+		bts_nr = link->trx->bts->bts_nr;
+		e1inp_sign_link_destroy(link);
+	}
+
+	bsc_unregister_fd(bfd);
+	close(bfd->fd);
+	bfd->fd = -1;
+
+	talloc_free(ts->line);
+
+	return bts_nr;
+}
+
+struct gsm_bts *find_bts_by_serno(struct gsm_network *net, unsigned long serno)
+{
+	struct gsm_bts *bts;
+
+	llist_for_each_entry(bts, &net->bts_list, list) {
+		if (bts->type != GSM_BTS_TYPE_HSL_FEMTO)
+			continue;
+
+		if (serno == bts->hsl.serno)
+			return bts;
+	}
+
+	return NULL;
+}
+
+
+static int process_hsl_rsl(struct msgb *msg, struct e1inp_line *line)
+{
+	char serno_buf[16];
+	uint8_t serno_len;
+	unsigned long serno;
+	struct gsm_bts *bts;
+
+	switch (msg->l2h[1]) {
+	case 0x80:
+		/*, contains Serial Number + SW version */
+		if (msg->l2h[2] != 0xc0)
+			break;
+		serno_len = msg->l2h[3];
+		if (serno_len > sizeof(serno_buf)-1)
+			serno_len = sizeof(serno_buf)-1;
+		memcpy(serno_buf, msg->l2h+4, serno_len);
+		serno_buf[serno_len] = '\0';
+		serno = strtoul(serno_buf, NULL, 10);
+		bts = find_bts_by_serno(e1h->gsmnet, serno);
+		if (!bts) {
+			LOGP(DINP, LOGL_ERROR, "Unable to find BTS config for "
+				"serial number %lu(%s)\n", serno, serno_buf);
+			return -EIO;
+		}
+
+		DEBUGP(DINP, "Identified HSL BTS Serial Number %lu\n", serno);
+
+		/* we shouldn't hardcode it, but HSL femto also hardcodes it... */
+		bts->oml_tei = 255;
+		bts->c0->rsl_tei = 0;
+		bts->oml_link = e1inp_sign_link_create(&line->ts[PRIV_OML - 1],
+							E1INP_SIGN_OML, bts->c0,
+							bts->oml_tei, 0);
+		bts->c0->rsl_link = e1inp_sign_link_create(&line->ts[PRIV_OML - 1],
+							E1INP_SIGN_RSL, bts->c0,
+							bts->c0->rsl_tei, 0);
+		e1inp_event(&line->ts[PRIV_OML-1], S_INP_TEI_UP, 255, 0);
+		e1inp_event(&line->ts[PRIV_OML-1], S_INP_TEI_UP, 0, 0);
+		bts->ip_access.flags |= OML_UP;
+		bts->ip_access.flags |= (RSL_UP << 0);
+		msgb_free(msg);
+		return 1;	/* == we have taken over the msg */
+	case 0x82:
+		/* FIXME: do something with BSSGP, i.e. forward it over
+		 * NSIP to OsmoSGSN */
+		return 0;
+	}
+	return 0;
+}
+
+static int handle_ts1_read(struct bsc_fd *bfd)
+{
+	struct e1inp_line *line = bfd->data;
+	unsigned int ts_nr = bfd->priv_nr;
+	struct e1inp_ts *e1i_ts = &line->ts[ts_nr-1];
+	struct e1inp_sign_link *link;
+	struct msgb *msg;
+	struct ipaccess_head *hh;
+	int ret = 0, error;
+
+	msg = ipaccess_read_msg(bfd, &error);
+	if (!msg) {
+		if (error == 0) {
+			int ret = hsl_drop_ts_fd(e1i_ts, bfd);
+			if (ret >= 0)
+				LOGP(DINP, LOGL_NOTICE, "BTS %u disappeared, dead socket\n",
+					ret);
+			else
+				LOGP(DINP, LOGL_NOTICE, "unknown BTS disappeared, dead socket\n");
+		}
+		return error;
+	}
+
+	DEBUGP(DMI, "RX %u: %s\n", ts_nr, hexdump(msgb_l2(msg), msgb_l2len(msg)));
+
+	hh = (struct ipaccess_head *) msg->data;
+	if (hh->proto == HSL_PROTO_DEBUG) {
+		LOGP(DINP, LOGL_NOTICE, "HSL debug: %s\n", msg->data + sizeof(*hh));
+		msgb_free(msg);
+		return ret;
+	}
+
+	/* HSL proprietary RSL extension */
+	if (hh->proto == 0 && msg->l2h[0] == 0x80) {
+		ret = process_hsl_rsl(msg, line);
+		if (ret < 0) {
+			/* FIXME: close connection */
+			hsl_drop_ts_fd(e1i_ts, bfd);
+			return ret;
+		} else if (ret == 1)
+			return 0;
+		/* else: continue... */
+	}
+
+	/* HSL for whatever reason chose to use 0x81 instead of 0x80 for FOM */
+	if (hh->proto == 255 && msg->l2h[0] == (ABIS_OM_MDISC_FOM | 0x01))
+		msg->l2h[0] = ABIS_OM_MDISC_FOM;
+
+	link = e1inp_lookup_sign_link(e1i_ts, hh->proto, 0);
+	if (!link) {
+		LOGP(DINP, LOGL_ERROR, "no matching signalling link for "
+			"hh->proto=0x%02x\n", hh->proto);
+		msgb_free(msg);
+		return -EIO;
+	}
+	msg->trx = link->trx;
+
+	switch (link->type) {
+	case E1INP_SIGN_RSL:
+		if (!(msg->trx->bts->ip_access.flags & (RSL_UP << msg->trx->nr))) {
+			e1inp_event(e1i_ts, S_INP_TEI_UP, link->tei, link->sapi);
+			msg->trx->bts->ip_access.flags |= (RSL_UP << msg->trx->nr);
+		}
+		ret = abis_rsl_rcvmsg(msg);
+		break;
+	case E1INP_SIGN_OML:
+		if (!(msg->trx->bts->ip_access.flags & OML_UP)) {
+			e1inp_event(e1i_ts, S_INP_TEI_UP, link->tei, link->sapi);
+			msg->trx->bts->ip_access.flags |= OML_UP;
+		}
+		ret = abis_nm_rcvmsg(msg);
+		break;
+	default:
+		LOGP(DINP, LOGL_NOTICE, "Unknown HSL protocol class 0x%02x\n", hh->proto);
+		msgb_free(msg);
+		break;
+	}
+	return ret;
+}
+
+static int ts_want_write(struct e1inp_ts *e1i_ts)
+{
+	e1i_ts->driver.ipaccess.fd.when |= BSC_FD_WRITE;
+
+	return 0;
+}
+
+static void timeout_ts1_write(void *data)
+{
+	struct e1inp_ts *e1i_ts = (struct e1inp_ts *)data;
+
+	/* trigger write of ts1, due to tx delay timer */
+	ts_want_write(e1i_ts);
+}
+
+static int handle_ts1_write(struct bsc_fd *bfd)
+{
+	struct e1inp_line *line = bfd->data;
+	unsigned int ts_nr = bfd->priv_nr;
+	struct e1inp_ts *e1i_ts = &line->ts[ts_nr-1];
+	struct e1inp_sign_link *sign_link;
+	struct msgb *msg;
+	u_int8_t proto;
+	int ret;
+
+	bfd->when &= ~BSC_FD_WRITE;
+
+	/* get the next msg for this timeslot */
+	msg = e1inp_tx_ts(e1i_ts, &sign_link);
+	if (!msg) {
+		/* no message after tx delay timer */
+		return 0;
+	}
+
+	switch (sign_link->type) {
+	case E1INP_SIGN_OML:
+		proto = IPAC_PROTO_OML;
+		/* HSL uses 0x81 for FOM for some reason */
+		if (msg->data[0] == ABIS_OM_MDISC_FOM)
+			msg->data[0] = ABIS_OM_MDISC_FOM | 0x01;
+		break;
+	case E1INP_SIGN_RSL:
+		proto = IPAC_PROTO_RSL;
+		break;
+	default:
+		msgb_free(msg);
+		bfd->when |= BSC_FD_WRITE; /* come back for more msg */
+		return -EINVAL;
+	}
+
+	msg->l2h = msg->data;
+	ipaccess_prepend_header(msg, sign_link->tei);
+
+	DEBUGP(DMI, "TX %u: %s\n", ts_nr, hexdump(msg->l2h, msgb_l2len(msg)));
+
+	ret = send(bfd->fd, msg->data, msg->len, 0);
+	msgb_free(msg);
+
+	/* set tx delay timer for next event */
+	e1i_ts->sign.tx_timer.cb = timeout_ts1_write;
+	e1i_ts->sign.tx_timer.data = e1i_ts;
+
+	/* Reducing this might break the nanoBTS 900 init. */
+	bsc_schedule_timer(&e1i_ts->sign.tx_timer, 0, e1i_ts->sign.delay);
+
+	return ret;
+}
+
+/* callback from select.c in case one of the fd's can be read/written */
+static int hsl_fd_cb(struct bsc_fd *bfd, unsigned int what)
+{
+	struct e1inp_line *line = bfd->data;
+	unsigned int ts_nr = bfd->priv_nr;
+	unsigned int idx = ts_nr-1;
+	struct e1inp_ts *e1i_ts;
+	int rc = 0;
+
+	/* In case of early RSL we might not yet have a line */
+
+	if (line)
+		e1i_ts = &line->ts[idx];
+
+	if (!line || e1i_ts->type == E1INP_TS_TYPE_SIGN) {
+		if (what & BSC_FD_READ)
+			rc = handle_ts1_read(bfd);
+		if (what & BSC_FD_WRITE)
+			rc = handle_ts1_write(bfd);
+	} else
+		LOGP(DINP, LOGL_ERROR, "unknown E1 TS type %u\n", e1i_ts->type);
+
+	return rc;
+}
+
+struct e1inp_driver hsl_driver = {
+	.name = "HSL",
+	.want_write = ts_want_write,
+	.default_delay = 0,
+};
+
+/* callback of the OML listening filedescriptor */
+static int listen_fd_cb(struct bsc_fd *listen_bfd, unsigned int what)
+{
+	int ret;
+	int idx = 0;
+	int i;
+	struct e1inp_line *line;
+	struct e1inp_ts *e1i_ts;
+	struct bsc_fd *bfd;
+	struct sockaddr_in sa;
+	socklen_t sa_len = sizeof(sa);
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	ret = accept(listen_bfd->fd, (struct sockaddr *) &sa, &sa_len);
+	if (ret < 0) {
+		perror("accept");
+		return ret;
+	}
+	LOGP(DINP, LOGL_NOTICE, "accept()ed new HSL link from %s\n",
+		inet_ntoa(sa.sin_addr));
+
+	line = talloc_zero(tall_bsc_ctx, struct e1inp_line);
+	if (!line) {
+		close(ret);
+		return -ENOMEM;
+	}
+	line->driver = &hsl_driver;
+	//line->driver_data = e1h;
+	/* create virrtual E1 timeslots for signalling */
+	e1inp_ts_config(&line->ts[1-1], line, E1INP_TS_TYPE_SIGN);
+
+	/* initialize the fds */
+	for (i = 0; i < ARRAY_SIZE(line->ts); ++i)
+		line->ts[i].driver.ipaccess.fd.fd = -1;
+
+	e1i_ts = &line->ts[idx];
+
+	bfd = &e1i_ts->driver.ipaccess.fd;
+	bfd->fd = ret;
+	bfd->data = line;
+	bfd->priv_nr = PRIV_OML;
+	bfd->cb = hsl_fd_cb;
+	bfd->when = BSC_FD_READ;
+	ret = bsc_register_fd(bfd);
+	if (ret < 0) {
+		LOGP(DINP, LOGL_ERROR, "could not register FD\n");
+		close(bfd->fd);
+		talloc_free(line);
+		return ret;
+	}
+
+        return ret;
+	//return e1inp_line_register(line);
+}
+
+int hsl_setup(struct gsm_network *gsmnet)
+{
+	int ret;
+
+	/* register the driver with the core */
+	/* FIXME: do this in the plugin initializer function */
+	ret = e1inp_driver_register(&hsl_driver);
+	if (ret)
+		return ret;
+
+	e1h = talloc_zero(tall_bsc_ctx, struct hsl_e1_handle);
+	if (!e1h)
+		return -ENOMEM;
+
+	e1h->gsmnet = gsmnet;
+
+	/* Listen for connections */
+	ret = make_sock(&e1h->listen_fd, IPPROTO_TCP, 0, HSL_TCP_PORT,
+			listen_fd_cb);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
diff --git a/openbsc/src/libbsc/Makefile.am b/openbsc/src/libbsc/Makefile.am
index 91be7fa..de76929 100644
--- a/openbsc/src/libbsc/Makefile.am
+++ b/openbsc/src/libbsc/Makefile.am
@@ -8,7 +8,11 @@
 			abis_om2000.c abis_om2000_vty.c \
 			abis_rsl.c bsc_rll.c \
 			paging.c \
-			bts_ericsson_rbs2000.c bts_ipaccess_nanobts.c bts_siemens_bs11.c bts_unknown.c \
+			bts_ericsson_rbs2000.c \
+			bts_ipaccess_nanobts.c \
+			bts_siemens_bs11.c \
+			bts_hsl_femtocell.c \
+			bts_unknown.c \
 			chan_alloc.c \
 			gsm_subscriber_base.c \
 			handover_decision.c handover_logic.c meas_rep.c \
diff --git a/openbsc/src/libbsc/abis_nm.c b/openbsc/src/libbsc/abis_nm.c
index 45db8ba..0e7fc8d 100644
--- a/openbsc/src/libbsc/abis_nm.c
+++ b/openbsc/src/libbsc/abis_nm.c
@@ -1080,6 +1080,12 @@
 	case NM_MT_IPACC_RESTART_NACK:
 		dispatch_signal(SS_NM, S_NM_IPACC_RESTART_NACK, NULL);
 		break;
+	case NM_MT_SET_BTS_ATTR_ACK:
+		/* The HSL wants an OPSTART _after_ the SI has been set */
+		if (mb->trx->bts->type == GSM_BTS_TYPE_HSL_FEMTO) {
+			abis_nm_opstart(mb->trx->bts, NM_OC_BTS, 255, 255, 255);
+		}
+		break;
 	}
 
 	abis_nm_queue_send_next(mb->trx->bts);
diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index 07a7dc6..58e2a7c 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -636,11 +636,14 @@
 	rsl_lchan_set_state(lchan, LCHAN_S_NONE);
 }
 
+static int rsl_rx_rf_chan_rel_ack(struct gsm_lchan *lchan);
+
 /* Chapter 8.4.14 / 4.7: Tell BTS to release the radio channel */
 static int rsl_rf_chan_release(struct gsm_lchan *lchan, int error)
 {
 	struct abis_rsl_dchan_hdr *dh;
 	struct msgb *msg;
+	int rc;
 
 	if (lchan->state == LCHAN_S_REL_ERR) {
 		LOGP(DRSL, LOGL_NOTICE, "%s is in error state not sending release.\n",
@@ -671,8 +674,15 @@
 				   msg->trx->bts->network->T3111 + 2, 0);
 	}
 
+	rc =  abis_rsl_sendmsg(msg);
+
 	/* BTS will respond by RF CHAN REL ACK */
-	return abis_rsl_sendmsg(msg);
+
+	/* The HSL Femto seems to 'forget' sending a REL ACK for TS1...TS7 */
+	if (lchan->ts->trx->bts->type == GSM_BTS_TYPE_HSL_FEMTO && lchan->ts->nr != 0)
+		rc = rsl_rx_rf_chan_rel_ack(lchan);
+
+	return rc;
 }
 
 static int rsl_rx_rf_chan_rel_ack(struct gsm_lchan *lchan)
diff --git a/openbsc/src/libbsc/bsc_init.c b/openbsc/src/libbsc/bsc_init.c
index 752056c..0072bb6 100644
--- a/openbsc/src/libbsc/bsc_init.c
+++ b/openbsc/src/libbsc/bsc_init.c
@@ -92,13 +92,14 @@
 static int generate_and_rsl_si(struct gsm_bts_trx *trx, enum osmo_sysinfo_type i)
 {
 	struct gsm_bts *bts = trx->bts;
-	int rc;
+	int si_len, rc, j;
 
 	/* Only generate SI if this SI is not in "static" (user-defined) mode */
 	if (!(bts->si_mode_static & (1 << i))) {
 		rc = gsm_generate_si(bts, i);
 		if (rc < 0)
 			return rc;
+		si_len = rc;
 	}
 
 	DEBUGP(DRR, "SI%s: %s\n", gsm_sitype_name(i),
@@ -109,8 +110,25 @@
 	case SYSINFO_TYPE_5bis:
 	case SYSINFO_TYPE_5ter:
 	case SYSINFO_TYPE_6:
-		rc = rsl_sacch_filling(trx, gsm_sitype2rsl(i),
-				       GSM_BTS_SI(bts, i), rc);
+		if (trx->bts->type == GSM_BTS_TYPE_HSL_FEMTO) {
+			/* HSL has mistaken SACCH INFO MODIFY for SACCH FILLING,
+			 * so we need a special workaround here */
+			/* This assumes a combined BCCH and TCH on TS1...7 */
+			for (j = 0; j < 4; j++)
+				rsl_sacch_info_modify(&trx->ts[0].lchan[j],
+						      gsm_sitype2rsl(i),
+						      GSM_BTS_SI(bts, i), si_len);
+			for (j = 1; j < 8; j++) {
+				rsl_sacch_info_modify(&trx->ts[j].lchan[0],
+						      gsm_sitype2rsl(i),
+						      GSM_BTS_SI(bts, i), si_len);
+				rsl_sacch_info_modify(&trx->ts[j].lchan[1],
+						      gsm_sitype2rsl(i),
+						      GSM_BTS_SI(bts, i), si_len);
+			}
+		} else
+			rc = rsl_sacch_filling(trx, gsm_sitype2rsl(i),
+					       GSM_BTS_SI(bts, i), rc);
 		break;
 	default:
 		rc = rsl_bcch_info(trx, gsm_sitype2rsl(i),
@@ -423,9 +441,16 @@
 	register_signal_handler(SS_INPUT, inp_sig_cb, NULL);
 
 	llist_for_each_entry(bts, &bsc_gsmnet->bts_list, list) {
-		bootstrap_bts(bts);
-		if (!is_ipaccess_bts(bts))
+		rc = bootstrap_bts(bts);
+
+		switch (bts->type) {
+		case GSM_BTS_TYPE_NANOBTS:
+		case GSM_BTS_TYPE_HSL_FEMTO:
+			break;
+		default:
 			rc = e1_reconfig_bts(bts);
+			break;
+		}
 
 		if (rc < 0) {
 			fprintf(stderr, "Error in E1 input driver setup\n");
@@ -435,6 +460,7 @@
 
 	/* initialize nanoBTS support omce */
 	rc = ipaccess_setup(bsc_gsmnet);
+	rc = hsl_setup(bsc_gsmnet);
 
 	return 0;
 }
diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index ed45afd..57a0c20 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -253,6 +253,8 @@
 		vty_out(vty, "  Unit ID: %u/%u/0, OML Stream ID 0x%02x%s",
 			bts->ip_access.site_id, bts->ip_access.bts_id,
 			bts->oml_tei, VTY_NEWLINE);
+	else if (bts->type == GSM_BTS_TYPE_HSL_FEMTO)
+		vty_out(vty, "  Serial Number: %lu%s", bts->hsl.serno, VTY_NEWLINE);
 	vty_out(vty, "  NM State: ");
 	net_dump_nmstate(vty, &bts->nm_state);
 	vty_out(vty, "  Site Mgr NM State: ");
@@ -497,13 +499,19 @@
 				VTY_NEWLINE);
 		}
 	}
-	if (is_ipaccess_bts(bts)) {
+	switch (bts->type) {
+	case GSM_BTS_TYPE_NANOBTS:
 		vty_out(vty, "  ip.access unit_id %u %u%s",
 			bts->ip_access.site_id, bts->ip_access.bts_id, VTY_NEWLINE);
 		vty_out(vty, "  oml ip.access stream_id %u%s", bts->oml_tei, VTY_NEWLINE);
-	} else {
+		break;
+	case GSM_BTS_TYPE_HSL_FEMTO:
+		vty_out(vty, "  hsl serial-number %lu%s", bts->hsl.serno, VTY_NEWLINE);
+		break;
+	default:
 		config_write_e1_link(vty, &bts->oml_e1_link, "  oml ");
 		vty_out(vty, "  oml e1 tei %u%s", bts->oml_tei, VTY_NEWLINE);
+		break;
 	}
 
 	/* if we have a limit, write it */
@@ -1584,6 +1592,23 @@
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_bts_serno,
+      cfg_bts_serno_cmd,
+      "hsl serial-number STRING",
+      "Set the HSL Serial Number of this BTS\n")
+{
+	struct gsm_bts *bts = vty->index;
+
+	if (bts->type != GSM_BTS_TYPE_HSL_FEMTO) {
+		vty_out(vty, "%% BTS is not of HSL type%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	bts->hsl.serno = strtoul(argv[0], NULL, 10);
+
+	return CMD_SUCCESS;
+}
+
 #define OML_STR	"Organization & Maintenance Link\n"
 #define IPA_STR "ip.access Specific Options\n"
 
@@ -2696,6 +2721,7 @@
 	install_element(BTS_NODE, &cfg_bts_tsc_cmd);
 	install_element(BTS_NODE, &cfg_bts_bsic_cmd);
 	install_element(BTS_NODE, &cfg_bts_unit_id_cmd);
+	install_element(BTS_NODE, &cfg_bts_serno_cmd);
 	install_element(BTS_NODE, &cfg_bts_stream_id_cmd);
 	install_element(BTS_NODE, &cfg_bts_oml_e1_cmd);
 	install_element(BTS_NODE, &cfg_bts_oml_e1_tei_cmd);
diff --git a/openbsc/src/libbsc/bts_hsl_femtocell.c b/openbsc/src/libbsc/bts_hsl_femtocell.c
new file mode 100644
index 0000000..2813195
--- /dev/null
+++ b/openbsc/src/libbsc/bts_hsl_femtocell.c
@@ -0,0 +1,146 @@
+/* OpenBSC support code for HSL Femtocell */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2011 by OnWaves
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <sys/types.h>
+
+#include <arpa/inet.h>
+
+#include <osmocore/tlv.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/abis_nm.h>
+#include <openbsc/abis_rsl.h>
+#include <openbsc/signal.h>
+#include <openbsc/e1_input.h>
+
+static struct gsm_bts_model model_hslfemto = {
+	.type = GSM_BTS_TYPE_HSL_FEMTO,
+	.nm_att_tlvdef = {
+		.def = {
+			/* no HSL specific OML attributes that we know of */
+		},
+	},
+};
+
+
+static const uint8_t l1_msg[] = {
+	0x80, 0x8a,
+		0xC4, 0x0b,
+};
+
+static const uint8_t conn_trau_msg[] = {
+	0x80, 0x81,
+		0xC1, 16,
+			0x02, 0x00, 0x00, 0x00, 0xC0, 0xA8, 0xEA, 0x01,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+static const uint8_t conn_trau_msg2[] = {
+	0x80, 0x81,
+		0xC1, 16,
+			0x02, 0x00, 0xd4, 0x07, 0xC0, 0xA8, 0xEA, 0x01,
+			0x38, 0xA4, 0x45, 0x00, 0x04, 0x59, 0x40, 0x00
+};
+
+static uint8_t oml_arfcn_bsic[] = {
+	0x81, 0x80, 0x00, 10,
+		NM_MT_SET_BTS_ATTR, NM_OC_BTS, 0xff, 0xff, 0xff,
+			NM_ATT_BCCH_ARFCN, 0x03, 0x67,
+			NM_ATT_BSIC, 0x00
+};
+
+static inline struct msgb *hsl_alloc_msgb(void)
+{
+	return msgb_alloc_headroom(1024, 127, "HSL");
+}
+
+static int hslfemto_bootstrap_om(struct gsm_bts *bts)
+{
+	struct msgb *msg;
+	uint8_t *cur;
+
+	msg = hsl_alloc_msgb();
+	cur = msgb_put(msg, sizeof(l1_msg));
+	memcpy(msg->data, l1_msg, sizeof(l1_msg));
+	msg->trx = bts->c0;
+	abis_rsl_sendmsg(msg);
+
+#if 1
+	msg = hsl_alloc_msgb();
+	cur = msgb_put(msg, sizeof(conn_trau_msg));
+	memcpy(msg->data, conn_trau_msg, sizeof(conn_trau_msg));
+	msg->trx = bts->c0;
+	abis_rsl_sendmsg(msg);
+#endif
+	msg = hsl_alloc_msgb();
+	cur = msgb_put(msg, sizeof(conn_trau_msg2));
+	memcpy(msg->data, conn_trau_msg2, sizeof(conn_trau_msg2));
+	msg->trx = bts->c0;
+	abis_rsl_sendmsg(msg);
+
+	*((uint16_t *)oml_arfcn_bsic+10) = htons(bts->c0->arfcn);
+	oml_arfcn_bsic[13] = bts->bsic;
+
+	msg = hsl_alloc_msgb();
+	cur = msgb_put(msg, sizeof(oml_arfcn_bsic));
+	memcpy(msg->data, oml_arfcn_bsic, sizeof(oml_arfcn_bsic));
+	msg->trx = bts->c0;
+	_abis_nm_sendmsg(msg, 0);
+
+	/* Delay the OPSTART until after SI have been set via RSL */
+	//abis_nm_opstart(bts, NM_OC_BTS, 255, 255, 255);
+
+	return 0;
+}
+
+/* Callback function to be called every time we receive a signal from INPUT */
+static int inp_sig_cb(unsigned int subsys, unsigned int signal,
+		      void *handler_data, void *signal_data)
+{
+	struct input_signal_data *isd = signal_data;
+
+	if (subsys != SS_INPUT)
+		return 0;
+
+	switch (signal) {
+	case S_INP_TEI_UP:
+		switch (isd->link_type) {
+		case E1INP_SIGN_OML:
+			hslfemto_bootstrap_om(isd->trx->bts);
+			break;
+		}
+	}
+
+	return 0;
+}
+
+int bts_model_hslfemto_init(void)
+{
+	model_hslfemto.features.data = &model_hslfemto._features_data[0];
+	model_hslfemto.features.data_len = sizeof(model_hslfemto._features_data);
+
+	gsm_btsmodel_set_feature(&model_hslfemto, BTS_FEAT_GPRS);
+	gsm_btsmodel_set_feature(&model_hslfemto, BTS_FEAT_EGPRS);
+
+	register_signal_handler(SS_INPUT, inp_sig_cb, NULL);
+
+	return gsm_bts_model_register(&model_hslfemto);
+}
diff --git a/openbsc/src/libbsc/system_information.c b/openbsc/src/libbsc/system_information.c
index 8a99c56..dc71938 100644
--- a/openbsc/src/libbsc/system_information.c
+++ b/openbsc/src/libbsc/system_information.c
@@ -370,9 +370,14 @@
 	memset(output, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
 
 	/* ip.access nanoBTS needs l2_plen!! */
-	if (is_ipaccess_bts(bts)) {
+	switch (bts->type) {
+	case GSM_BTS_TYPE_NANOBTS:
+	case GSM_BTS_TYPE_HSL_FEMTO:
 		*output++ = (l2_plen << 2) | 1;
 		l2_plen++;
+		break;
+	default:
+		break;
 	}
 
 	si5 = (struct gsm48_system_information_type_5 *) output;
@@ -397,9 +402,14 @@
 	memset(output, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
 
 	/* ip.access nanoBTS needs l2_plen!! */
-	if (is_ipaccess_bts(bts)) {
+	switch (bts->type) {
+	case GSM_BTS_TYPE_NANOBTS:
+	case GSM_BTS_TYPE_HSL_FEMTO:
 		*output++ = (l2_plen << 2) | 1;
 		l2_plen++;
+		break;
+	default:
+		break;
 	}
 
 	si6 = (struct gsm48_system_information_type_6 *) output;
diff --git a/openbsc/src/libcommon/gsm_data.c b/openbsc/src/libcommon/gsm_data.c
index f181fd1..b2c52e4 100644
--- a/openbsc/src/libcommon/gsm_data.c
+++ b/openbsc/src/libcommon/gsm_data.c
@@ -416,6 +416,7 @@
 	{ GSM_BTS_TYPE_BS11,	"bs11" },
 	{ GSM_BTS_TYPE_NANOBTS,	"nanobts" },
 	{ GSM_BTS_TYPE_RBS2000,	"rbs2000" },
+	{ GSM_BTS_TYPE_HSL_FEMTO, "hsl_femto" },
 	{ 0,			NULL }
 };
 
@@ -571,6 +572,8 @@
 	bts->model = model;
 
 	switch (bts->type) {
+	case GSM_BTS_TYPE_HSL_FEMTO:
+		bts->c0->rsl_tei = 0;
 	case GSM_BTS_TYPE_NANOBTS:
 		/* Set the default OML Stream ID to 0xff */
 		bts->oml_tei = 0xff;
diff --git a/openbsc/src/osmo-nitb/bsc_hack.c b/openbsc/src/osmo-nitb/bsc_hack.c
index 8c6d30b..88814b6 100644
--- a/openbsc/src/osmo-nitb/bsc_hack.c
+++ b/openbsc/src/osmo-nitb/bsc_hack.c
@@ -211,6 +211,7 @@
 extern int bts_model_bs11_init(void);
 extern int bts_model_nanobts_init(void);
 extern int bts_model_rbs2k_init(void);
+extern int bts_model_hslfemto_init(void);
 void talloc_ctx_init(void);
 
 extern enum node_type bsc_vty_go_parent(struct vty *vty);
@@ -241,6 +242,7 @@
 	bts_model_bs11_init();
 	bts_model_nanobts_init();
 	bts_model_rbs2k_init();
+	bts_model_hslfemto_init();
 
 	e1inp_init();