diff --git a/src/Makefile.am b/src/Makefile.am
index 53b2903..ae5715c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -3,10 +3,11 @@
 
 sbin_PROGRAMS = bsc_hack bs11_config
 
-bsc_hack_SOURCES = bsc_hack.c misdn.c abis_rsl.c abis_nm.c gsm_04_08.c gsm_data.c \
+bsc_hack_SOURCES = bsc_hack.c abis_rsl.c abis_nm.c gsm_04_08.c gsm_data.c \
 		gsm_subscriber.c msgb.c select.c chan_alloc.c timer.c debug.c db.c \
 		gsm_04_11.c telnet_interface.c telnet_parser.l subchan_demux.c \
-		trau_frame.c paging.c
+		trau_frame.c trau_mux.c paging.c e1_config.c e1_input.c \
+		input/misdn.c
 bsc_hack_LDADD = -ldl -ldbi
 
 bs11_config_SOURCES = bs11_config.c abis_nm.c gsm_data.c msgb.c debug.c select.c timer.c rs232.c
diff --git a/src/bs11_config.c b/src/bs11_config.c
index 47f5578..e623ade 100644
--- a/src/bs11_config.c
+++ b/src/bs11_config.c
@@ -103,7 +103,7 @@
 	abis_nm_bs11_set_trx1_pw(bts, trx1_password);
 
 	sleep(1);
-
+#if 0
 	cur = tlv_put(cur, NM_ATT_BS11_PASSWORD, 10,
 		      (u_int8_t *)trx1_password);
 	memcpy(cur, obj_bbsig0_attr, sizeof(obj_bbsig0_attr));
@@ -114,7 +114,7 @@
 				   sizeof(obj_pa0_attr), obj_pa0_attr);
 
 	abis_nm_bs11_set_trx_power(&bts->trx[1], BS11_TRX_POWER_GSM_30mW);
-
+#endif
 
 	return 0;
 }
diff --git a/src/bsc_hack.c b/src/bsc_hack.c
index 7fa12e7..1ff1075 100644
--- a/src/bsc_hack.c
+++ b/src/bsc_hack.c
@@ -45,6 +45,7 @@
 #include <openbsc/misdn.h>
 #include <openbsc/telnet_interface.h>
 #include <openbsc/paging.h>
+#include <openbsc/e1_input.h>
 
 /* global pointer to the gsm network data structure */
 static struct gsm_network *gsmnet;
@@ -654,17 +655,26 @@
 	set_system_infos(trx);
 }
 
-static void mi_cb(int event, struct gsm_bts *bts)
+void input_event(int event, enum e1inp_sign_type type, struct gsm_bts_trx *trx)
 {
 	switch (event) {
-	case EVT_E1_OML_UP:
-		bootstrap_om(bts);
+	case EVT_E1_TEI_UP:
+		switch (type) {
+		case E1INP_SIGN_OML:
+			bootstrap_om(trx->bts);
+			break;
+		case E1INP_SIGN_RSL:
+			bootstrap_rsl(trx);
+			break;
+		default:
+			break;
+		}
 		break;
-	case EVT_E1_RSL_UP:
-		bootstrap_rsl(bts->c0);
+	case EVT_E1_TEI_DN:
+		fprintf(stderr, "Lost some E1 TEI link\n");
+		/* FIXME: deal with TEI or L1 link loss */
 		break;
 	default:
-		/* FIXME: deal with TEI or L1 link loss */
 		break;
 	}
 }
@@ -697,15 +707,14 @@
 	bts->paging.channel_allocated = bsc_hack_channel_allocated;
 
 	telnet_init(gsmnet, 4242);
-	if (mi_setup(bts, 0, mi_cb) < 0)
-		return -EIO;
 
-	return 0;
+	/* E1 mISDN input setup */
+	return e1_config(bts);
 }
 
-
 static void create_pcap_file(char *file)
 {
+#if 0
 	mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
 	int fd = open(file, O_WRONLY|O_TRUNC|O_CREAT, mode);
 
@@ -715,6 +724,9 @@
 	}
 
 	mi_set_pcap_fd(fd);
+#else
+	fprintf(stderr, "PCAP support currently disabled!!\n");
+#endif
 }
 
 static void print_usage()
@@ -815,6 +827,8 @@
 
 int main(int argc, char **argv)
 {
+	int rc;
+
 	/* parse options */
 	handle_options(argc, argv);
 
@@ -830,7 +844,9 @@
 	}
 	printf("DB: Database prepared.\n");
 
-	bootstrap_network();
+	rc = bootstrap_network();
+	if (rc < 0)
+		exit(1);
 
 	signal(SIGHUP, &signal_handler);
 	signal(SIGABRT, &signal_handler);
diff --git a/src/e1_config.c b/src/e1_config.c
new file mode 100644
index 0000000..cf3a94b
--- /dev/null
+++ b/src/e1_config.c
@@ -0,0 +1,57 @@
+#include <string.h>
+#include <errno.h>
+
+#include <openbsc/gsm_data.h>
+#include <openbsc/e1_input.h>
+
+#define SAPI_L2ML	0
+#define SAPI_OML	62
+#define SAPI_RSL	0	/* 63 ? */
+
+#define TEI_L2ML	127
+#define TEI_OML		25
+#define TEI_RSL		1
+
+/* do some compiled-in configuration for our BTS/E1 setup */
+int e1_config(struct gsm_bts *bts)
+{
+	struct e1inp_line *line;
+	struct e1inp_ts *sign_ts;
+	struct e1inp_sign_link *oml_link, *rsl_link;
+
+	line = malloc(sizeof(*line));
+	if (!line)
+		return -ENOMEM;
+	memset(line, 0, sizeof(*line));
+
+	/* create E1 timeslots for signalling and TRAU frames */
+	e1inp_ts_config(&line->ts[1-1], line, E1INP_TS_TYPE_SIGN);
+	e1inp_ts_config(&line->ts[2-1], line, E1INP_TS_TYPE_TRAU);
+	e1inp_ts_config(&line->ts[3-1], line, E1INP_TS_TYPE_TRAU);
+
+	/* create signalling links for TS1 */
+	sign_ts = &line->ts[1-1];
+	oml_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_OML,
+					  bts->c0, TEI_OML, SAPI_OML);
+	rsl_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_RSL,
+					  bts->c0, TEI_RSL, SAPI_RSL);
+
+	/* create back-links from bts/trx */
+	bts->oml_link = oml_link;
+	bts->c0->rsl_link = rsl_link;
+
+#if 0
+	/* create E1 timeslots for signalling and TRAU frames */
+	e1inp_ts_config(&line->ts[4-1], line, E1INP_TS_TYPE_TRAU);
+	e1inp_ts_config(&line->ts[5-1], line, E1INP_TS_TYPE_TRAU);
+
+	/* create signalling links for TS1 */
+	sign_ts = &line->ts[1-1];
+	rsl_link = e1inp_sign_link_create(sign_ts, E1INP_SIGN_RSL,
+					  &bts->trx[1], TEI_RSL+1, SAPI_RSL);
+	/* create back-links from trx */
+	bts->trx[1].rsl_link = rsl_link;
+#endif
+
+	return mi_setup(0, line, NULL);
+}
diff --git a/src/e1_input.c b/src/e1_input.c
new file mode 100644
index 0000000..8ae2d1c
--- /dev/null
+++ b/src/e1_input.c
@@ -0,0 +1,453 @@
+/* OpenBSC Abis interface to E1 */
+
+/* (C) 2008-2009 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * 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.
+ *
+ */
+
+#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 <mISDNif.h>
+
+//#define AF_COMPATIBILITY_FUNC
+//#include <compat_af_isdn.h>
+#define AF_ISDN 34
+#define PF_ISDN AF_ISDN
+
+#include <openbsc/select.h>
+#include <openbsc/msgb.h>
+#include <openbsc/debug.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/e1_input.h>
+#include <openbsc/abis_nm.h>
+#include <openbsc/abis_rsl.h>
+#include <openbsc/linuxlist.h>
+#include <openbsc/subchan_demux.h>
+#include <openbsc/trau_mux.h>
+
+#define NUM_E1_TS	32
+
+/* list of all E1 drivers */
+static LLIST_HEAD(driver_list);
+
+/* list of all E1 lines */
+static LLIST_HEAD(line_list);
+
+#if 0
+/*
+ * pcap writing of the misdn load
+ * pcap format is from http://wiki.wireshark.org/Development/LibpcapFileFormat
+ */
+#define DLT_LINUX_LAPD		177
+#define PCAP_INPUT		0
+#define PCAP_OUTPUT		1
+
+struct pcap_hdr {
+	u_int32_t magic_number;
+	u_int16_t version_major;
+	u_int16_t version_minor;
+	int32_t  thiszone;
+	u_int32_t sigfigs;
+	u_int32_t snaplen;
+	u_int32_t network;
+} __attribute__((packed));
+
+struct pcaprec_hdr {
+	u_int32_t ts_sec;
+	u_int32_t ts_usec;
+	u_int32_t incl_len;
+	u_int32_t orig_len;
+} __attribute__((packed));
+
+struct fake_linux_lapd_header {
+        u_int16_t pkttype;
+	u_int16_t hatype;
+	u_int16_t halen;
+	u_int64_t addr;
+	int16_t protocol;
+} __attribute__((packed));
+
+struct lapd_header {
+	u_int8_t ea1 : 1;
+	u_int8_t cr : 1;
+	u_int8_t sapi : 6;
+	u_int8_t ea2 : 1;
+	u_int8_t tei : 7;
+	u_int8_t control_foo; /* fake UM's ... */
+} __attribute__((packed));
+
+static_assert((int)&((struct fake_linux_lapd_header*)NULL)->hatype == 2,	hatype_offset);
+static_assert((int)&((struct fake_linux_lapd_header*)NULL)->halen == 4,		halen_offset);
+static_assert((int)&((struct fake_linux_lapd_header*)NULL)->addr == 6,		addr_offset);
+static_assert((int)&((struct fake_linux_lapd_header*)NULL)->protocol == 14,	proto_offset);
+static_assert(sizeof(struct fake_linux_lapd_header) == 16,			lapd_header_size);
+
+
+static int pcap_fd = -1;
+
+void mi_set_pcap_fd(int fd)
+{
+	int ret;
+	struct pcap_hdr header = {
+		.magic_number	= 0xa1b2c3d4,
+		.version_major	= 2,
+		.version_minor	= 4,
+		.thiszone	= 0,
+		.sigfigs	= 0,
+		.snaplen	= 65535,
+		.network	= DLT_LINUX_LAPD,
+	};
+
+	pcap_fd = fd;
+	ret = write(pcap_fd, &header, sizeof(header));
+}
+
+/* This currently only works for the D-Channel */
+static void write_pcap_packet(int direction, struct sockaddr_mISDN* addr,
+			      struct msgb *msg) {
+	if (pcap_fd < 0)
+		return;
+
+	int ret;
+	time_t cur_time;
+	struct tm *tm;
+
+	struct fake_linux_lapd_header header = {
+		.pkttype	= 4,
+		.hatype		= 0,
+		.halen		= 0,
+		.addr		= direction == PCAP_OUTPUT ? 0x0 : 0x1,
+		.protocol	= ntohs(48),
+	};
+
+	struct lapd_header lapd_header = {
+		.ea1		= 0,
+		.cr		= direction == PCAP_OUTPUT ? 1 : 0,
+		.sapi		= addr->sapi & 0x3F,
+		.ea2		= 1,
+		.tei		= addr->tei & 0x7F,
+		.control_foo	= 0x03 /* UI */,
+	};	
+
+	struct pcaprec_hdr payload_header = {
+		.ts_sec	    = 0,
+		.ts_usec    = 0,
+		.incl_len   = msg->len + sizeof(struct fake_linux_lapd_header)
+				+ sizeof(struct lapd_header)
+				- MISDN_HEADER_LEN,
+		.orig_len   = msg->len + sizeof(struct fake_linux_lapd_header)
+				+ sizeof(struct lapd_header)
+				- MISDN_HEADER_LEN,
+	};
+
+
+	cur_time = time(NULL);
+	tm = localtime(&cur_time);
+	payload_header.ts_sec = mktime(tm);
+
+	ret = write(pcap_fd, &payload_header, sizeof(payload_header));
+	ret = write(pcap_fd, &header, sizeof(header));
+	ret = write(pcap_fd, &lapd_header, sizeof(lapd_header));
+	ret = write(pcap_fd, msg->data + MISDN_HEADER_LEN,
+			msg->len - MISDN_HEADER_LEN);
+}
+#endif
+
+/* callback when a TRAU frame was received */
+static int subch_cb(struct subch_demux *dmx, int ch, u_int8_t *data, int len,
+		    void *_priv)
+{
+	struct e1inp_ts *e1i_ts = _priv;
+	struct gsm_e1_subslot src_ss;
+
+	src_ss.e1_nr = e1i_ts->line->num;
+	src_ss.e1_ts = e1i_ts->num;
+	src_ss.e1_ts_ss = ch;
+
+	return trau_mux_input(&src_ss, data, len);
+}
+
+int abis_rsl_sendmsg(struct msgb *msg)
+{
+	struct e1inp_sign_link *sign_link;
+	struct e1inp_driver *e1inp_driver;
+
+	msg->l2h = msg->data;
+
+	if (!msg->trx || !msg->trx->rsl_link) {
+		fprintf(stderr, "rsl_sendmsg: msg->trx == NULL\n");
+		return -EINVAL;
+	}
+
+	sign_link = msg->trx->rsl_link;
+	msgb_enqueue(&sign_link->tx_list, msg);
+
+	/* notify the driver we have something to write */
+	e1inp_driver = sign_link->ts->line->driver;
+	e1inp_driver->want_write(sign_link->ts);
+
+	return 0;
+}
+
+int _abis_nm_sendmsg(struct msgb *msg)
+{
+	struct e1inp_sign_link *sign_link;
+	struct e1inp_driver *e1inp_driver;
+
+	msg->l2h = msg->data;
+
+	if (!msg->trx || !msg->trx->bts || !msg->trx->bts->oml_link) {
+		fprintf(stderr, "rsl_sendmsg: msg->trx == NULL\n");
+		return -EINVAL;
+	}
+		
+	sign_link = msg->trx->bts->oml_link;
+	msgb_enqueue(&sign_link->tx_list, msg);
+
+	/* notify the driver we have something to write */
+	e1inp_driver = sign_link->ts->line->driver;
+	e1inp_driver->want_write(sign_link->ts);
+
+	return 0;
+}
+
+/* Timeslot */
+
+/* configure and initialize one e1inp_ts */
+int e1inp_ts_config(struct e1inp_ts *ts, struct e1inp_line *line,
+		    enum e1inp_ts_type type)
+{
+	ts->type = type;
+	ts->line = line;
+
+	switch (type) {
+	case E1INP_TS_TYPE_SIGN:
+		INIT_LLIST_HEAD(&ts->sign.sign_links);
+		break;
+	case E1INP_TS_TYPE_TRAU:
+		subchan_mux_init(&ts->trau.mux);
+		ts->trau.demux.out_cb = subch_cb;
+		ts->trau.demux.data = ts;
+		subch_demux_init(&ts->trau.demux);
+		break;
+	default:
+		fprintf(stderr, "unsupported E1 timeslot type %u\n",
+			ts->type);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static struct e1inp_line *e1inp_line_get(u_int8_t e1_nr)
+{
+	struct e1inp_line *e1i_line;
+
+	/* iterate over global list of e1 lines */
+	llist_for_each_entry(e1i_line, &line_list, list) {
+		if (e1i_line->num == e1_nr)
+			return e1i_line;
+	}
+	return NULL;
+}
+
+static struct e1inp_ts *e1inp_ts_get(u_int8_t e1_nr, u_int8_t ts_nr)
+{
+	struct e1inp_line *e1i_line;
+
+	e1i_line = e1inp_line_get(e1_nr);
+	if (!e1i_line)
+		return NULL;
+
+	return &e1i_line->ts[ts_nr-1];
+}
+
+struct subch_mux *e1inp_get_mux(u_int8_t e1_nr, u_int8_t ts_nr)
+{
+	struct e1inp_ts *e1i_ts = e1inp_ts_get(e1_nr, ts_nr);
+
+	if (!e1i_ts)
+		return NULL;
+
+	return &e1i_ts->trau.mux;
+}
+
+/* Signalling Link */
+
+struct e1inp_sign_link *e1inp_lookup_sign_link(struct e1inp_ts *e1i,
+					 	u_int8_t tei, u_int8_t sapi)
+{
+	struct e1inp_sign_link *link;
+
+	llist_for_each_entry(link, &e1i->sign.sign_links, list) {
+		if (link->sapi == sapi && link->tei == tei)
+			return link;
+	}
+
+	return NULL;
+}
+
+/* create a new signalling link in a E1 timeslot */
+
+struct e1inp_sign_link *
+e1inp_sign_link_create(struct e1inp_ts *ts, enum e1inp_sign_type type,
+			struct gsm_bts_trx *trx, u_int8_t tei,
+			u_int8_t sapi)
+{
+	struct e1inp_sign_link *link;
+
+	if (ts->type != E1INP_TS_TYPE_SIGN)
+		return NULL;
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return NULL;
+
+	memset(link, 0, sizeof(*link));
+
+	link->ts = ts;
+	link->type = type;
+	INIT_LLIST_HEAD(&link->tx_list);
+	link->trx = trx;
+	link->tei = sapi;
+
+	llist_add_tail(&link->list, &ts->sign.sign_links);
+
+	return link;
+}
+
+/* the E1 driver tells us he has received something on a TS */
+int e1inp_rx_ts(struct e1inp_ts *ts, struct msgb *msg,
+		u_int8_t tei, u_int8_t sapi)
+{
+	struct e1inp_sign_link *link;
+	int ret;
+
+	switch (ts->type) {
+	case E1INP_TS_TYPE_SIGN:
+		/* FIXME: write pcap packet */
+		/* consult the list of signalling links */
+		link = e1inp_lookup_sign_link(ts, tei, sapi);
+		if (!link) {
+			fprintf(stderr, "didn't find singalling link for "
+				"tei %d, sapi %d\n", tei, sapi);
+			return -EINVAL;
+		}
+		switch (link->type) {
+		case E1INP_SIGN_OML:
+			msg->trx = link->trx;
+			ret = abis_nm_rcvmsg(msg);
+			break;
+		case E1INP_SIGN_RSL:
+			msg->trx = link->trx;
+			ret = abis_rsl_rcvmsg(msg);
+			break;
+		default:
+			ret = -EINVAL;
+			fprintf(stderr, "unknown link type %u\n", link->type);
+			break;
+		}
+		break;
+	case E1INP_TS_TYPE_TRAU:
+		ret = subch_demux_in(&ts->trau.demux, msg->data, msg->len);
+		break;
+	default:
+		ret = -EINVAL;
+		fprintf(stderr, "unknown TS type %u\n", ts->type);
+		break;
+	}
+
+	return ret;
+}
+
+#define TSX_ALLOC_SIZE 4096
+
+/* called by driver if it wants to transmit on a given TS */
+struct msgb *e1inp_tx_ts(struct e1inp_ts *e1i_ts,
+			 struct e1inp_sign_link **sign_link)
+{
+	struct e1inp_sign_link *link;
+	struct msgb *msg = NULL;
+	int len;
+
+	switch (e1i_ts->type) {
+	case E1INP_TS_TYPE_SIGN:
+		/* FIXME: implement this round robin */
+		llist_for_each_entry(link, &e1i_ts->sign.sign_links, list) {
+			msg = msgb_dequeue(&link->tx_list);
+			if (msg) {
+				if (sign_link)
+					*sign_link = link;
+				break;
+			}
+		}
+		break;
+	case E1INP_TS_TYPE_TRAU:
+		msg = msgb_alloc(TSX_ALLOC_SIZE);
+		if (!msg)
+			return NULL;
+		len = subchan_mux_out(&e1i_ts->trau.mux, msg->data, 40);
+		msgb_put(msg, 40);
+		break;
+	default:
+		fprintf(stderr, "unsupported E1 TS type %u\n", e1i_ts->type);
+		return NULL;
+	}
+	return msg;
+}
+
+/* called by driver in case some kind of link state event */
+int e1inp_event(struct e1inp_ts *ts, int evt, u_int8_t tei, u_int8_t sapi)
+{
+	struct e1inp_sign_link *link;
+
+	link = e1inp_lookup_sign_link(ts, tei, sapi);
+	if (!link)
+		return -EINVAL;
+
+	/* FIXME: report further upwards */
+	return input_event(evt, link->type, link->trx);
+}
+
+/* register a driver with the E1 core */
+int e1inp_driver_register(struct e1inp_driver *drv)
+{
+	llist_add_tail(&drv->list, &driver_list);
+	return 0;
+}
+
+/* register a line with the E1 core */
+int e1inp_line_register(struct e1inp_line *line)
+{
+	int i;
+
+	for (i = 0; i < NUM_E1_TS; i++)
+		line->ts[i].num = i+1;
+
+	llist_add_tail(&line->list, &line_list);
+	
+	return 0;
+}
diff --git a/src/input/misdn.c b/src/input/misdn.c
new file mode 100644
index 0000000..8201293
--- /dev/null
+++ b/src/input/misdn.c
@@ -0,0 +1,483 @@
+/* OpenBSC Abis input driver for mISDNuser */
+
+/* (C) 2008-2009 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ *
+ * All Rights Reserved
+ *
+ * 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.
+ *
+ */
+
+#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 <mISDNif.h>
+
+//#define AF_COMPATIBILITY_FUNC
+//#include <compat_af_isdn.h>
+#define AF_ISDN 34
+#define PF_ISDN AF_ISDN
+
+#include <openbsc/select.h>
+#include <openbsc/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>
+
+/* data structure for one E1 interface with A-bis */
+struct mi_e1_handle {
+	/* The mISDN card number of the card we use */
+	int cardnr;
+};
+
+#define TS1_ALLOC_SIZE	300
+
+struct prim_name {
+	unsigned int prim;
+	const char *name;
+};
+
+const struct prim_name prim_names[] = {
+	{ DL_ESTABLISH_IND, "DL_ESTABLISH_IND" },
+	{ DL_ESTABLISH_CNF, "DL_ESTABLISH_CNF" },
+	{ DL_RELEASE_IND, "DL_RELEASE_IND" },
+	{ DL_RELEASE_CNF, "DL_RELEASE_CNF" },
+	{ DL_DATA_IND, "DL_DATA_IND" },
+	{ DL_UNITDATA_IND, "DL_UNITDATA_IND" },
+	{ DL_INFORMATION_IND, "DL_INFORMATION_IND" },
+	{ MPH_ACTIVATE_IND, "MPH_ACTIVATE_IND" },
+	{ MPH_DEACTIVATE_IND, "MPH_DEACTIVATE_IND" },
+};
+
+const char *get_prim_name(unsigned int prim)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(prim_names); i++) {
+		if (prim_names[i].prim == prim)
+			return prim_names[i].name;
+	}
+
+	return "UNKNOWN";
+}
+
+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 = msgb_alloc(TS1_ALLOC_SIZE);
+	struct sockaddr_mISDN l2addr;
+	struct mISDNhead *hh;
+	socklen_t alen;
+	int ret;
+
+	if (!msg)
+		return -ENOMEM;
+
+	hh = (struct mISDNhead *) msg->data;
+
+	alen = sizeof(l2addr);
+	ret = recvfrom(bfd->fd, msg->data, 300, 0,
+		       (struct sockaddr *) &l2addr, &alen);
+	if (ret < 0) {
+		fprintf(stderr, "recvfrom error  %s\n", strerror(errno));
+		return ret;
+	}
+
+	if (alen != sizeof(l2addr))
+		return -EINVAL;
+
+	msgb_put(msg, ret);
+
+	DEBUGP(DMI, "alen =%d, dev(%d) channel(%d) sapi(%d) tei(%d)\n",
+		alen, l2addr.dev, l2addr.channel, l2addr.sapi, l2addr.tei);
+
+	DEBUGP(DMI, "<= len = %d, prim(0x%x) id(0x%x)\n",
+		ret, hh->prim, hh->id);
+
+	DEBUGP(DMI, "got %s:\n", get_prim_name(hh->prim));
+
+	switch (hh->prim) {
+	case DL_INFORMATION_IND:
+		/* mISDN tells us which channel number is allocated for this
+		 * tuple of (SAPI, TEI). */
+		DEBUGP(DMI, "use channel(%d) sapi(%d) tei(%d) for now\n",
+			l2addr.channel, l2addr.sapi, l2addr.tei);
+		link = e1inp_lookup_sign_link(e1i_ts, l2addr.tei, l2addr.sapi);
+		if (!link) {
+			DEBUGPC(DMI, "mISDN message for unknown sign_link\n");
+			free(msg);
+			return -EINVAL;
+		}
+		/* save the channel number in the driver private struct */
+		link->driver.misdn.channel = l2addr.channel;
+		break;
+	case MPH_ACTIVATE_IND:
+		ret = e1inp_event(e1i_ts, EVT_E1_TEI_UP, l2addr.tei, l2addr.sapi);
+		break;
+	case MPH_DEACTIVATE_IND:
+		ret = e1inp_event(e1i_ts, EVT_E1_TEI_DN, l2addr.tei, l2addr.sapi);
+		break;
+	case DL_DATA_IND:
+		DEBUGP(DMI, "got DL_DATA_IND\n");
+		msg->l2h = msg->data + MISDN_HEADER_LEN;
+		if (debug_mask & DMI) { 
+			fprintf(stdout, "RX: ");
+			hexdump(msgb_l2(msg), ret - MISDN_HEADER_LEN);
+		}
+		ret = e1inp_rx_ts(e1i_ts, msg, l2addr.tei, l2addr.sapi);
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+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 sockaddr_mISDN sa;
+	struct msgb *msg;
+	struct mISDNhead *hh;
+	u_int8_t *l2_data;
+	int ret;
+
+	/* get the next msg for this timeslot */
+	msg = e1inp_tx_ts(e1i_ts, &sign_link);
+	if (!msg) {
+		bfd->when &= ~BSC_FD_WRITE;
+		return 0;
+	}
+
+	l2_data = msg->data;
+
+	/* prepend the mISDNhead */
+	hh = (struct mISDNhead *) msgb_push(msg, sizeof(*hh));
+	hh->prim = DL_DATA_REQ;
+
+	if (debug_mask & DMI) {
+		fprintf(stdout, "TX: ");
+		hexdump(l2_data, msg->len - MISDN_HEADER_LEN);
+	}
+
+	/* construct the sockaddr */
+	sa.family = AF_ISDN;
+	sa.sapi = sign_link->sapi;
+	sa.dev = sign_link->tei;
+	sa.channel = sign_link->driver.misdn.channel;
+
+	ret = sendto(bfd->fd, msg->data, msg->len, 0,
+		     (struct sockaddr *)&sa, sizeof(sa));
+	msgb_free(msg);
+
+	/* FIXME: this has to go */
+	usleep(100000);
+
+	return ret;
+}
+
+#define TSX_ALLOC_SIZE 4096
+
+/* FIXME: read from a B channel TS */
+static int handle_tsX_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 msgb *msg = msgb_alloc(TSX_ALLOC_SIZE);
+	struct mISDNhead *hh;
+	int ret;
+
+	if (!msg)
+		return -ENOMEM;
+
+	hh = (struct mISDNhead *) msg->data;
+
+	ret = recv(bfd->fd, msg->data, TSX_ALLOC_SIZE, 0);
+	if (ret < 0) {
+		fprintf(stderr, "recvfrom error  %s\n", strerror(errno));
+		return ret;
+	}
+
+	msgb_put(msg, ret);
+
+	DEBUGP(DMIB, "<= BCHAN len = %d, prim(0x%x) id(0x%x): %s\n",
+		ret, hh->prim, hh->id, get_prim_name(hh->prim));
+
+	switch (hh->prim) {
+	case PH_DATA_IND:
+		msg->l2h = msg->data + MISDN_HEADER_LEN;
+		if (debug_mask & DMIB) {
+			fprintf(stdout, "BCHAN RX: ");
+			hexdump(msgb_l2(msg), ret - MISDN_HEADER_LEN);
+		}
+		ret = e1inp_rx_ts(e1i_ts, msg, 0, 0);
+		break;
+	default:
+		break;
+	}
+	/* FIXME: why do we free signalling msgs in the caller, and trau not? */
+	msgb_free(msg);
+
+	return ret;
+}
+
+#define BCHAN_TX_GRAN	40
+/* write to a B channel TS */
+static int handle_tsX_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 mISDNhead *hh;
+	u_int8_t tx_buf[BCHAN_TX_GRAN + sizeof(*hh)];
+	struct subch_mux *mx = &e1i_ts->trau.mux;
+	int ret;
+
+	hh = (struct mISDNhead *) tx_buf;
+	hh->prim = PH_DATA_REQ;
+
+	subchan_mux_out(mx, tx_buf+sizeof(*hh), BCHAN_TX_GRAN);
+
+	ret = send(bfd->fd, tx_buf, sizeof(*hh) + BCHAN_TX_GRAN, 0);
+	if (ret < sizeof(*hh) + BCHAN_TX_GRAN)
+		DEBUGP(DMIB, "send returns %d instead of %u\n", ret,
+			sizeof(*hh) + BCHAN_TX_GRAN);
+
+	return ret;
+}
+
+/* callback from select.c in case one of the fd's can be read/written */
+static int misdn_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 = &line->ts[idx];
+	int rc = 0;
+
+	switch (e1i_ts->type) {
+	case E1INP_TS_TYPE_SIGN:
+		if (what & BSC_FD_READ)
+			rc = handle_ts1_read(bfd);
+		if (what & BSC_FD_WRITE)
+			rc = handle_ts1_write(bfd);
+		break;
+	case E1INP_TS_TYPE_TRAU:
+		if (what & BSC_FD_READ)
+			rc = handle_tsX_read(bfd);
+		if (what & BSC_FD_WRITE)
+			rc = handle_tsX_write(bfd);
+		break;
+	default:
+		fprintf(stderr, "unknown E1 TS type %u\n", e1i_ts->type);
+		break;
+	}
+
+	return rc;
+}
+
+static int activate_bchan(struct e1inp_line *line, int ts, int act)
+{
+	struct mISDNhead hh;
+	int ret;
+	unsigned int idx = ts-1;
+	struct e1inp_ts *e1i_ts = &line->ts[idx];
+	struct bsc_fd *bfd = &e1i_ts->driver.misdn.fd;
+
+	fprintf(stdout, "activate bchan\n");
+	if (act)
+		hh.prim = PH_ACTIVATE_REQ;
+	else
+		hh.prim = PH_DEACTIVATE_REQ;
+
+	hh.id = MISDN_ID_ANY;
+	ret = sendto(bfd->fd, &hh, sizeof(hh), 0, NULL, 0);
+	if (ret < 0) {
+		fprintf(stdout, "could not send ACTIVATE_RQ %s\n",
+			strerror(errno));
+	}
+
+	return ret;
+}
+
+static int ts_want_write(struct e1inp_ts *e1i_ts)
+{
+	e1i_ts->driver.misdn.fd.when |= BSC_FD_WRITE;
+
+	return 0;
+}
+
+struct e1inp_driver misdn_driver = {
+	.name = "mISDNuser",
+	.want_write = ts_want_write,
+};
+
+static int mi_e1_setup(struct e1inp_line *line)
+{
+	struct mi_e1_handle *e1h = line->driver_data;
+	int ts, ret;
+
+	/* TS0 is CRC4, don't need any fd for it */
+	for (ts = 1; ts < NUM_E1_TS; ts++) {
+		unsigned int idx = ts-1;
+		struct e1inp_ts *e1i_ts = &line->ts[idx];
+		struct bsc_fd *bfd = &e1i_ts->driver.misdn.fd;
+		struct sockaddr_mISDN addr;
+
+		bfd->data = line;
+		bfd->priv_nr = ts;
+		bfd->cb = misdn_fd_cb;
+
+		switch (e1i_ts->type) {
+		case E1INP_TS_TYPE_NONE:
+			continue;
+			break;
+		case E1INP_TS_TYPE_SIGN:
+			bfd->fd = socket(PF_ISDN, SOCK_DGRAM, ISDN_P_LAPD_NT);
+			bfd->when = BSC_FD_READ;
+			break;
+		case E1INP_TS_TYPE_TRAU:
+			bfd->fd = socket(PF_ISDN, SOCK_DGRAM, ISDN_P_B_RAW);
+			bfd->when = BSC_FD_READ | BSC_FD_WRITE;
+			break;
+		}
+
+		if (bfd->fd < 0) {
+			fprintf(stderr, "could not open socket %s\n",
+				strerror(errno));
+			return bfd->fd;
+		}
+
+		memset(&addr, 0, sizeof(addr));
+		addr.family = AF_ISDN;
+		addr.dev = e1h->cardnr;
+		switch (e1i_ts->type) {
+		case E1INP_TS_TYPE_SIGN:
+			addr.channel = 0;
+			/* SAPI not supported yet in kernel */
+			//addr.sapi = e1inp_ts->sign.sapi;
+			addr.sapi = 0;
+			addr.tei = GROUP_TEI;
+			break;
+		case E1INP_TS_TYPE_TRAU:
+			addr.channel = ts;
+			break;
+		default:
+			DEBUGP(DMI, "unsupported E1 TS type: %u\n",
+				e1i_ts->type);
+			break;
+		}
+
+		ret = bind(bfd->fd, (struct sockaddr *) &addr, sizeof(addr));
+		if (ret < 0) {
+			fprintf(stderr, "could not bind l2 socket %s\n",
+				strerror(errno));
+			return -EIO;
+		}
+
+		/* FIXME: only activate B-Channels once we start to
+		 * use them to conserve CPU power */
+		if (e1i_ts->type == E1INP_TS_TYPE_TRAU)
+			activate_bchan(line, ts, 1);
+
+		ret = bsc_register_fd(bfd);
+		if (ret < 0) {
+			fprintf(stderr, "could not register FD: %s\n",
+				strerror(ret));
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+int mi_setup(int cardnr,  struct e1inp_line *line)
+{
+	struct mi_e1_handle *e1h;
+	int sk, ret, cnt;
+	struct mISDN_devinfo devinfo;
+
+	/* register the driver with the core */
+	/* FIXME: do this in the plugin initializer function */
+	ret = e1inp_driver_register(&misdn_driver);
+	if (ret)
+		return ret;
+
+	/* create the actual line instance */
+	/* FIXME: do this independent of driver registration */
+	e1h = malloc(sizeof(*e1h));
+	memset(e1h, 0, sizeof(*e1h));
+
+	e1h->cardnr = cardnr;
+
+	line->driver = &misdn_driver;
+	line->driver_data = e1h;
+
+	/* open the ISDN card device */
+	sk = socket(PF_ISDN, SOCK_RAW, ISDN_P_BASE);
+	if (sk < 0) {
+		fprintf(stderr, "could not open socket %s\n", strerror(errno));
+		return sk;
+	}
+
+	ret = ioctl(sk, IMGETCOUNT, &cnt);
+	if (ret) {
+		fprintf(stderr, "error getting interf count: %s\n",
+			strerror(errno));
+		close(sk);
+		return -ENODEV;
+	}
+	//DEBUGP(DMI,"%d device%s found\n", cnt, (cnt==1)?"":"s");
+	printf("%d device%s found\n", cnt, (cnt==1)?"":"s");
+#if 1
+	devinfo.id = e1h->cardnr;
+	ret = ioctl(sk, IMGETDEVINFO, &devinfo);
+	if (ret < 0) {
+		fprintf(stdout, "error getting info for device %d: %s\n",
+			e1h->cardnr, strerror(errno));
+		return -ENODEV;
+	}
+	fprintf(stdout, "        id:             %d\n", devinfo.id);
+	fprintf(stdout, "        Dprotocols:     %08x\n", devinfo.Dprotocols);
+	fprintf(stdout, "        Bprotocols:     %08x\n", devinfo.Bprotocols);
+	fprintf(stdout, "        protocol:       %d\n", devinfo.protocol);
+	fprintf(stdout, "        nrbchan:        %d\n", devinfo.nrbchan);
+	fprintf(stdout, "        name:           %s\n", devinfo.name);
+#endif
+
+	ret = mi_e1_setup(line);
+	if (ret)
+		return ret;
+
+	return e1inp_line_register(line);
+}
diff --git a/src/subchan_demux.c b/src/subchan_demux.c
index da1b090..78ba2da 100644
--- a/src/subchan_demux.c
+++ b/src/subchan_demux.c
@@ -1,4 +1,4 @@
-/* A E1 sub-channel demultiplexer with TRAU frame sync */
+/* A E1 sub-channel (de)multiplexer with TRAU frame sync */
 
 /* (C) 2009 by Harald Welte <laforge@gnumonks.org>
  * All Rights Reserved
@@ -26,8 +26,9 @@
 #include <errno.h>
 
 #include <openbsc/subchan_demux.h>
+#include <openbsc/trau_frame.h>
 
-static inline void append_bit(struct subch *sch, u_int8_t bit)
+static inline void append_bit(struct demux_subch *sch, u_int8_t bit)
 {
 	sch->out_bitbuf[sch->out_idx++] = bit;
 }
@@ -37,7 +38,7 @@
 
 /* check if we have just completed the 16 bit zero sync header,
  * in accordance with GSM TS 08.60 Chapter 4.8.1 */
-static int sync_hdr_complete(struct subch *sch)
+static int sync_hdr_complete(struct demux_subch *sch)
 {
 	int rc;
 	int bits_at_end = 0;
@@ -62,7 +63,7 @@
 }
 
 /* resynchronize to current location */
-static void resync_to_here(struct subch *sch)
+static void resync_to_here(struct demux_subch *sch)
 {
 #if 0
 	u_int8_t tmp[TRAU_FRAME_BITS];
@@ -98,7 +99,7 @@
 
 	dmx->chan_activ = 0;
 	for (i = 0; i < NR_SUBCH; i++) {
-		struct subch *sch = &dmx->subch[i];
+		struct demux_subch *sch = &dmx->subch[i];
 		sch->out_idx = 0;
 		memset(sch->out_bitbuf, 0xff, sizeof(sch->out_bitbuf));
 	}
@@ -119,7 +120,7 @@
 		u_int8_t inbyte = data[i];
 
 		for (c = 0; c < NR_SUBCH; c++) {
-			struct subch *sch = &dmx->subch[c];
+			struct demux_subch *sch = &dmx->subch[c];
 			u_int8_t bit;
 
 			/* ignore inactive subchannels */
@@ -177,3 +178,134 @@
 	dmx->chan_activ &= ~(1 << subch);
 	return 0;
 }
+
+/* MULTIPLEXER */
+
+static int alloc_add_idle_frame(struct subch_mux *mx, int sch_nr)
+{
+	/* FIXME: allocate and initialize with idle pattern */
+	return subchan_mux_enqueue(mx, sch_nr, trau_idle_frame(),
+				   TRAU_FRAME_BITS);
+}
+
+/* return the requested number of bits from the specified subchannel */
+static int get_subch_bits(struct subch_mux *mx, int subch,
+			  u_int8_t *bits, int num_requested)
+{
+	struct mux_subch *sch = &mx->subch[subch];
+	int num_bits = 0;
+
+	while (num_bits < num_requested) {
+		struct subch_txq_entry *txe;
+		int num_bits_left;
+		int num_bits_thistime;
+
+		/* make sure we have a valid entry at top of tx queue.
+		 * if not, add an idle frame */
+		if (llist_empty(&sch->tx_queue))	
+			alloc_add_idle_frame(mx, subch);
+	
+		if (llist_empty(&sch->tx_queue))
+			return -EIO;
+
+		txe = llist_entry(&sch->tx_queue, struct subch_txq_entry, list);
+		num_bits_left = txe->bit_len - txe->next_bit;
+
+		if (num_bits_left < num_requested)
+			num_bits_thistime = num_bits_left;
+		else
+			num_bits_thistime = num_requested;
+
+		/* pull the bits from the txe */
+		memcpy(bits + num_bits, txe->bits + txe->next_bit, num_requested);
+		txe->next_bit += num_bits_thistime;
+
+		/* free the tx_queue entry if it is fully consumed */
+		if (txe->next_bit >= txe->bit_len) {
+			llist_del(&txe->list);
+			free(txe);
+		}
+
+		/* increment global number of bits dequeued */
+		num_bits += num_bits_thistime;
+	}
+
+	return num_requested;
+}
+
+/* compact an array of 8 single-bit bytes into one byte of 8 bits */
+static u_int8_t compact_bits(u_int8_t *bits)
+{
+	u_int8_t ret = 0;
+	int i;
+
+	for (i = 0; i < 8; i++)
+		ret |= (bits[i] ? 1 : 0) << i;
+
+	return ret;
+}
+
+/* obtain a single output byte from the subchannel muxer */
+static int mux_output_byte(struct subch_mux *mx, u_int8_t *byte)
+{
+	u_int8_t bits[8];
+	int rc;
+
+	/* combine two bits of every subchan */
+	rc = get_subch_bits(mx, 0, &bits[0], 2);
+	rc = get_subch_bits(mx, 1, &bits[2], 2);
+	rc = get_subch_bits(mx, 2, &bits[4], 2);
+	rc = get_subch_bits(mx, 3, &bits[6], 2);
+
+	if (!rc)
+		*byte = compact_bits(bits);
+
+	return rc;
+}
+
+/* Request the output of some muxed bytes from the subchan muxer */
+int subchan_mux_out(struct subch_mux *mx, u_int8_t *data, int len)
+{
+	int i;
+
+	for (i = 0; i < len; i++) {
+		int rc;
+		rc = mux_output_byte(mx, &data[i]);
+		if (rc < 0)
+			break;
+	}
+	return i;
+}
+
+/* enqueue some data into the tx_queue of a given subchannel */
+int subchan_mux_enqueue(struct subch_mux *mx, int s_nr, const u_int8_t *data,
+			int len)
+{
+	struct mux_subch *sch = &mx->subch[s_nr];
+	struct subch_txq_entry *tqe = malloc(sizeof(*tqe) + len);
+
+	if (!tqe)
+		return -ENOMEM;
+
+	memset(tqe, 0, sizeof(*tqe));
+	tqe->bit_len = len;
+	memcpy(tqe->bits, data, len);
+
+	llist_add(&tqe->list, &sch->tx_queue);
+
+	return 0;
+}
+
+/* initialize one subchannel muxer instance */
+int subchan_mux_init(struct subch_mux *mx)
+{
+	int i;
+
+	memset(mx, 0, sizeof(*mx));
+	for (i = 0; i < NR_SUBCH; i++) {
+		struct mux_subch *sch = &mx->subch[i];
+		INIT_LLIST_HEAD(&sch->tx_queue);
+	}
+
+	return 0;
+}
diff --git a/src/trau_frame.c b/src/trau_frame.c
index 9d7e517..4b02c7b 100644
--- a/src/trau_frame.c
+++ b/src/trau_frame.c
@@ -26,6 +26,7 @@
 #include <errno.h>
 
 #include <openbsc/trau_frame.h>
+#include <openbsc/subchan_demux.h>
 
 static u_int32_t get_bits(const u_int8_t *bitbuf, int offset, int num)
 {
@@ -192,6 +193,9 @@
 	memcpy(trau_bits + 305, fr->d_bits + d_idx, 5);
 	/* C16 .. C21 */
 	memcpy(trau_bits+310, fr->c_bits+15, 6);
+
+	/* FIXME: handle timing adjustment */
+
 	/* T1 .. T4 */
 	memcpy(trau_bits+316, fr->t_bits+0, 4);
 }
@@ -230,3 +234,21 @@
 
 	return 0;
 }
+
+static struct decoded_trau_frame fr_idle_frame = {
+	.c_bits = { 0, 1, 1, 1, 0 },	/* IDLE DOWNLINK 3.5.5 */
+	.t_bits = { 1, 1, 1, 1 },
+};
+static u_int8_t encoded_idle_frame[TRAU_FRAME_BITS];
+static int dbits_initted;
+
+u_int8_t *trau_idle_frame(void)
+{
+	/* only initialize during the first call */
+	if (!dbits_initted) {
+		/* set all D-bits to 1 */
+		memset(&fr_idle_frame.d_bits, 0x01, 260);
+		encode_fr(encoded_idle_frame, &fr_idle_frame);
+	}
+	return encoded_idle_frame;
+}
diff --git a/src/trau_mux.c b/src/trau_mux.c
new file mode 100644
index 0000000..753d01f
--- /dev/null
+++ b/src/trau_mux.c
@@ -0,0 +1,109 @@
+/* Simple TRAU frame reflector to route voice calls */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * 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.
+ *
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include <openbsc/gsm_data.h>
+#include <openbsc/trau_frame.h>
+#include <openbsc/trau_mux.h>
+#include <openbsc/subchan_demux.h>
+#include <openbsc/e1_input.h>
+
+struct map_entry {
+	struct llist_head list;
+	struct gsm_e1_subslot src, dst;
+};
+
+static LLIST_HEAD(ss_map);
+
+/* map one particular subslot to another subslot */
+int trau_mux_map(const struct gsm_e1_subslot *src,
+		 const struct gsm_e1_subslot *dst)
+{
+	struct map_entry *me = malloc(sizeof(*me));
+	if (!me)
+		return -ENOMEM;
+
+	memcpy(&me->src, src, sizeof(me->src));
+	memcpy(&me->dst, dst, sizeof(me->dst));
+	llist_add(&me->list, &ss_map);
+
+	return 0;
+}
+
+/* unmap one particular subslot from another subslot */
+int trau_mux_unmap(const struct gsm_e1_subslot *ss)
+{
+	struct map_entry *me, *me2;
+
+	llist_for_each_entry_safe(me, me2, &ss_map, list) {
+		if (!memcmp(&me->src, ss, sizeof(*ss)) ||
+		    !memcmp(&me->dst, ss, sizeof(*ss))) {
+			llist_del(&me->list);
+			return 0;
+		}
+	}
+	return -ENOENT;
+}
+
+/* look-up an enty in the TRAU mux map */
+static struct gsm_e1_subslot *
+lookup_trau_mux_map(const struct gsm_e1_subslot *src)
+{
+	struct map_entry *me;
+
+	llist_for_each_entry(me, &ss_map, list) {
+		if (!memcmp(&me->src, src, sizeof(*src)))
+			return &me->dst;
+		if (!memcmp(&me->dst, src, sizeof(*src)))
+			return &me->src;
+	}
+	return NULL;
+}
+
+/* we get called by subchan_demux */
+int trau_mux_input(struct gsm_e1_subslot *src_e1_ss,
+		   const u_int8_t *trau_bits, int num_bits)
+{
+	struct decoded_trau_frame tf;
+	u_int8_t trau_bits_out[TRAU_FRAME_BITS];
+	struct gsm_e1_subslot *dst_e1_ss = lookup_trau_mux_map(src_e1_ss);
+	struct subch_mux *mx;
+
+	if (!dst_e1_ss)
+		return -EINVAL;
+
+	mx = e1inp_get_mux(dst_e1_ss->e1_nr, dst_e1_ss->e1_ts);
+	if (!mx)
+		return -EINVAL;
+
+	/* decode TRAU, change it to downlink, re-encode */
+	decode_trau_frame(&tf, trau_bits);
+	trau_frame_up2down(&tf);
+	encode_trau_frame(trau_bits_out, &tf);
+
+	/* and send it to the muxer */
+	return subchan_mux_enqueue(mx, dst_e1_ss->e1_ts_ss, trau_bits_out,
+				   TRAU_FRAME_BITS);
+}