diff --git a/include/osmocom/abis/Makefile.am b/include/osmocom/abis/Makefile.am
new file mode 100644
index 0000000..8bdcc96
--- /dev/null
+++ b/include/osmocom/abis/Makefile.am
@@ -0,0 +1,3 @@
+osmoabis_HEADERS = e1_input.h subchan_demux.h ipaccess.h trau_frame.h
+
+osmoabisdir = $(includedir)/osmocom/gsm/abis
diff --git a/include/osmocom/abis/e1_input.h b/include/osmocom/abis/e1_input.h
new file mode 100644
index 0000000..c5a4137
--- /dev/null
+++ b/include/osmocom/abis/e1_input.h
@@ -0,0 +1,225 @@
+#ifndef _E1_INPUT_H
+#define _E1_INPUT_H
+
+#include <stdlib.h>
+#include <netinet/in.h>
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <osmocom/abis/subchan_demux.h>
+
+#define NUM_E1_TS   32
+
+enum e1inp_sign_type {
+	E1INP_SIGN_NONE,
+	E1INP_SIGN_OML,
+	E1INP_SIGN_RSL,
+};
+const char *e1inp_signtype_name(enum e1inp_sign_type tp);
+
+struct e1inp_ts;
+
+struct e1inp_sign_link {
+	/* list of signalling links */
+	struct llist_head list;
+
+	/* to which timeslot do we belong? */
+	struct e1inp_ts *ts;
+
+	enum e1inp_sign_type type;
+
+	/* trx for msg->trx of received msgs */	
+	struct gsm_bts_trx *trx;
+
+	/* msgb queue of to-be-transmitted msgs */
+	struct llist_head tx_list;
+
+	/* SAPI and TEI on the E1 TS */
+	uint8_t sapi;
+	uint8_t tei;
+
+	union {
+		struct {
+			uint8_t channel;
+		} misdn;
+	} driver;
+};
+
+enum e1inp_ts_type {
+	E1INP_TS_TYPE_NONE,
+	E1INP_TS_TYPE_SIGN,
+	E1INP_TS_TYPE_TRAU,
+};
+const char *e1inp_tstype_name(enum e1inp_ts_type tp);
+
+/* A timeslot in the E1 interface */
+struct e1inp_ts {
+	enum e1inp_ts_type type;
+	int num;
+
+	/* to which line do we belong ? */
+	struct e1inp_line *line;
+
+	union {
+		struct {
+			/* list of all signalling links on this TS */
+			struct llist_head sign_links;
+			/* delay for the queue */
+			int delay;
+			/* timer when to dequeue next frame */
+			struct osmo_timer_list tx_timer;
+		} sign;
+		struct {
+			/* subchannel demuxer for frames from E1 */
+			struct subch_demux demux;
+			/* subchannel muxer for frames to E1 */
+			struct subch_mux mux;
+		} trau;
+	};
+	union {
+		struct {
+			/* mISDN driver has one fd for each ts */
+			struct osmo_fd fd;
+		} misdn;
+		struct {
+			/* ip.access driver has one fd for each ts */
+			struct osmo_fd fd;
+		} ipaccess;
+		struct {
+			/* DAHDI driver has one fd for each ts */
+			struct osmo_fd fd;
+			struct lapd_instance *lapd;
+		} dahdi;
+	} driver;
+};
+
+struct gsm_e1_subslot {
+	/* Number of E1 link */
+	uint8_t e1_nr;
+	/* Number of E1 TS inside E1 link */
+	uint8_t e1_ts;
+	/* Sub-slot within the E1 TS, 0xff if full TS */
+	uint8_t e1_ts_ss;
+};
+
+enum e1inp_line_role {
+	E1INP_LINE_R_NONE,
+	E1INP_LINE_R_BSC,
+	E1INP_LINE_R_BTS,
+	E1INP_LINE_R_MAX
+};
+
+struct e1inp_driver {
+	struct llist_head list;
+	const char *name;
+	int (*want_write)(struct e1inp_ts *ts);
+	int (*line_update)(struct e1inp_line *line, enum e1inp_line_role role);
+	int default_delay;
+};
+
+struct e1inp_line {
+	struct llist_head list;
+	int refcnt;
+
+	unsigned int num;
+	const char *name;
+
+	/* array of timestlots */
+	struct e1inp_ts ts[NUM_E1_TS];
+
+	int (*rx)(struct msgb *msg, struct e1inp_ts *ts);
+	int (*rx_err)(int error);
+
+	struct e1inp_driver *driver;
+	void *driver_data;
+};
+
+/* SS_INPUT signals */
+enum signal_input {
+	S_INP_NONE,
+	S_INP_TEI_UP,
+	S_INP_TEI_DN,
+	S_INP_LINE_INIT,
+	S_INP_LINE_ALARM,
+	S_INP_LINE_NOALARM,
+};
+
+/* register a driver with the E1 core */
+int e1inp_driver_register(struct e1inp_driver *drv);
+
+/* fine a previously registered driver */
+struct e1inp_driver *e1inp_driver_find(const char *name);
+
+/* register a line with the E1 core */
+int e1inp_line_register(struct e1inp_line *line);
+
+/* get a line by its ID */
+struct e1inp_line *e1inp_line_get(uint8_t e1_nr);
+
+/* create a line in the E1 input core */
+struct e1inp_line *e1inp_line_create(uint8_t e1_nr, const char *driver_name, int (*rx)(struct msgb *msg, struct e1inp_ts *ts), int (*rx_err)(int error));
+
+/* find a sign_link for given TEI and SAPI in a TS */
+struct e1inp_sign_link *
+e1inp_lookup_sign_link(struct e1inp_ts *ts, uint8_t tei,
+			uint8_t sapi);
+
+/* 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, uint8_t tei,
+			uint8_t sapi);
+
+/* configure and initialize one e1inp_ts */
+int e1inp_ts_config_sign(struct e1inp_ts *ts, struct e1inp_line *line);
+int e1inp_ts_config_trau(struct e1inp_ts *ts, struct e1inp_line *line,
+                         int (*subch_cb)(struct subch_demux *dmx, int ch,
+                                         uint8_t *data, int len, void *_priv));
+
+/* Call from the Stack: configuration of this TS has changed */
+int e1inp_update_ts(struct e1inp_ts *ts);
+
+/* Receive a packet from the E1 driver */
+int e1inp_rx_ts(struct e1inp_ts *ts, struct msgb *msg,
+		uint8_t tei, uint8_t sapi);
+
+/* 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);
+
+/* called by driver in case some kind of link state event */
+int e1inp_event(struct e1inp_ts *ts, int evt, uint8_t tei, uint8_t sapi);
+
+/* Write LAPD frames to the fd. */
+void e1_set_pcap_fd(int fd);
+
+/* called by TRAU muxer to obtain the destination mux entity */
+struct subch_mux *e1inp_get_mux(uint8_t e1_nr, uint8_t ts_nr);
+
+void e1inp_sign_link_destroy(struct e1inp_sign_link *link);
+int e1inp_line_update(struct e1inp_line *line, enum e1inp_line_role role);
+
+struct gsm_network;
+int ipaccess_setup(struct gsm_network *gsmnet);
+int hsl_setup(struct gsm_network *gsmnet);
+
+extern struct llist_head e1inp_driver_list;
+extern struct llist_head e1inp_line_list;
+
+int e1inp_vty_init(void);
+void e1inp_init(void);
+
+int _abis_nm_sendmsg(struct msgb *msg, int to_trx_oml);
+
+/* XXX */
+struct input_signal_data {
+	int link_type;
+	uint8_t tei;
+	uint8_t sapi;
+	struct gsm_bts_trx *trx;
+	struct e1inp_line *line;
+};
+
+#endif /* _E1_INPUT_H */
diff --git a/include/osmocom/abis/ipaccess.h b/include/osmocom/abis/ipaccess.h
new file mode 100644
index 0000000..2792572
--- /dev/null
+++ b/include/osmocom/abis/ipaccess.h
@@ -0,0 +1,93 @@
+#ifndef _OSMO_PROTO_IPACCESS_H
+#define _OSMO_PROTO_IPACCESS_H
+
+#include <stdint.h>
+
+#define IPA_TCP_PORT_OML	3002
+#define IPA_TCP_PORT_RSL	3003
+
+struct ipaccess_head {
+	uint16_t len;	/* network byte order */
+	uint8_t proto;
+	uint8_t data[0];
+} __attribute__ ((packed));
+
+struct ipaccess_head_ext {
+	uint8_t proto;
+	uint8_t data[0];
+} __attribute__ ((packed));
+
+enum ipaccess_proto {
+	IPAC_PROTO_RSL		= 0x00,
+	IPAC_PROTO_IPACCESS	= 0xfe,
+	IPAC_PROTO_SCCP		= 0xfd,
+	IPAC_PROTO_OML		= 0xff,
+
+
+	/* OpenBSC extensions */
+	IPAC_PROTO_OSMO		= 0xee,
+	IPAC_PROTO_MGCP_OLD	= 0xfc,
+};
+
+enum ipaccess_proto_ext {
+	IPAC_PROTO_EXT_CTRL	= 0x00,
+	IPAC_PROTO_EXT_MGCP	= 0x01,
+	IPAC_PROTO_EXT_LAC	= 0x02,
+};
+
+enum ipaccess_msgtype {
+	IPAC_MSGT_PING		= 0x00,
+	IPAC_MSGT_PONG		= 0x01,
+	IPAC_MSGT_ID_GET	= 0x04,
+	IPAC_MSGT_ID_RESP	= 0x05,
+	IPAC_MSGT_ID_ACK	= 0x06,
+
+	/* OpenBSC extension */
+	IPAC_MSGT_SCCP_OLD	= 0xff,
+};
+
+enum ipaccess_id_tags {
+	IPAC_IDTAG_SERNR		= 0x00,
+	IPAC_IDTAG_UNITNAME		= 0x01,
+	IPAC_IDTAG_LOCATION1		= 0x02,
+	IPAC_IDTAG_LOCATION2		= 0x03,
+	IPAC_IDTAG_EQUIPVERS		= 0x04,
+	IPAC_IDTAG_SWVERSION		= 0x05,
+	IPAC_IDTAG_IPADDR		= 0x06,
+	IPAC_IDTAG_MACADDR		= 0x07,
+	IPAC_IDTAG_UNIT			= 0x08,
+};
+
+/*
+ * Firmware specific header
+ */
+struct sdp_firmware {
+	char magic[4];
+	char more_magic[2];
+	uint16_t more_more_magic;
+	uint32_t header_length;
+	uint32_t file_length;
+	char sw_part[20];
+	char text1[64];
+	char time[12];
+	char date[14];
+	char text2[10];
+	char version[20];
+	uint16_t table_offset;
+	/* stuff i don't know */
+} __attribute__((packed));
+
+struct sdp_header_entry {
+	uint16_t something1;
+	char text1[64];
+	char time[12];
+	char date[14];
+	char text2[10];
+	char version[20];
+	uint32_t length;
+	uint32_t addr1;
+	uint32_t addr2;
+	uint32_t start;
+} __attribute__((packed));
+
+#endif /* _OSMO_PROTO_IPACCESS_H */
diff --git a/include/osmocom/abis/subchan_demux.h b/include/osmocom/abis/subchan_demux.h
new file mode 100644
index 0000000..b71c856
--- /dev/null
+++ b/include/osmocom/abis/subchan_demux.h
@@ -0,0 +1,101 @@
+#ifndef _SUBCH_DEMUX_H
+#define _SUBCH_DEMUX_H
+/* A E1 sub-channel (de)multiplexer with TRAU frame sync */
+
+/* (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 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 <stdint.h>
+#include <osmocom/core/linuxlist.h>
+
+#define NR_SUBCH	4
+#define TRAU_FRAME_SIZE	40
+#define TRAU_FRAME_BITS	(TRAU_FRAME_SIZE*8)
+
+/***********************************************************************/
+/* DEMULTIPLEXER */
+/***********************************************************************/
+
+struct demux_subch {
+	uint8_t out_bitbuf[TRAU_FRAME_BITS];
+	uint16_t out_idx; /* next bit to be written in out_bitbuf */
+	/* number of consecutive zeros that we have received (for sync) */
+	unsigned int consecutive_zeros;
+	/* are we in TRAU frame sync or not? */
+	unsigned int in_sync;
+};
+
+struct subch_demux {
+	/* bitmask of currently active subchannels */
+	uint8_t chan_activ;
+	/* one demux_subch struct for every subchannel */
+	struct demux_subch subch[NR_SUBCH];
+	/* callback to be called once we have received a complete
+	 * frame on a given subchannel */
+	int (*out_cb)(struct subch_demux *dmx, int ch, uint8_t *data, int len,
+		      void *);
+	/* user-provided data, transparently passed to out_cb() */
+	void *data;
+};
+
+/* initialize one demultiplexer instance */
+int subch_demux_init(struct subch_demux *dmx);
+
+/* feed 'len' number of muxed bytes into the demultiplexer */
+int subch_demux_in(struct subch_demux *dmx, uint8_t *data, int len);
+
+/* activate decoding/processing for one subchannel */
+int subch_demux_activate(struct subch_demux *dmx, int subch);
+
+/* deactivate decoding/processing for one subchannel */
+int subch_demux_deactivate(struct subch_demux *dmx, int subch);
+
+/***********************************************************************/
+/* MULTIPLEXER */
+/***********************************************************************/
+
+/* one element in the tx_queue of a muxer sub-channel */
+struct subch_txq_entry {
+	struct llist_head list;
+
+	unsigned int bit_len;	/* total number of bits in 'bits' */
+	unsigned int next_bit;	/* next bit to be transmitted */
+
+	uint8_t bits[0];	/* one bit per byte */
+};
+
+struct mux_subch {
+	struct llist_head tx_queue;
+};
+
+/* structure representing one instance of the subchannel muxer */
+struct subch_mux {
+	struct mux_subch subch[NR_SUBCH];
+};
+
+/* initialize a subchannel muxer instance */
+int subchan_mux_init(struct subch_mux *mx);
+
+/* request the output of 'len' multiplexed bytes */
+int subchan_mux_out(struct subch_mux *mx, uint8_t *data, int len);
+
+/* enqueue some data into one sub-channel of the muxer */
+int subchan_mux_enqueue(struct subch_mux *mx, int s_nr, const uint8_t *data,
+			int len);
+
+#endif /* _SUBCH_DEMUX_H */
diff --git a/include/osmocom/abis/trau_frame.h b/include/osmocom/abis/trau_frame.h
new file mode 100644
index 0000000..a76da33
--- /dev/null
+++ b/include/osmocom/abis/trau_frame.h
@@ -0,0 +1,63 @@
+#ifndef _TRAU_FRAME_H
+#define _TRAU_FRAME_H
+/* TRAU frame handling according to GSM TS 08.60 */
+
+/* (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 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 <stdint.h>
+
+/* 21 for FR/EFR, 25 for AMR, 15 for OM, 15 for data, 13 for E-data, 21 idle */
+#define MAX_C_BITS	25
+/* 260 for FR/EFR, 256 for AMR, 264 for OM, 288 for E-data */
+#define MAX_D_BITS	288
+/* for all speech frames */
+#define MAX_T_BITS	4
+/* for OM */
+#define MAX_S_BITS	6
+/* for E-data */
+#define MAX_M_BITS	2
+
+struct decoded_trau_frame {
+	uint8_t c_bits[MAX_C_BITS];
+	uint8_t d_bits[MAX_D_BITS];
+	uint8_t t_bits[MAX_T_BITS];
+	uint8_t s_bits[MAX_S_BITS];
+	uint8_t m_bits[MAX_M_BITS];
+};
+
+#define TRAU_FT_FR_UP		0x02	/* 0 0 0 1 0 - 3.5.1.1.1 */
+#define TRAU_FT_FR_DOWN		0x1c	/* 1 1 1 0 0 - 3.5.1.1.1 */
+#define TRAU_FT_EFR		0x1a	/* 1 1 0 1 0 - 3.5.1.1.1 */
+#define TRAU_FT_AMR		0x06	/* 0 0 1 1 0 - 3.5.1.2 */
+#define TRAU_FT_OM_UP		0x07	/* 0 0 1 0 1 - 3.5.2 */
+#define TRAU_FT_OM_DOWN		0x1b	/* 1 1 0 1 1 - 3.5.2 */
+#define TRAU_FT_DATA_UP		0x08	/* 0 1 0 0 0 - 3.5.3 */
+#define TRAU_FT_DATA_DOWN	0x16	/* 1 0 1 1 0 - 3.5.3 */
+#define TRAU_FT_D145_SYNC	0x14	/* 1 0 1 0 0 - 3.5.3 */
+#define TRAU_FT_EDATA		0x1f	/* 1 1 1 1 1 - 3.5.4 */
+#define TRAU_FT_IDLE_UP		0x10	/* 1 0 0 0 0 - 3.5.5 */
+#define TRAU_FT_IDLE_DOWN	0x0e	/* 0 1 1 1 0 - 3.5.5 */
+
+
+int decode_trau_frame(struct decoded_trau_frame *fr, const uint8_t *trau_bits);
+int encode_trau_frame(uint8_t *trau_bits, const struct decoded_trau_frame *fr);
+int trau_frame_up2down(struct decoded_trau_frame *fr);
+
+
+#endif /* _TRAU_FRAME_H */