diff --git a/src/Makefile.am b/src/Makefile.am
index 25d58c6..58d3bfa 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,7 +19,7 @@
 #
 
 AUTOMAKE_OPTIONS = subdir-objects
-AM_CPPFLAGS = -I$(top_srcdir)/include $(STD_DEFINES_AND_INCLUDES) $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGB_CFLAGS) $(LIBOSMOCTRL_CFLAGS) $(LIBOSMOGSM_CFLAGS)
+AM_CPPFLAGS = -I$(top_srcdir)/include $(STD_DEFINES_AND_INCLUDES) $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGB_CFLAGS) $(LIBOSMOCTRL_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(LIBOSMOTRAU_CFLAGS)
 
 if ENABLE_SYSMODSP
 AM_CPPFLAGS += -DENABLE_DIRECT_PHY
@@ -33,6 +33,10 @@
 AM_CPPFLAGS += -DENABLE_DIRECT_PHY
 endif
 
+if ENABLE_ER_E1_CCU
+AM_CPPFLAGS += -DENABLE_DIRECT_PHY
+endif
+
 AM_CXXFLAGS = -Wall
 
 noinst_LTLIBRARIES = libgprs.la
@@ -208,12 +212,26 @@
 	osmo-bts-oc2g/oc2gbts.c
 endif
 
+if ENABLE_ER_E1_CCU
+AM_CPPFLAGS += -I$(srcdir)/ericsson-rbs
+
+noinst_HEADERS += \
+	ericsson-rbs/er_ccu_if.h \
+	ericsson-rbs/er_ccu_descr.h
+
+osmo_pcu_SOURCES += \
+	ericsson-rbs/er_ccu_l1_if.c \
+	ericsson-rbs/er_ccu_if.c
+endif
+
 osmo_pcu_LDADD = \
 	libgprs.la \
 	$(LIBOSMOGB_LIBS) \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOCTRL_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
+	$(LIBOSMOABIS_LIBS) \
+	$(LIBOSMOTRAU_LIBS) \
 	-lrt \
 	$(NULL)
 
diff --git a/src/ericsson-rbs/er_ccu_descr.h b/src/ericsson-rbs/er_ccu_descr.h
new file mode 100644
index 0000000..0b56cc0
--- /dev/null
+++ b/src/ericsson-rbs/er_ccu_descr.h
@@ -0,0 +1,49 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <osmocom/abis/e1_input.h>
+#include <osmocom/trau/trau_pcu_ericsson.h>
+
+struct er_ccu_descr;
+struct e1_conn_pars;
+typedef void (er_ccu_empty) (struct er_ccu_descr *ccu_descr);
+typedef void (er_ccu_rx) (struct er_ccu_descr *ccu_descr, const ubit_t *bits, unsigned int num_bits);
+
+struct er_ccu_descr {
+
+	/* E1-line and timeslot (filled in by user) */
+	struct e1_conn_pars *e1_conn_pars;
+
+	/* Callback functions (provided by user) */
+	er_ccu_empty *er_ccu_empty_cb;
+	er_ccu_rx *er_ccu_rx_cb;
+
+	/* I.460 Subslot */
+	struct {
+		struct osmo_i460_schan_desc scd;
+		struct osmo_i460_subchan *schan;
+		struct osmo_fsm_inst *trau_sync_fi;
+		bool ccu_connected;
+	} link;
+
+	/* TRAU Sync state */
+	struct {
+		uint32_t pseq_ccu; /* CCU sequence counter (remote) */
+		uint32_t pseq_pcu; /* PCU sequence counter (local) */
+		uint32_t last_afn_ul; /* Adjusted frame number, uplink */
+		uint32_t last_afn_dl; /* Adjusted frame number, downlink */
+		enum time_adj_val tav; /* Last time adjustment value */
+		bool ul_frame_err; /* True when last uplink TRAU frame was bad */
+		bool ccu_synced; /* True when PCU is in sync with CCU */
+	} sync;
+
+	/* PCU related context */
+	struct {
+		uint8_t trx_no;
+		uint8_t bts_nr;
+		uint8_t ts;
+	} pcu;
+
+
+};
diff --git a/src/ericsson-rbs/er_ccu_if.c b/src/ericsson-rbs/er_ccu_if.c
new file mode 100644
index 0000000..aa659a3
--- /dev/null
+++ b/src/ericsson-rbs/er_ccu_if.c
@@ -0,0 +1,416 @@
+/*
+ * (C) 2022 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * 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 <er_ccu_if.h>
+#include <er_ccu_descr.h>
+#include <string.h>
+#include <errno.h>
+
+#include <osmocom/abis/e1_input.h>
+#include <osmocom/abis/abis.h>
+#include <osmocom/trau/trau_sync.h>
+#include <osmocom/trau/trau_pcu_ericsson.h>
+#include <bts.h>
+#include <gprs_debug.h>
+#include <pcu_l1_if.h>
+
+#define E1_TS_BYTES 160
+#define DEBUG_BITS_MAX 1280
+#define DEBUG_BYTES_MAX 40
+
+#define LOGPCCU(ccu_descr, level, tag, fmt, args...) \
+	LOGP(DE1, level, "E1TS(%u:%u:%u) %s:" fmt, \
+	     ccu_descr->e1_conn_pars->e1_nr, ccu_descr->e1_conn_pars->e1_ts, \
+	     ccu_descr->e1_conn_pars->e1_ts_ss == E1_SUBSLOT_FULL ? 0 : ccu_descr->e1_conn_pars->e1_ts_ss, tag, \
+	     ## args)
+
+struct e1_ts_descr {
+	uint8_t usecount;
+	bool i460_ts_initialized;
+	struct osmo_i460_timeslot i460_ts;
+};
+
+struct e1_line_descr {
+	struct e1_ts_descr e1_ts[NUM_E1_TS - 1];
+};
+
+static struct e1_line_descr e1_lines[32];
+static void *tall_ccu_ctx = NULL;
+
+static const struct e1inp_line_ops dummy_e1_line_ops = {
+	.sign_link_up = NULL,
+	.sign_link_down = NULL,
+	.sign_link = NULL,
+};
+
+/* called by trau frame synchronizer: feed received MAC blocks into PCU */
+static void sync_frame_out_cb(void *user_data, const ubit_t *bits, unsigned int num_bits)
+{
+	struct er_ccu_descr *ccu_descr = user_data;
+
+	if (!bits || num_bits == 0)
+		return;
+
+	LOGPCCU(ccu_descr, LOGL_DEBUG, "I.460-RX", "receiving %u TRAU frame bits from subslot (synchronized): %s...\n",
+		num_bits, osmo_ubit_dump(bits, num_bits > DEBUG_BITS_MAX ? DEBUG_BITS_MAX : num_bits));
+
+	ccu_descr->er_ccu_rx_cb(ccu_descr, bits, num_bits);
+}
+
+/* called by I.460 de-multiplexer: feed output of I.460 demux into TRAU frame sync */
+static void e1_i460_demux_bits_cb(struct osmo_i460_subchan *schan, void *user_data, const ubit_t *bits,
+				  unsigned int num_bits)
+{
+	struct er_ccu_descr *ccu_descr = user_data;
+
+	LOGPCCU(ccu_descr, LOGL_DEBUG, "I.460-RX", "receiving %u TRAU frame bits from subslot: %s...\n", num_bits,
+		osmo_ubit_dump(bits, num_bits > DEBUG_BITS_MAX ? DEBUG_BITS_MAX : num_bits));
+
+	OSMO_ASSERT(ccu_descr->link.trau_sync_fi);
+	osmo_trau_sync_rx_ubits(ccu_descr->link.trau_sync_fi, bits, num_bits);
+
+}
+
+/* called by I.460 de-multiplexer: ensure that sync indications are sent when mux buffer runs empty */
+static void e1_i460_mux_empty_cb(struct osmo_i460_subchan *schan2, void *user_data)
+{
+	struct er_ccu_descr *ccu_descr = user_data;
+
+	LOGPCCU(ccu_descr, LOGL_DEBUG, "I.460-TX", "demux buffer empty\n");
+	ccu_descr->er_ccu_empty_cb(ccu_descr);
+}
+
+/* handle outgoing E1 traffic */
+static void e1_send_ts_frame(struct e1inp_ts *ts)
+{
+	void *ctx = tall_ccu_ctx;
+	struct e1_ts_descr *ts_descr;
+	struct msgb *msg;
+	uint8_t *ptr;
+
+	/* The line number and ts number that arrives here should be clean. */
+	OSMO_ASSERT(ts->line->num < ARRAY_SIZE(e1_lines));
+
+	ts_descr = &e1_lines[ts->line->num].e1_ts[ts->num];
+
+	/* Do not send anything in case the E1 timeslot is not ready. */
+	if (ts_descr->usecount == 0)
+		return;
+
+	/* Get E1 frame from I.460 multiplexer */
+	msg = msgb_alloc_c(ctx, E1_TS_BYTES, "E1-TX-timeslot-bytes");
+	ptr = msgb_put(msg, E1_TS_BYTES);
+	osmo_i460_mux_out(&ts_descr->i460_ts, ptr, E1_TS_BYTES);
+
+	LOGPITS(ts, DE1, LOGL_DEBUG, "E1-TX: sending %u bytes: %s...\n",
+	     msgb_length(msg), osmo_hexdump_nospc(msgb_data(msg),
+						  msgb_length(msg) >
+						  DEBUG_BYTES_MAX ? DEBUG_BYTES_MAX : msgb_length(msg)));
+
+	/* Hand data over to the E1 stack */
+	msgb_enqueue(&ts->raw.tx_queue, msg);
+}
+
+/* Callback function to handle incoming E1 traffic */
+static void e1_recv_cb(struct e1inp_ts *ts, struct msgb *msg)
+{
+	struct e1_ts_descr *ts_descr;
+
+	if (msg->len != E1_TS_BYTES) {
+		LOGPITS(ts, DE1, LOGL_ERROR,
+		     "E1-RX: receiving bad, expected length is %u, actual length is %u!\n",
+		     E1_TS_BYTES, msg->len);
+		msgb_free(msg);
+		return;
+	}
+
+	LOGPITS(ts, DE1, LOGL_DEBUG, "E1-RX: receiving %u bytes: %s ...\n",
+		msg->len, osmo_hexdump_nospc(msg->data, msg->len));
+
+	/* Note: The line number and ts number that arrives here should be clean. */
+	OSMO_ASSERT(ts->line->num < ARRAY_SIZE(e1_lines));
+	ts_descr = &e1_lines[ts->line->num].e1_ts[ts->num];
+
+	/* Hand data over to the I640 demultiplexer. */
+	osmo_i460_demux_in(&ts_descr->i460_ts, msg->data, msg->len);
+
+	/* Trigger sending of pending E1 traffic */
+	e1_send_ts_frame(ts);
+
+	/* e1inp_rx_ts(), the caller of this callback does not free() msgb. */
+	msgb_free(msg);
+}
+
+static struct e1_ts_descr *ts_descr_from_ccu_descr(struct er_ccu_descr *ccu_descr)
+{
+	/* Make sure E1 line number is valid */
+	if (ccu_descr->e1_conn_pars->e1_nr >= ARRAY_SIZE(e1_lines)) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "Invalid E1 line number!\n");
+		return NULL;
+	}
+
+	/* Make sure E1 timeslot number is valid */
+	if (ccu_descr->e1_conn_pars->e1_ts < 1 || ccu_descr->e1_conn_pars->e1_ts > NUM_E1_TS - 1) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "Invalid E1 timeslot number!\n");
+		return NULL;
+	}
+
+	/* Timeslots are only initialized once and will stay open after that. */
+	return &e1_lines[ccu_descr->e1_conn_pars->e1_nr].e1_ts[ccu_descr->e1_conn_pars->e1_ts];
+}
+
+/* Configure an I.460 subslot and add it to the CCU descriptor */
+static int add_i460_subslot(void *ctx, struct er_ccu_descr *ccu_descr)
+{
+	struct e1_ts_descr *ts_descr;
+	enum osmo_tray_sync_pat_id sync_pattern;
+
+	if (ccu_descr->link.schan) {
+		/* NOTE: This is a serious error: subslots should be removed when l1if_close_pdch() is called by the
+		 * PCU. This log line points towards a problem with the PDCH management inside the PCU! */
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "I.460 subslot is already configured -- will not touch it!\n");
+		return -EINVAL;
+	}
+
+	ts_descr = ts_descr_from_ccu_descr(ccu_descr);
+	if (!ts_descr)
+		return -EINVAL;
+	if (ts_descr->usecount == 0) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "E1 timeslot not ready!\n");
+		return -EINVAL;
+	}
+
+	/* Set up I.460 subchannel and connect it to the MUX on the E1 timeslot */
+	if (ccu_descr->e1_conn_pars->e1_ts_ss == E1_SUBSLOT_FULL) {
+		LOGPCCU(ccu_descr, LOGL_INFO, "SETUP", "using 64k subslots\n");
+		ccu_descr->link.scd.rate = OSMO_I460_RATE_64k;
+		ccu_descr->link.scd.demux.num_bits = E1_TS_BYTES * 8;
+		ccu_descr->link.scd.bit_offset = 0;
+		sync_pattern = OSMO_TRAU_SYNCP_64_ER_CCU;
+	} else {
+		LOGPCCU(ccu_descr, LOGL_INFO, "SETUP", "using 16k subslots\n");
+		if (ccu_descr->e1_conn_pars->e1_ts_ss > 3) {
+			LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "Invalid I.460 subslot number!\n");
+			return -EINVAL;
+		}
+		ccu_descr->link.scd.rate = OSMO_I460_RATE_16k;
+		ccu_descr->link.scd.demux.num_bits = E1_TS_BYTES / 4 * 8;
+		ccu_descr->link.scd.bit_offset = ccu_descr->e1_conn_pars->e1_ts_ss * 2;
+		sync_pattern = OSMO_TRAU_SYNCP_16_ER_CCU;
+	}
+
+	ccu_descr->link.scd.demux.out_cb_bits = e1_i460_demux_bits_cb;
+	ccu_descr->link.scd.demux.out_cb_bytes = NULL;
+	ccu_descr->link.scd.demux.user_data = ccu_descr;
+	ccu_descr->link.scd.mux.in_cb_queue_empty = e1_i460_mux_empty_cb;
+	ccu_descr->link.scd.mux.user_data = ccu_descr;
+
+	LOGPCCU(ccu_descr, LOGL_INFO, "SETUP", "adding I.460 subchannel: bit_offset=%u, num_bits=%zu\n",
+		ccu_descr->link.scd.bit_offset, ccu_descr->link.scd.demux.num_bits);
+	ccu_descr->link.schan = osmo_i460_subchan_add(ctx, &ts_descr->i460_ts, &ccu_descr->link.scd);
+	if (!ccu_descr->link.schan) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "adding I.460 subchannel: failed!\n");
+		return -EINVAL;
+	}
+
+	/* Configure TRAU synchronizer */
+	ccu_descr->link.trau_sync_fi = osmo_trau_sync_alloc(tall_ccu_ctx, "trau-sync", sync_frame_out_cb, sync_pattern, ccu_descr);
+	if (!ccu_descr->link.trau_sync_fi) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "adding I.460 TRAU frame sync: failed!\n");
+		return -EINVAL;
+	}
+
+	/* Ericsson uses a different synchronization pattern for MCS9 TRAU frames */
+	if (sync_pattern == OSMO_TRAU_SYNCP_64_ER_CCU)
+		osmo_trau_sync_set_secondary_pat(ccu_descr->link.trau_sync_fi, OSMO_TRAU_SYNCP_64_ER_CCU_MCS9, 1);
+
+	return 0;
+}
+
+/* Remove an I.460 subslot from the CCU descriptor */
+static void del_i460_subslot(struct er_ccu_descr *ccu_descr)
+{
+	if (ccu_descr->link.schan)
+		osmo_i460_subchan_del(ccu_descr->link.schan);
+	ccu_descr->link.schan = NULL;
+	if (ccu_descr->link.trau_sync_fi)
+		osmo_fsm_inst_term(ccu_descr->link.trau_sync_fi, OSMO_FSM_TERM_REGULAR, NULL);
+	ccu_descr->link.trau_sync_fi = NULL;
+
+	memset(&ccu_descr->link.scd, 0, sizeof(ccu_descr->link.scd));
+}
+
+/* Configure an E1 timeslot according to the description in the ccu_descr */
+static int open_e1_timeslot(struct er_ccu_descr *ccu_descr)
+{
+	struct e1inp_line *e1_line;
+	struct e1_ts_descr *ts_descr;
+	int rc;
+
+	/* Find timeslot descriptor and check if the timeslot is already open. */
+	ts_descr = ts_descr_from_ccu_descr(ccu_descr);
+	if (!ts_descr)
+		return -EINVAL;
+	if (ts_descr->usecount > 0) {
+		LOGPCCU(ccu_descr, LOGL_DEBUG, "SETUP", "E1 timeslot already open -- using it as it is!\n");
+		ts_descr->usecount++;
+		return 0;
+	}
+
+	/* Find and set up E1 line */
+	e1_line = e1inp_line_find(ccu_descr->e1_conn_pars->e1_nr);
+	if (!e1_line) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "no such E1 line!\n");
+		return -EINVAL;
+	}
+	e1inp_line_bind_ops(e1_line, &dummy_e1_line_ops);
+
+	/* Set up E1 timeslot */
+	rc = e1inp_ts_config_raw(&e1_line->ts[ccu_descr->e1_conn_pars->e1_ts - 1], e1_line, e1_recv_cb);
+	if (rc < 0) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "configuration of timeslot failed!\n");
+		return -EINVAL;
+	}
+	rc = e1inp_line_update(e1_line);
+	if (rc < 0) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "line update failed!\n");
+		return -EINVAL;
+	}
+
+	/* Make sure the i460 mux is ready */
+	if (!ts_descr->i460_ts_initialized) {
+		osmo_i460_ts_init(&ts_descr->i460_ts);
+		ts_descr->i460_ts_initialized = true;
+	}
+
+	ts_descr->usecount++;
+	OSMO_ASSERT(ts_descr->usecount == 1);
+
+	return 0;
+}
+
+/* Configure an E1 timeslot according to the description in the ccu_descr */
+static int close_e1_timeslot(struct er_ccu_descr *ccu_descr)
+{
+	struct e1inp_line *e1_line;
+	struct e1_ts_descr *ts_descr;
+	int rc;
+
+	/* Find timeslot descriptor and check if the timeslot is still used by another subslot. */
+	ts_descr = ts_descr_from_ccu_descr(ccu_descr);
+	if (!ts_descr)
+		return -EINVAL;
+	if (ts_descr->usecount > 1) {
+		LOGPCCU(ccu_descr, LOGL_DEBUG, "SETUP",
+			"E1 timeslot still in used by another subslot, leaving it open!\n");
+		ts_descr->usecount--;
+		return 0;
+	} else if (ts_descr->usecount == 0) {
+		/* This should not be as it means we close the timeslot too often. */
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "E1 timeslot already closed, leaving it as it is...\n");
+		return -EINVAL;
+	}
+
+	/* Find E1 line */
+	e1_line = e1inp_line_find(ccu_descr->e1_conn_pars->e1_nr);
+	if (!e1_line) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "no such E1 line!\n");
+		return -EINVAL;
+	}
+
+	/* Release E1 timeslot */
+	rc = e1inp_ts_config_none(&e1_line->ts[ccu_descr->e1_conn_pars->e1_ts - 1], e1_line);
+	if (rc < 0) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "failed to disable E1 timeslot!\n");
+		return -EINVAL;
+	}
+	rc = e1inp_line_update(e1_line);
+	if (rc < 0) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "failed to update E1 line!\n");
+		return -EINVAL;
+	}
+
+	ts_descr->usecount--;
+	OSMO_ASSERT(ts_descr->usecount == 0);
+
+	return 0;
+}
+
+int er_ccu_if_open(struct er_ccu_descr *ccu_descr)
+{
+	if (ccu_descr->link.ccu_connected) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP",
+			"cannot connect CCU since it is already connected -- ignored!\n");
+		return 0;
+	}
+
+	if (open_e1_timeslot(ccu_descr) < 0)
+		return -EINVAL;
+
+	if (add_i460_subslot(tall_ccu_ctx, ccu_descr) < 0)
+		return -EINVAL;
+
+	ccu_descr->link.ccu_connected = true;
+	LOGPCCU(ccu_descr, LOGL_DEBUG, "SETUP", "CCU connected.\n");
+	return 0;
+}
+
+void er_ccu_if_close(struct er_ccu_descr *ccu_descr)
+{
+	if (!ccu_descr->link.ccu_connected) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP",
+			"cannot disconnect CCU since it is already disconnected -- ignored!\n");
+		return;
+	}
+
+	del_i460_subslot(ccu_descr);
+	close_e1_timeslot(ccu_descr);
+
+	ccu_descr->link.ccu_connected = false;
+	LOGPCCU(ccu_descr, LOGL_DEBUG, "SETUP", "CCU disconnected.\n");
+}
+
+void er_ccu_if_tx(struct er_ccu_descr *ccu_descr, const ubit_t *bits, unsigned int num_bits)
+{
+	struct msgb *msg;
+	uint8_t *ptr;
+
+	if (!ccu_descr->link.ccu_connected) {
+		LOGPCCU(ccu_descr, LOGL_ERROR, "SETUP", "cannot TX block, CCU is disconnected -- ignored!\n");
+		return;
+	}
+
+	msg = msgb_alloc_c(tall_ccu_ctx, num_bits, "E1-I.460-PCU-IND-frame");
+	ptr = msgb_put(msg, num_bits);
+	memcpy(ptr, bits, num_bits);
+	LOGPCCU(ccu_descr, LOGL_DEBUG, "I.460-TX", "sending %u bits: %s...\n", msgb_length(msg),
+		osmo_ubit_dump(msgb_data(msg), msgb_length(msg) > DEBUG_BITS_MAX ? DEBUG_BITS_MAX : msgb_length(msg)));
+	osmo_i460_mux_enqueue(ccu_descr->link.schan, msg);
+}
+
+void er_ccu_if_init(void *ctx)
+{
+	libosmo_abis_init(ctx);
+	e1inp_vty_init();
+
+	tall_ccu_ctx = talloc_new(ctx);
+	memset(e1_lines, 0, sizeof(e1_lines));
+}
diff --git a/src/ericsson-rbs/er_ccu_if.h b/src/ericsson-rbs/er_ccu_if.h
new file mode 100644
index 0000000..4073530
--- /dev/null
+++ b/src/ericsson-rbs/er_ccu_if.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <stdint.h>
+#include <osmocom/abis/e1_input.h>
+#include "er_ccu_descr.h"
+
+int er_ccu_if_open(struct er_ccu_descr *ccu_descr);
+void er_ccu_if_close(struct er_ccu_descr *ccu_descr);
+void er_ccu_if_tx(struct er_ccu_descr *ccu_descr, const ubit_t *bits, unsigned int num_bits);
+void er_ccu_if_init(void *ctx);
diff --git a/src/ericsson-rbs/er_ccu_l1_if.c b/src/ericsson-rbs/er_ccu_l1_if.c
new file mode 100644
index 0000000..b7dd102
--- /dev/null
+++ b/src/ericsson-rbs/er_ccu_l1_if.c
@@ -0,0 +1,526 @@
+/*
+ * (C) 2022 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * 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 <er_ccu_descr.h>
+#include <er_ccu_if.h>
+
+#include <string.h>
+#include <errno.h>
+
+#include <osmocom/pcu/pcuif_proto.h>
+#include <osmocom/abis/e1_input.h>
+#include <osmocom/abis/abis.h>
+#include <osmocom/abis/e1_input.h>
+#include <osmocom/trau/trau_sync.h>
+#include <osmocom/trau/trau_pcu_ericsson.h>
+#include <osmocom/gsm/gsm0502.h>
+#include <osmocom/core/talloc.h>
+
+#include <bts.h>
+#include <pcu_l1_if.h>
+#include <pcu_l1_if_phy.h>
+
+extern void *tall_pcu_ctx;
+
+const uint8_t fn_inc_table[4] = { 4, 4, 5, 0 };
+const uint8_t blk_nr_table[4] = { 4, 4, 5, 0 };
+
+#define SYNC_CHECK_INTERVAL GSM_TDMA_SUPERFRAME * 8
+
+/* Subtrahend to convert Ericsson adjusted (block ending) fn to regular fn (uplink only) */
+#define AFN_SUBTRAHEND 3
+
+#define LOGPL1IF(ccu_descr, level, tag, fmt, args...)	       \
+	LOGP(DL1IF, level, "%s: PDCH(trx=%u,ts=%u) E1-line(line=%u,ts=%u,ss=%u) " fmt, \
+	     tag, ccu_descr->pcu.trx_no, ccu_descr->pcu.ts, \
+	     ccu_descr->e1_conn_pars->e1_nr, ccu_descr->e1_conn_pars->e1_ts, \
+	     ccu_descr->e1_conn_pars->e1_ts_ss == E1_SUBSLOT_FULL ? 0 : ccu_descr->e1_conn_pars->e1_ts_ss, \
+	     ## args)
+
+/* Calculate GPRS block number from frame number */
+static uint8_t fn_to_block_nr(uint32_t fn)
+{
+	/* Note: See also 3GPP TS 03.64 6.5.7.2.1,
+	 * Mapping on the multiframe structure */
+
+	uint8_t rel_fn;
+	uint8_t super_block;
+	uint8_t local_block;
+
+	rel_fn = fn % 52;
+
+	/* Warn in case of frames that do not belong to a block */
+	if (rel_fn == 12 || rel_fn == 25 || rel_fn == 38 || rel_fn == 51)
+		LOGP(DL1IF, LOGL_ERROR, "Frame number is referencing invalid block!\n");
+
+	super_block = (rel_fn / 13);
+	local_block = rel_fn % 13 / 4;
+	return super_block * 3 + local_block;
+}
+
+static uint32_t fn_dl_advance(uint32_t fn, uint32_t n_blocks)
+{
+	uint32_t i;
+
+	uint8_t inc_fn;
+
+	for (i = 0; i < n_blocks; i++) {
+		inc_fn = fn_inc_table[(fn % 13) / 4];
+		fn = GSM_TDMA_FN_SUM(fn, inc_fn);
+	}
+
+	return fn;
+}
+
+static bool mac_block_is_noise(struct er_gprs_trau_frame *trau_frame)
+{
+	switch (trau_frame->u.ccu_data_ind.cs_hdr) {
+	case CS_OR_HDR_CS1:
+	case CS_OR_HDR_CS2:
+	case CS_OR_HDR_CS3:
+	case CS_OR_HDR_CS4:
+		if (!trau_frame->u.ccu_data_ind.u.gprs.parity_ok)
+			return true;
+		break;
+	case CS_OR_HDR_HDR1:
+	case CS_OR_HDR_HDR2:
+	case CS_OR_HDR_HDR3:
+		if (!trau_frame->u.ccu_data_ind.u.egprs.hdr_good)
+			return true;
+		if (!trau_frame->u.ccu_data_ind.u.egprs.data_good[0]
+		    && !trau_frame->u.ccu_data_ind.u.egprs.data_good[1])
+			return true;
+		break;
+	case CS_OR_HDR_AB:
+		/* We are not interested in receiving access bursts. */
+		return true;
+	}
+
+	/* No noise, this block is interesting for us. */
+	return false;
+}
+
+static void log_data_ind(struct er_ccu_descr *ccu_descr, struct er_gprs_trau_frame *trau_frame, uint32_t afn_ul_comp,
+			 uint32_t afn_dl_comp)
+{
+	switch (trau_frame->u.ccu_data_ind.cs_hdr) {
+	case CS_OR_HDR_CS1:
+	case CS_OR_HDR_CS2:
+	case CS_OR_HDR_CS3:
+	case CS_OR_HDR_CS4:
+		LOGPL1IF(ccu_descr, LOGL_DEBUG, "CCU-DATA-IND",
+			 "tav=%u, dbe=%u, cs_hdr=%u, rx_lev=%u, est_acc_del_dev=%u,"
+			 "block_qual=%u, parity_ok=%u, data=%s<==, afn_ul_comp=%u/%u\n", trau_frame->u.ccu_data_ind.tav,
+			 trau_frame->u.ccu_data_ind.dbe, trau_frame->u.ccu_data_ind.cs_hdr,
+			 trau_frame->u.ccu_data_ind.rx_lev, trau_frame->u.ccu_data_ind.est_acc_del_dev,
+			 trau_frame->u.ccu_data_ind.u.gprs.block_qual, trau_frame->u.ccu_data_ind.u.gprs.parity_ok,
+			 osmo_hexdump_nospc(trau_frame->u.ccu_data_ind.data, trau_frame->u.ccu_data_ind.data_len),
+			 afn_ul_comp, afn_ul_comp % 52);
+		break;
+	case CS_OR_HDR_HDR1:
+	case CS_OR_HDR_HDR2:
+	case CS_OR_HDR_HDR3:
+	case CS_OR_HDR_AB:
+		LOGPL1IF(ccu_descr, LOGL_DEBUG, "CCU-DATA-IND",
+			 "tav=%u, dbe=%u, cs_hdr=%u, rx_lev=%u, est_acc_del_dev=%u,"
+			 "mean_bep=%u, cv_bep=%u, hdr_good=%u, data_good[0]=%u, data_good[1]=%u, data=%s<==, afn_ul_comp=%u/%u\n",
+			 trau_frame->u.ccu_data_ind.tav, trau_frame->u.ccu_data_ind.dbe,
+			 trau_frame->u.ccu_data_ind.cs_hdr, trau_frame->u.ccu_data_ind.rx_lev,
+			 trau_frame->u.ccu_data_ind.est_acc_del_dev, trau_frame->u.ccu_data_ind.u.egprs.mean_bep,
+			 trau_frame->u.ccu_data_ind.u.egprs.cv_bep, trau_frame->u.ccu_data_ind.u.egprs.hdr_good,
+			 trau_frame->u.ccu_data_ind.u.egprs.data_good[0],
+			 trau_frame->u.ccu_data_ind.u.egprs.data_good[1],
+			 osmo_hexdump_nospc(trau_frame->u.ccu_data_ind.data, trau_frame->u.ccu_data_ind.data_len),
+			 afn_ul_comp, afn_ul_comp % 52);
+	}
+}
+
+/* Receive block from CCU */
+static void er_ccu_rx_cb(struct er_ccu_descr *ccu_descr, const ubit_t *bits, unsigned int num_bits)
+{
+	int rc;
+	struct er_gprs_trau_frame trau_frame;
+	uint8_t inc_ul;
+	uint8_t inc_dl;
+	uint32_t afn_ul;
+	uint32_t afn_dl;
+	uint32_t afn_ul_comp;
+	uint32_t afn_dl_comp;
+	struct pcu_l1_meas meas = { 0 };
+	struct gprs_rlcmac_bts *bts;
+	struct gprs_rlcmac_pdch *pdch;
+
+	/* Compute the current frame numbers from the last frame number */
+	inc_ul = fn_inc_table[(ccu_descr->sync.last_afn_ul % 13) / 4];
+	inc_dl = fn_inc_table[(ccu_descr->sync.last_afn_dl % 13) / 4];
+	afn_ul = GSM_TDMA_FN_SUM(ccu_descr->sync.last_afn_ul, inc_ul);
+	afn_dl = GSM_TDMA_FN_SUM(ccu_descr->sync.last_afn_dl, inc_dl);
+
+	/* Compute compensated frame numbers. This will be the framenumbers we
+	 * will use to exchange blocks with the PCU code. The following applies:
+	 *
+	 * 1. The uplink related frame numbers sent by the ericsson CCU refer to the end of a block. This is
+	 *    compensated by subtracting three frames.
+	 * 2. The CCU downlink frame number runs one block past the uplink frame number. This needs to be
+	 *    compesated as well (+1).
+	 * 3. The difference between the local (PCU) and the returned (CCU) pseq counter value is the number of blocks
+	 *    that the PCU must
+	 *    shift its downlink alignment in order to compensate the link latency between PCU and CCU. */
+	afn_ul_comp = GSM_TDMA_FN_SUB(afn_ul, AFN_SUBTRAHEND);
+	afn_dl_comp = afn_dl;
+	afn_dl_comp = fn_dl_advance(afn_dl_comp, GSM_TDMA_FN_DIFF(ccu_descr->sync.pseq_pcu, ccu_descr->sync.pseq_ccu) + 1);
+
+	LOGPL1IF(ccu_descr, LOGL_DEBUG, "CCU-SYNC",
+		 "afn_ul=%u/%u, afn_dl=%u/%u, afn_diff=%u => afn_ul_comp=%u/%u, afn_dl_comp=%u/%u, afn_diff_comp=%u\n",
+		 afn_ul, afn_ul % 52, afn_dl, afn_dl % 52, GSM_TDMA_FN_DIFF(afn_ul, afn_dl), afn_ul_comp,
+		 afn_ul_comp % 52, afn_dl_comp, afn_dl_comp % 52, GSM_TDMA_FN_DIFF(afn_ul_comp, afn_dl_comp));
+
+	LOGPL1IF(ccu_descr, LOGL_DEBUG, "CCU-SYNC", "pseq_pcu=%u, pseq_ccu=%u, pseq_diff=%u\n",
+		 ccu_descr->sync.pseq_pcu, ccu_descr->sync.pseq_ccu, GSM_TDMA_FN_DIFF(ccu_descr->sync.pseq_pcu, ccu_descr->sync.pseq_ccu));
+
+	/* Decode indication from CCU */
+	if (ccu_descr->e1_conn_pars->e1_ts_ss == E1_SUBSLOT_FULL)
+		rc = er_gprs_trau_frame_decode_64k(&trau_frame, bits);
+	else
+		rc = er_gprs_trau_frame_decode_16k(&trau_frame, bits);
+	if (rc < 0) {
+		LOGPL1IF(ccu_descr, LOGL_ERROR, "CCU-XXXX-IND",
+			 "unable to decode uplink TRAU frame, afn_ul_comp=%u/%u\n", afn_ul_comp, afn_ul_comp % 52);
+
+		/* Report to the CCU that there is an issue with uplink TRAU frames, the CCU will then send
+		 * a CCU-SYNC-IND within the next TRAU frame, so we can check if we are still in sync and trigger
+		 * synchronization procedure if necessary. */
+		ccu_descr->sync.ul_frame_err = true;
+		goto skip;
+	}
+
+	switch (trau_frame.type) {
+	case ER_GPRS_TRAU_FT_SYNC:
+		if (trau_frame.u.ccu_sync_ind.pseq != 0x3FFFFF) {
+			LOGPL1IF(ccu_descr, LOGL_DEBUG, "CCU-SYNC-IND",
+				 "tav=%u, dbe=%u, dfe=%u, pseq=%u, afn_ul=%u, afn_dl=%u\n",
+				 trau_frame.u.ccu_sync_ind.tav, trau_frame.u.ccu_sync_ind.dbe,
+				 trau_frame.u.ccu_sync_ind.dfe, trau_frame.u.ccu_sync_ind.pseq,
+				 trau_frame.u.ccu_sync_ind.afn_ul, trau_frame.u.ccu_sync_ind.afn_dl);
+
+			/* Synchronize the current CCU PSEQ state */
+			ccu_descr->sync.pseq_ccu = trau_frame.u.ccu_sync_ind.pseq;
+		} else {
+			LOGPL1IF(ccu_descr, LOGL_DEBUG, "CCU-SYNC-IND",
+				 "tav=%u, dbe=%u, dfe=%u, pseq=(none), afn_ul=%u, afn_dl=%u\n",
+				 trau_frame.u.ccu_sync_ind.tav, trau_frame.u.ccu_sync_ind.dbe,
+				 trau_frame.u.ccu_sync_ind.dfe, trau_frame.u.ccu_sync_ind.afn_ul,
+				 trau_frame.u.ccu_sync_ind.afn_dl);
+		}
+
+		ccu_descr->sync.tav = trau_frame.u.ccu_sync_ind.tav;
+
+		/* Check if we are in sync with the CCU, if not trigger synchronization procedure */
+		if (afn_ul != trau_frame.u.ccu_sync_ind.afn_ul || afn_dl != trau_frame.u.ccu_sync_ind.afn_dl) {
+			if (afn_ul != trau_frame.u.ccu_sync_ind.afn_ul)
+				LOGPL1IF(ccu_descr, LOGL_NOTICE, "CCU-SYNC-IND",
+					 "afn_ul=%u (computed) != afn_ul=%u (sync-ind) => delta=%u\n", afn_ul,
+					 trau_frame.u.ccu_sync_ind.afn_ul,
+					 GSM_TDMA_FN_DIFF(afn_ul, trau_frame.u.ccu_sync_ind.afn_ul));
+			if (afn_dl != trau_frame.u.ccu_sync_ind.afn_dl)
+				LOGPL1IF(ccu_descr, LOGL_NOTICE, "CCU-SYNC-IND",
+					 "afn_dl=%u (computed) != afn_dl=%u (sync-ind) => delta=%u\n", afn_dl,
+					 trau_frame.u.ccu_sync_ind.afn_dl,
+					 GSM_TDMA_FN_DIFF(afn_dl, trau_frame.u.ccu_sync_ind.afn_dl));
+			LOGPL1IF(ccu_descr, LOGL_NOTICE, "CCU-SYNC-IND",
+				 "FN jump detected, lost sync with CCU -- (re)synchronizing...\n");
+			ccu_descr->sync.ccu_synced = false;
+		} else {
+			LOGPL1IF(ccu_descr, LOGL_NOTICE, "CCU-SYNC-IND", "in sync with CCU\n");
+			ccu_descr->sync.ccu_synced = true;
+		}
+
+		/* Overwrite calculated afn_ul and afn_dl with the actual values from the SYNC indication */
+		afn_ul = trau_frame.u.ccu_sync_ind.afn_ul;
+		afn_dl = trau_frame.u.ccu_sync_ind.afn_dl;
+
+		break;
+	case ER_GPRS_TRAU_FT_DATA:
+
+		ccu_descr->sync.tav = trau_frame.u.ccu_data_ind.tav;
+
+		/* Ignore all data indications that contain only noise */
+		if (mac_block_is_noise(&trau_frame))
+			break;
+
+		log_data_ind(ccu_descr, &trau_frame, afn_ul_comp, afn_dl_comp);
+
+		/* Hand received MAC block into PCU */
+		bts = gprs_pcu_get_bts_by_nr(the_pcu, ccu_descr->pcu.bts_nr);
+		if (!bts)
+			break;
+		meas.have_rssi = 1;
+		meas.rssi = rxlev2dbm(trau_frame.u.ccu_data_ind.rx_lev);
+		meas.have_link_qual = 1;
+		meas.link_qual = trau_frame.u.ccu_data_ind.u.gprs.block_qual;
+		pdch = &bts->trx[ccu_descr->pcu.trx_no].pdch[ccu_descr->pcu.ts];
+		rc = pcu_rx_data_ind_pdtch(bts, pdch, trau_frame.u.ccu_data_ind.data,
+					   trau_frame.u.ccu_data_ind.data_len, afn_ul_comp, &meas);
+		break;
+	default:
+		LOGPL1IF(ccu_descr, LOGL_ERROR, "CCU-XXXX-IND", "unhandled CCU indication!\n");
+	}
+
+skip:
+	if (ccu_descr->sync.ccu_synced) {
+		bts = gprs_pcu_get_bts_by_nr(the_pcu, ccu_descr->pcu.bts_nr);
+		if (bts) {
+			/* The PCU timing is locked to the uplink fame number. The downlink frame number is advanced
+			 * into the future so that the line latency is compensated and the frame arrives at the right
+			 * point in time. */
+			pdch = &bts->trx[ccu_descr->pcu.trx_no].pdch[ccu_descr->pcu.ts];
+			pcu_rx_block_time(bts, pdch->trx->arfcn, afn_ul_comp, ccu_descr->pcu.ts);
+			rc = pcu_rx_rts_req_pdtch(bts, ccu_descr->pcu.trx_no, ccu_descr->pcu.ts, afn_dl_comp,
+						  fn_to_block_nr(afn_dl_comp));
+		}
+	}
+
+	/* We do not receive sync indications in every cycle. When traffic is transferred we won't get frame numbers
+	 * from the CCU. In this case we must update the last_afn_ul/dl values from the computed frame numbers
+	 * (see above) */
+	ccu_descr->sync.last_afn_ul = afn_ul;
+	ccu_descr->sync.last_afn_dl = afn_dl;
+	ccu_descr->sync.pseq_pcu++;
+	ccu_descr->sync.pseq_ccu++;
+}
+
+static void er_ccu_empty_cb(struct er_ccu_descr *ccu_descr)
+{
+	struct er_gprs_trau_frame trau_frame;
+	ubit_t trau_frame_encoded[ER_GPRS_TRAU_FRAME_LEN_64K];
+	int rc;
+
+	memset(&trau_frame, 0, sizeof(trau_frame));
+	trau_frame.u.pcu_sync_ind.pseq = ccu_descr->sync.pseq_pcu;
+	trau_frame.u.pcu_sync_ind.tav = ccu_descr->sync.tav;
+	trau_frame.u.pcu_sync_ind.fn_ul = 0x3FFFFF;
+	trau_frame.u.pcu_sync_ind.fn_dl = 0x3FFFFF;
+	trau_frame.u.pcu_sync_ind.fn_ss = 0x3FFFFF;
+	trau_frame.u.pcu_sync_ind.ls = 0x3FFFFF;
+	trau_frame.u.pcu_sync_ind.ss = 0x3FFFFF;
+	trau_frame.type = ER_GPRS_TRAU_FT_SYNC;
+
+	if (ccu_descr->e1_conn_pars->e1_ts_ss == E1_SUBSLOT_FULL)
+		rc = er_gprs_trau_frame_encode_64k(trau_frame_encoded, &trau_frame);
+	else
+		rc = er_gprs_trau_frame_encode_16k(trau_frame_encoded, &trau_frame);
+	if (rc < 0) {
+		LOGPL1IF(ccu_descr, LOGL_ERROR, "PCU-SYNC-IND", "unable to encode TRAU frame\n");
+		return;
+	}
+	LOGPL1IF(ccu_descr, LOGL_DEBUG, "PCU-SYNC-IND", "pseq=%u, tav=%u\n",
+		 trau_frame.u.pcu_sync_ind.pseq, trau_frame.u.pcu_sync_ind.tav);
+	er_ccu_if_tx(ccu_descr, trau_frame_encoded, rc);
+
+	/* Make sure timing adjustment value is reset after use */
+	ccu_descr->sync.tav = TIME_ADJ_NONE;
+}
+
+/* use the length of the block to determine the coding scheme */
+static int cs_hdr_from_len(uint8_t len)
+{
+	switch (len) {
+	case 23:
+		return CS_OR_HDR_CS1;
+	case 34:
+		return CS_OR_HDR_CS2;
+	case 40:
+		return CS_OR_HDR_CS3;
+	case 54:
+		return CS_OR_HDR_CS4;
+	case 27:
+	case 33:
+	case 42:
+	case 49:
+		return CS_OR_HDR_HDR3;
+	case 60:
+	case 78:
+		return CS_OR_HDR_HDR2;
+	case 118:
+	case 142:
+	case 154:
+		return CS_OR_HDR_HDR1;
+	default:
+		return -EINVAL;
+	}
+}
+
+/* send packet data request to L1 */
+int l1if_pdch_req(void *obj, uint8_t ts, int is_ptcch, uint32_t fn,
+		  uint16_t arfcn, uint8_t block_nr, uint8_t *data, uint8_t len)
+{
+	struct er_ccu_descr *ccu_descr = obj;
+	struct er_gprs_trau_frame trau_frame;
+	ubit_t trau_frame_encoded[ER_GPRS_TRAU_FRAME_LEN_64K];
+	struct gprs_rlcmac_bts *bts;
+	int rc;
+
+	/* Make sure that the CCU is synchronized and connected. */
+	if (!ccu_descr) {
+		LOGP(DL1IF, LOGL_ERROR, "PCU-DATA-IND: PDCH(ts=%u, arfcn=%u) no CCU context, tossing MAC block...\n",
+		     ts, arfcn);
+		return -EINVAL;
+	}
+	if (!ccu_descr->link.ccu_connected) {
+		LOGPL1IF(ccu_descr, LOGL_NOTICE, "PCU-DATA-IND", "CCU not connected, tossing MAC block...\n");
+		return -EINVAL;
+	}
+	if (!ccu_descr->sync.ccu_synced) {
+		LOGPL1IF(ccu_descr, LOGL_NOTICE, "PCU-DATA-IND", "CCU not synchronized, tossing MAC block...\n");
+		return -EINVAL;
+	}
+
+	/* Hand received MAC block into PCU */
+	bts = gprs_pcu_get_bts_by_nr(the_pcu, ccu_descr->pcu.bts_nr);
+	if (!bts) {
+		LOGPL1IF(ccu_descr, LOGL_NOTICE, "PCU-DATA-IND", "no BTS, tossing MAC block...\n");
+		return -EINVAL;
+	}
+
+	memset(&trau_frame, 0, sizeof(trau_frame));
+	trau_frame.type = ER_GPRS_TRAU_FT_DATA;
+
+	rc = cs_hdr_from_len(len);
+	if (rc < 0) {
+		LOGPL1IF(ccu_descr, LOGL_ERROR, "PCU-DATA-IND",
+			 "unable to encode TRAU frame, invalid CS or MCS value set\n");
+		return -EINVAL;
+	}
+	trau_frame.u.pcu_data_ind.cs_hdr = (enum er_cs_or_hdr)rc;
+	trau_frame.u.pcu_data_ind.tav = ccu_descr->sync.tav;
+	trau_frame.u.pcu_data_ind.ul_frame_err = ccu_descr->sync.ul_frame_err;
+	if (bts->mcs_mask)
+		trau_frame.u.pcu_data_ind.ul_chan_mode = ER_UL_CHMOD_NB_UNKN;
+	else
+		trau_frame.u.pcu_data_ind.ul_chan_mode = ER_UL_CHMOD_NB_GMSK;
+	OSMO_ASSERT(len < sizeof(trau_frame.u.pcu_data_ind.data));
+	memcpy(trau_frame.u.pcu_data_ind.data, data, len);
+
+	/* Regulary ignore one MAC block in uplink. The CCU will then send one CCU-SYNC-IND instead. We use this
+	 * indication to check whether we are still in sync with the CCU. */
+	if (fn % SYNC_CHECK_INTERVAL == 0)
+		trau_frame.u.pcu_data_ind.ul_chan_mode = ER_UL_CHMOD_VOID;
+
+	if (ccu_descr->e1_conn_pars->e1_ts_ss == E1_SUBSLOT_FULL)
+		rc = er_gprs_trau_frame_encode_64k(trau_frame_encoded, &trau_frame);
+	else
+		rc = er_gprs_trau_frame_encode_16k(trau_frame_encoded, &trau_frame);
+	if (rc < 0) {
+		LOGPL1IF(ccu_descr, LOGL_ERROR, "PCU-DATA-IND", "unable to encode TRAU frame\n");
+		return -EINVAL;
+	}
+	LOGPL1IF(ccu_descr, LOGL_DEBUG, "PCU-DATA-IND",
+		 "tav=%u, ul_frame_err=%u, cs_hdr=%u, ul_chan_mode=%u, atten_db=%u, timing_offset=%u,"
+		 " data=%s==>, fn=%u/%u (comp)\n", trau_frame.u.pcu_data_ind.tav,
+		 trau_frame.u.pcu_data_ind.ul_frame_err, trau_frame.u.pcu_data_ind.cs_hdr,
+		 trau_frame.u.pcu_data_ind.ul_chan_mode, trau_frame.u.pcu_data_ind.atten_db,
+		 trau_frame.u.pcu_data_ind.timing_offset, osmo_hexdump_nospc(trau_frame.u.pcu_data_ind.data, len), fn,
+		 fn % 52);
+	er_ccu_if_tx(ccu_descr, trau_frame_encoded, rc);
+
+	/* Make sure timing adjustment value is reset after use */
+	ccu_descr->sync.tav = TIME_ADJ_NONE;
+	ccu_descr->sync.ul_frame_err = false;
+
+	return 0;
+}
+
+void *l1if_open_pdch(uint8_t bts_nr, uint8_t trx_no, uint32_t hlayer1, struct gsmtap_inst *gsmtap)
+{
+	struct er_ccu_descr *ccu_descr;
+
+	/* Note: We do not have enough information to really open anything at
+	 * this point. We will just create the CCU context. */
+
+	ccu_descr = talloc_zero(tall_pcu_ctx, struct er_ccu_descr);
+	OSMO_ASSERT(ccu_descr);
+	ccu_descr->er_ccu_rx_cb = er_ccu_rx_cb;
+	ccu_descr->er_ccu_empty_cb = er_ccu_empty_cb;
+	ccu_descr->pcu.trx_no = trx_no;
+	ccu_descr->pcu.bts_nr = bts_nr;
+
+	return ccu_descr;
+}
+
+int l1if_close_pdch(void *obj)
+{
+	struct er_ccu_descr *ccu_descr = obj;
+
+	if (!ccu_descr) {
+		LOGP(DL1IF, LOGL_ERROR, "PCU-DATA-IND: no CCU context, cannot close unknown PDCH...\n");
+		return -EINVAL;
+	}
+
+	er_ccu_if_close(ccu_descr);
+	talloc_free(ccu_descr);
+	return 0;
+}
+
+int l1if_connect_pdch(void *obj, uint8_t ts)
+{
+	struct er_ccu_descr *ccu_descr = obj;
+	int rc;
+
+	if (!ccu_descr) {
+		LOGP(DL1IF, LOGL_ERROR, "SETUP: PDCH(ts=%u) no CCU context, PDCH never opened before?\n", ts);
+		return -EINVAL;
+	}
+
+	ccu_descr->pcu.ts = ts;
+
+	rc = pcu_l1if_get_e1_ccu_conn_pars(&ccu_descr->e1_conn_pars, ccu_descr->pcu.bts_nr, ccu_descr->pcu.trx_no,
+					   ccu_descr->pcu.ts);
+	if (rc < 0) {
+		LOGPL1IF(ccu_descr, LOGL_ERROR, "SETUP", "cannot find E1 connection parameters for CCU\n");
+		return -EINVAL;
+	}
+
+	rc = er_ccu_if_open(ccu_descr);
+	if (rc < 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+int l1if_disconnect_pdch(void *obj, uint8_t ts)
+{
+	struct er_ccu_descr *ccu_descr = obj;
+
+	if (!ccu_descr) {
+		LOGP(DL1IF, LOGL_ERROR, "SETUP: PDCH(ts=%u) no CCU context, PDCH never opened before?\n", ts);
+		return -EINVAL;
+	}
+
+	er_ccu_if_close(ccu_descr);
+
+	return 0;
+}
+
+int l1if_init(void)
+{
+	er_ccu_if_init(tall_pcu_ctx);
+	return 0;
+}
diff --git a/src/gprs_debug.c b/src/gprs_debug.c
index 03ef083..8aeca5b 100644
--- a/src/gprs_debug.c
+++ b/src/gprs_debug.c
@@ -128,6 +128,13 @@
 		.loglevel = LOGL_NOTICE,
 		.enabled = 1,
 	},
+	[DE1] = {
+		.name = "DE1",
+		.color = "\033[1;31m",
+		.description = "E1 line handling",
+		.loglevel = LOGL_NOTICE,
+		.enabled = 1,
+	},
 };
 
 static int filter_fn(const struct log_context *ctx,
diff --git a/src/gprs_debug.h b/src/gprs_debug.h
index 320c739..db9630c 100644
--- a/src/gprs_debug.h
+++ b/src/gprs_debug.h
@@ -41,6 +41,7 @@
 	DPCU,
 	DNACC,
 	DRIM,
+	DE1,
 	aDebug_LastEntry
 };
 
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 14cc778..6ec806b 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -61,6 +61,23 @@
 
 #define PAGING_GROUP_LEN 3
 
+struct e1_ccu_conn_pars {
+	struct llist_head entry;
+
+	/* Related air interface */
+	uint8_t bts_nr;
+	uint8_t trx_nr;
+	uint8_t ts_nr;
+
+	/* E1 communication parameter */
+	struct e1_conn_pars e1_conn_pars;
+};
+
+/* List storage to collect E1 connection information that we receive through the pcu_sock. The collected data serves as
+ * a lookup table so that we can lookup the E1 connection information for each PDCH (trx number and timeslot number)
+ * when it is needed. */
+static LLIST_HEAD(e1_ccu_table);
+
 /* returns [0,999] on success, > 999 on error */
 uint16_t imsi2paging_group(const char* imsi)
 {
@@ -962,6 +979,73 @@
 	return rc;
 }
 
+/* Query E1 CCU connection parameters by TS and TRX number */
+int pcu_l1if_get_e1_ccu_conn_pars(struct e1_conn_pars **e1_conn_pars, uint8_t bts_nr, uint8_t trx_nr, uint8_t ts_nr)
+{
+	struct e1_ccu_conn_pars *e1_ccu_conn_pars;
+
+	llist_for_each_entry(e1_ccu_conn_pars, &e1_ccu_table, entry) {
+		if (e1_ccu_conn_pars->bts_nr == bts_nr && e1_ccu_conn_pars->trx_nr == trx_nr
+		    && e1_ccu_conn_pars->ts_nr == ts_nr) {
+			*e1_conn_pars = &e1_ccu_conn_pars->e1_conn_pars;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+/* Allocate a new connection parameter struct and store connection parameters */
+static void new_e1_ccu_conn_pars(const struct gsm_pcu_if_e1_ccu_ind *e1_ccu_ind, uint8_t bts_nr)
+{
+	struct e1_ccu_conn_pars *e1_ccu_conn_pars;
+
+	e1_ccu_conn_pars = talloc_zero(tall_pcu_ctx, struct e1_ccu_conn_pars);
+	OSMO_ASSERT(e1_ccu_conn_pars);
+	e1_ccu_conn_pars->bts_nr = bts_nr;
+	e1_ccu_conn_pars->trx_nr = e1_ccu_ind->trx_nr;
+	e1_ccu_conn_pars->ts_nr = e1_ccu_ind->ts_nr;
+	e1_ccu_conn_pars->e1_conn_pars.e1_nr = e1_ccu_ind->e1_nr;
+	e1_ccu_conn_pars->e1_conn_pars.e1_ts = e1_ccu_ind->e1_ts;
+	e1_ccu_conn_pars->e1_conn_pars.e1_ts_ss = e1_ccu_ind->e1_ts_ss;
+	llist_add(&e1_ccu_conn_pars->entry, &e1_ccu_table);
+}
+
+static int pcu_rx_e1_ccu_ind(struct gprs_rlcmac_bts *bts, const struct gsm_pcu_if_e1_ccu_ind *e1_ccu_ind)
+{
+	struct e1_conn_pars *e1_conn_pars;
+	uint8_t rate;
+	uint8_t subslot_nr;
+	int rc;
+
+	/* only used with log statement below, no technical relevance otherwise. */
+	if (e1_ccu_ind->e1_ts_ss > 3) {
+		rate = 64;
+		subslot_nr = 0;
+	} else {
+		rate = 16;
+		subslot_nr = e1_ccu_ind->e1_ts_ss;
+	}
+
+	LOGP(DL1IF, LOGL_NOTICE,
+	     "(ts=%u,trx=%u) new E1 CCU communication parameters for CCU (E1-line:%u, E1-TS:%u, E1-SS:%u, rate:%ukbps)\n",
+	     e1_ccu_ind->ts_nr, e1_ccu_ind->trx_nr, e1_ccu_ind->e1_nr, e1_ccu_ind->e1_ts,
+	     subslot_nr, rate);
+
+	/* Search for an existing entry, when found, update it. */
+	rc = pcu_l1if_get_e1_ccu_conn_pars(&e1_conn_pars, bts->nr, e1_ccu_ind->trx_nr, e1_ccu_ind->ts_nr);
+	if (rc == 0) {
+		e1_conn_pars->e1_nr = e1_ccu_ind->e1_nr;
+		e1_conn_pars->e1_ts = e1_ccu_ind->e1_ts;
+		e1_conn_pars->e1_ts_ss = e1_ccu_ind->e1_ts_ss;
+		return 0;
+	}
+
+	/* Create new connection parameter entry */
+	new_e1_ccu_conn_pars(e1_ccu_ind, bts->nr);
+	return 0;
+}
+
 static int pcu_rx_time_ind(struct gprs_rlcmac_bts *bts, struct gsm_pcu_if_time_ind *time_ind)
 {
 	uint8_t fn13 = time_ind->fn % 13;
@@ -1194,6 +1278,10 @@
 		CHECK_IF_MSG_SIZE(pcu_prim_length, pcu_prim->u.info_ind);
 		rc = pcu_rx_info_ind(bts, &pcu_prim->u.info_ind);
 		break;
+	case PCU_IF_MSG_E1_CCU_IND:
+		CHECK_IF_MSG_SIZE(pcu_prim_length, pcu_prim->u.e1_ccu_ind);
+		rc = pcu_rx_e1_ccu_ind(bts, &pcu_prim->u.e1_ccu_ind);
+		break;
 	case PCU_IF_MSG_TIME_IND:
 		CHECK_IF_MSG_SIZE(pcu_prim_length, pcu_prim->u.time_ind);
 		rc = pcu_rx_time_ind(bts, &pcu_prim->u.time_ind);
diff --git a/src/pcu_l1_if.h b/src/pcu_l1_if.h
index 1827d84..d3d70e4 100644
--- a/src/pcu_l1_if.h
+++ b/src/pcu_l1_if.h
@@ -178,6 +178,17 @@
 void pcu_rx_block_time(struct gprs_rlcmac_bts *bts, uint16_t arfcn, uint32_t fn, uint8_t ts_no);
 uint16_t imsi2paging_group(const char* imsi);
 
+struct e1_conn_pars {
+	/* Number of E1 line */
+	uint8_t e1_nr;
+	/* Number of E1 timeslot */
+	uint8_t e1_ts;
+	/* Number of I.460 subslot inside E1 timeslot */
+	uint8_t e1_ts_ss;
+};
+
+int pcu_l1if_get_e1_ccu_conn_pars(struct e1_conn_pars **e1_conn_pars, uint8_t bts_nr, uint8_t trx_nr, uint8_t ts_nr);
+
 #define PCUIF_HDR_SIZE ( sizeof(struct gsm_pcu_if) - sizeof(((struct gsm_pcu_if *)0)->u) )
 
 #ifdef __cplusplus