diff --git a/doc/timeslot.msc b/doc/timeslot.msc
index 02e7bb3ea..0fd1458e5 100644
--- a/doc/timeslot.msc
+++ b/doc/timeslot.msc
@@ -1,5 +1,5 @@
 msc {
-	bts [label="MS/BTS"], bsc[label="BSC"], bsc_ts[label="BSC timeslot FSM"], bsc_lchan[label="BSC lchan FSM"];
+	bts [label="MS/BTS"], bsc[label="BSC"], bsc_ts[label="BSC timeslot FSM"], bsc_lchan[label="BSC lchan FSM"], pcu_sock[label="PCU socket"];
 
 	bsc_ts abox bsc_ts [label="NOT_INITIALIZED"];
 
@@ -88,6 +88,24 @@ msc {
 	bsc_ts rbox bsc_ts [label="Continue at 'IN_USE' above"];
 	...;
 	...;
+	bts rbox bsc_lchan [label="on PCU disconnect (Ericsson RBS)
+			for all timeslots in state PDCH:" ];
+	bsc_ts abox bsc_ts [label="PDCH"];
+	bsc_ts <- pcu_sock [label="TS_EV_PDCH_DEACT"];
+	bts note bsc_ts [label="PDCH release, see WAIT_PDCH_DEACT above"];
+	...;
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	...;
+	...;
+	bts rbox bsc_lchan [label="on PCU reconnect (Ericsson RBS)
+			for all timeslots in state UNUSED:" ];
+	bsc_ts abox bsc_ts [label="UNUSED"];
+	bsc_ts <- pcu_sock [label="TS_EV_PDCH_ACT"];
+	bts note bsc_ts [label="PDCH activation, see WAIT_PDCH_ACT above"];
+	...;
+	bsc_ts abox bsc_ts [label="PDCH"];
+	...;
+	...;
 
 	bts rbox bsc_lchan [label="on erratic event"];
 	bsc_ts -> bsc_lchan [label="LCHAN_EV_TS_ERROR"];
diff --git a/include/osmocom/bsc/pcu_if.h b/include/osmocom/bsc/pcu_if.h
index 3c34cdf4c..2a2afa869 100644
--- a/include/osmocom/bsc/pcu_if.h
+++ b/include/osmocom/bsc/pcu_if.h
@@ -14,6 +14,9 @@ struct pcu_sock_state {
 	struct llist_head upqueue;	/* queue for sending messages */
 };
 
+/* Check if BTS has a PCU connection */
+bool pcu_connected(struct gsm_bts *bts);
+
 /* PCU relevant information has changed; Inform PCU (if connected) */
 void pcu_info_update(struct gsm_bts *bts);
 
diff --git a/include/osmocom/bsc/timeslot_fsm.h b/include/osmocom/bsc/timeslot_fsm.h
index cea1e4c4d..c1b61b812 100644
--- a/include/osmocom/bsc/timeslot_fsm.h
+++ b/include/osmocom/bsc/timeslot_fsm.h
@@ -36,10 +36,18 @@ enum ts_fsm_event {
 	TS_EV_RSL_DOWN,
 	TS_EV_LCHAN_REQUESTED,
 	TS_EV_LCHAN_UNUSED,
+
+	/* RSL responses received from the BTS: */
 	TS_EV_PDCH_ACT_ACK,
 	TS_EV_PDCH_ACT_NACK,
 	TS_EV_PDCH_DEACT_ACK,
 	TS_EV_PDCH_DEACT_NACK,
+
+	/* BSC co-located PCU disconnects from PCU socket, deactivate PDCH */
+	TS_EV_PDCH_DEACT,
+
+	/* BSC co-located PCU (re)connects to PCU socket, activate PDCH */
+	TS_EV_PDCH_ACT,
 };
 
 void ts_fsm_alloc(struct gsm_bts_trx_ts *ts);
@@ -52,3 +60,6 @@ bool ts_is_pchan_switching(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config
 bool ts_usable_as_pchan(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config as_pchan, bool allow_pchan_switch);
 
 void ts_set_pchan_is(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config pchan_is);
+
+void ts_pdch_act(struct gsm_bts_trx_ts *ts);
+void ts_pdch_deact(struct gsm_bts_trx_ts *ts);
diff --git a/src/osmo-bsc/pcu_sock.c b/src/osmo-bsc/pcu_sock.c
index 1d5e56c3f..51b59c6ef 100644
--- a/src/osmo-bsc/pcu_sock.c
+++ b/src/osmo-bsc/pcu_sock.c
@@ -44,6 +44,7 @@
 #include <osmocom/bsc/gsm_04_08_rr.h>
 #include <osmocom/bsc/bts.h>
 #include <osmocom/bsc/bts_sm.h>
+#include <osmocom/bsc/timeslot_fsm.h>
 
 static int pcu_sock_send(struct gsm_bts *bts, struct msgb *msg);
 
@@ -58,11 +59,14 @@ static const char *sapi_string[] = {
 	[PCU_IF_SAPI_PCH_DT] =	"PCH_DT",
 };
 
-/* Check if BTS has a PCU connection */
-static bool pcu_connected(struct gsm_bts *bts)
+bool pcu_connected(struct gsm_bts *bts)
 {
 	struct pcu_sock_state *state = bts->pcu_state;
 
+	/* BSC co-located PCU is only supported for Ericsson RBS */
+	if (!is_ericsson_bts(bts))
+		return false;
+
 	if (!state)
 		return false;
 	if (state->conn_bfd.fd <= 0)
@@ -751,8 +755,7 @@ static void pcu_sock_close(struct pcu_sock_state *state)
 	struct osmo_fd *bfd = &state->conn_bfd;
 	struct gsm_bts *bts;
 	struct gsm_bts_trx *trx;
-	struct gsm_bts_trx_ts *ts;
-	int i, j;
+	int j;
 
 	/* FIXME: allow multiple BTS */
 	bts = llist_entry(state->net->bts_list.next, struct gsm_bts, list);
@@ -773,15 +776,14 @@ static void pcu_sock_close(struct pcu_sock_state *state)
 #endif
 
 	/* release PDCH */
-	for (i = 0; i < 8; i++) {
-		trx = gsm_bts_trx_num(bts, i);
-		if (!trx)
-			break;
-		for (j = 0; j < 8; j++) {
-			ts = &trx->ts[j];
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		for (j = 0; j < ARRAY_SIZE(trx->ts); j++) {
+			struct gsm_bts_trx_ts *ts = &trx->ts[j];
+			/* BSC co-located PCU applies only to Ericsson RBS, which supports only GSM_PCHAN_OSMO_DYN.
+			 * So we need to deact only on this pchan kind. */
 			if (ts->mo.nm_state.operational == NM_OPSTATE_ENABLED
-			    && ts->pchan_is == GSM_PCHAN_PDCH) {
-				printf("l1sap_chan_rel(trx,gsm_lchan2chan_nr(ts->lchan));\n");
+			    && ts->pchan_on_init == GSM_PCHAN_OSMO_DYN) {
+				ts_pdch_deact(ts);
 			}
 		}
 	}
@@ -908,9 +910,15 @@ static int pcu_sock_accept(struct osmo_fd *bfd, unsigned int flags)
 	struct pcu_sock_state *state = (struct pcu_sock_state *)bfd->data;
 	struct osmo_fd *conn_bfd = &state->conn_bfd;
 	struct sockaddr_un un_addr;
+	struct gsm_bts *bts;
+	struct gsm_bts_trx *trx;
+	int j;
 	socklen_t len;
 	int rc;
 
+	/* FIXME: allow multiple BTS */
+	bts = llist_entry(state->net->bts_list.next, struct gsm_bts, list);
+
 	len = sizeof(un_addr);
 	rc = accept(bfd->fd, (struct sockaddr *) &un_addr, &len);
 	if (rc < 0) {
@@ -939,6 +947,18 @@ static int pcu_sock_accept(struct osmo_fd *bfd, unsigned int flags)
 
 	LOGP(DPCU, LOGL_NOTICE, "PCU socket connected to external PCU\n");
 
+	/* activate PDCH */
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		for (j = 0; j < ARRAY_SIZE(trx->ts); j++) {
+			struct gsm_bts_trx_ts *ts = &trx->ts[j];
+			/* (See comment in pcu_sock_close above) */
+			if (ts->mo.nm_state.operational == NM_OPSTATE_ENABLED
+			    && ts->pchan_on_init == GSM_PCHAN_OSMO_DYN) {
+				ts_pdch_act(ts);
+			}
+		}
+	}
+
 	return 0;
 }
 
diff --git a/src/osmo-bsc/timeslot_fsm.c b/src/osmo-bsc/timeslot_fsm.c
index 28e2aaa70..16d736033 100644
--- a/src/osmo-bsc/timeslot_fsm.c
+++ b/src/osmo-bsc/timeslot_fsm.c
@@ -341,6 +341,11 @@ static void ts_fsm_unused_pdch_act(struct osmo_fsm_inst *fi)
 		return;
 	}
 
+	if (!pcu_connected(bts)) {
+		LOG_TS(ts, LOGL_DEBUG, "PCU not connected: not activating PDCH.\n");
+		return;
+	}
+
 	osmo_fsm_inst_state_chg(fi, TS_ST_WAIT_PDCH_ACT, CHAN_ACT_DEACT_TIMEOUT,
 				T_CHAN_ACT_DEACT);
 }
@@ -408,6 +413,10 @@ static void ts_fsm_unused(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 		/* ignored. */
 		return;
 
+	case TS_EV_PDCH_ACT:
+		ts_fsm_unused_pdch_act(fi);
+		return;
+
 	default:
 		OSMO_ASSERT(false);
 	}
@@ -531,6 +540,10 @@ static void ts_fsm_pdch(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 			}
 		}
 
+	case TS_EV_PDCH_DEACT:
+		ts_fsm_pdch_deact(fi);
+		return;
+
 	case TS_EV_LCHAN_UNUSED:
 		/* ignored */
 		return;
@@ -889,6 +902,7 @@ static const struct osmo_fsm_state ts_fsm_states[] = {
 		.in_event_mask = 0
 			| S(TS_EV_LCHAN_REQUESTED)
 			| S(TS_EV_LCHAN_UNUSED)
+			| S(TS_EV_PDCH_ACT)
 			,
 		.out_state_mask = 0
 			| S(TS_ST_WAIT_PDCH_ACT)
@@ -921,6 +935,7 @@ static const struct osmo_fsm_state ts_fsm_states[] = {
 		.in_event_mask = 0
 			| S(TS_EV_LCHAN_REQUESTED)
 			| S(TS_EV_LCHAN_UNUSED)
+			| S(TS_EV_PDCH_DEACT)
 			,
 		.out_state_mask = 0
 			| S(TS_ST_WAIT_PDCH_DEACT)
@@ -992,6 +1007,8 @@ static const struct value_string ts_fsm_event_names[] = {
 	OSMO_VALUE_STRING(TS_EV_PDCH_ACT_NACK),
 	OSMO_VALUE_STRING(TS_EV_PDCH_DEACT_ACK),
 	OSMO_VALUE_STRING(TS_EV_PDCH_DEACT_NACK),
+	OSMO_VALUE_STRING(TS_EV_PDCH_DEACT),
+	OSMO_VALUE_STRING(TS_EV_PDCH_ACT),
 	{}
 };
 
@@ -1105,3 +1122,23 @@ bool ts_usable_as_pchan(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config as_
 
 	return true;
 }
+
+void ts_pdch_act(struct gsm_bts_trx_ts *ts)
+{
+	/* We send the activation event only when the timeslot is UNUSED. In all other cases the timeslot FSM
+	 * will automatically handle the activation at some later point. */
+	if (ts->fi->state != TS_ST_UNUSED)
+		return;
+
+	osmo_fsm_inst_dispatch(ts->fi, TS_EV_PDCH_ACT, NULL);
+}
+
+void ts_pdch_deact(struct gsm_bts_trx_ts *ts)
+{
+	/* We send the deactivation event only when the timeslot is active as PDCH. The timeslot FSM will check
+	 * if the PCU is available before activating the PDCH again. */
+	if (ts->fi->state != TS_ST_PDCH)
+		return;
+
+	osmo_fsm_inst_dispatch(ts->fi, TS_EV_PDCH_DEACT, NULL);
+}