diff --git a/src/lapv5.c b/src/lapv5.c
index e95ff6b..5e54c59 100644
--- a/src/lapv5.c
+++ b/src/lapv5.c
@@ -35,7 +35,9 @@
 
 #include "v5x_internal.h"
 #include "v5x_protocol.h"
+#include "v5x_le_port_fsm.h"
 #include "lapv5.h"
+#include "layer1.h"
 #include "logging.h"
 
 #define LAPD_ADDR1(sapi, cr) ((((sapi) & 0x3f) << 2) | (((cr) & 0x1) << 1))
@@ -132,7 +134,7 @@ static struct lapv5_sap *lapv5_sap_alloc(struct lapv5_instance *li, uint16_t v5d
 	if (!sap)
 		return NULL;
 
-	LOGP(DLLAPD, LOGL_NOTICE, "(%s): LAPV5 Allocating SAP for V5_DLADDR=%u (dl=%p, sap=%p)\n",
+	LOGP(DLLAPD, LOGL_DEBUG, "(%s): LAPV5 Allocating SAP for V5_DLADDR=%u (dl=%p, sap=%p)\n",
 	     name, v5dladdr, &sap->dl, sap);
 
 	sap->li = li;
@@ -141,7 +143,7 @@ static struct lapv5_sap *lapv5_sap_alloc(struct lapv5_instance *li, uint16_t v5d
 	profile = &li->profile;
 
 	k = profile->k[0];
-	LOGP(DLLAPD, LOGL_NOTICE, "(%s): k=%d N200=%d N201=%d T200=%d.%d T203=%d.%d\n",
+	LOGP(DLLAPD, LOGL_DEBUG, "(%s): k=%d N200=%d N201=%d T200=%d.%d T203=%d.%d\n",
 		name, k, profile->n200, profile->n201, profile->t200_sec,
 		profile->t200_usec, profile->t203_sec, profile->t203_usec);
 	lapd_dl_init2(dl, k, 128, profile->n201, name);
@@ -167,7 +169,7 @@ static struct lapv5_sap *lapv5_sap_alloc(struct lapv5_instance *li, uint16_t v5d
 /* Free SAP instance, including the datalink */
 static void lapv5_sap_free(struct lapv5_sap *sap)
 {
-	LOGSAP(sap, LOGL_NOTICE, "LAPV5 Freeing SAP for DLADDR=%u (dl=%p, sap=%p)\n", sap->dladdr, &sap->dl, sap);
+	LOGSAP(sap, LOGL_DEBUG, "LAPV5 Freeing SAP for DLADDR=%u (dl=%p, sap=%p)\n", sap->dladdr, &sap->dl, sap);
 
 	/* free datalink structures and timers */
 	lapd_dl_exit(&sap->dl);
@@ -269,7 +271,7 @@ int lapv5_ph_data_ind(struct lapv5_instance *li, struct msgb *msg, int *error)
 	return lapd_ph_data_ind(msg, &lctx);
 }
 
-/* Start a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */
+/* Start a (LE-side) SAP for the specified TEI/SAPI on the LAPD instance */
 int lapv5_dl_est_req(struct lapv5_instance *li, uint16_t dladdr)
 {
 	struct lapv5_sap *sap;
@@ -284,18 +286,19 @@ int lapv5_dl_est_req(struct lapv5_instance *li, uint16_t dladdr)
 	if (!sap)
 		return -ENOMEM;
 
-	LOGSAP(sap, LOGL_NOTICE, "LAPV5 DL-ESTABLISH request DLADDR=%u\n", dladdr);
+	LOGSAP(sap, LOGL_DEBUG, "LAPV5 DL-ESTABLISH request DLADDR=%u\n", dladdr);
 
 	/* prepare prim */
 	msg = msgb_alloc_headroom(DLSAP_MSGB_SIZE, DLSAP_MSGB_HEADROOM, "DL EST");
 	msg->l3h = msg->data;
+	memset(&dp, 0, sizeof(dp));
         osmo_prim_init(&dp.oph, 0, PRIM_DL_EST, PRIM_OP_REQUEST, msg);
 
         /* send to L2 */
         return lapd_recv_dlsap(&dp, &sap->dl.lctx);
 }
 
-/* Stop a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */
+/* Stop a (LE-side) SAP for the specified TEI/SAPI on the LAPD instance */
 int lapv5_dl_rel_req(struct lapv5_instance *li, uint16_t dladdr)
 {
 	struct lapv5_sap *sap;
@@ -306,11 +309,12 @@ int lapv5_dl_rel_req(struct lapv5_instance *li, uint16_t dladdr)
 	if (!sap)
 		return -ENODEV;
 
-	LOGSAP(sap, LOGL_NOTICE, "LAPV5 DL-RELEASE request DLADDR=%u\n", dladdr);
+	LOGSAP(sap, LOGL_DEBUG, "LAPV5 DL-RELEASE request DLADDR=%u\n", dladdr);
 
 	/* prepare prim */
 	msg = msgb_alloc_headroom(DLSAP_MSGB_SIZE, DLSAP_MSGB_HEADROOM, "DL REL");
 	msg->l3h = msg->data;
+	memset(&dp, 0, sizeof(dp));
         osmo_prim_init(&dp.oph, 0, PRIM_DL_REL, PRIM_OP_REQUEST, msg);
 
         /* send to L2 */
@@ -325,13 +329,14 @@ int lapv5_dl_data_req(struct lapv5_instance *li, uint16_t dladdr, struct msgb *m
 
 	sap = lapv5_sap_find(li, dladdr);
 	if (!sap) {
-		LOGLI(li, LOGL_INFO, "LAPV5 Tx on unknown DLADDR=%u\n", dladdr);
+		LOGLI(li, LOGL_NOTICE, "LAPV5 Tx on unknown DLADDR=%u\n", dladdr);
 		msgb_free(msg);
 		return -EINVAL;
 	}
 
 	/* prepare prim */
 	msg->l3h = msg->data;
+	memset(&dp, 0, sizeof(dp));
 	osmo_prim_init(&dp.oph, 0, PRIM_DL_DATA, PRIM_OP_REQUEST, msg);
 
 	/* send to L2 */
@@ -395,10 +400,10 @@ static int send_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx)
 
 	switch (dp->oph.primitive) {
 	case PRIM_DL_EST:
-		LOGDL(dl, LOGL_NOTICE, "LAPD DL-ESTABLISH %s DLADDR=%u\n", op, dladdr);
+		LOGDL(dl, LOGL_DEBUG, "LAPD DL-ESTABLISH %s DLADDR=%u\n", op, dladdr);
 		break;
 	case PRIM_DL_REL:
-		LOGDL(dl, LOGL_NOTICE, "LAPD DL-RELEASE %s DLADDR=%u\n", op, dladdr);
+		LOGDL(dl, LOGL_DEBUG, "LAPD DL-RELEASE %s DLADDR=%u\n", op, dladdr);
 		lapv5_sap_free(sap);
 		/* note: sap and dl is now gone, don't use it anymore */
 		break;
@@ -499,27 +504,25 @@ int lapv5ef_rx(struct v5x_link *link, struct msgb *msg)
 	case V5X_DLADDR_PSTN:
 		/* hand-over to LAPD-DL instance for PSTN */
 		li = link->interface->pstn.li;
-		/* TODO */
 		break;
 	case V5X_DLADDR_CTRL:
 		/* hand-over to LAPD-DL instance for CTRL */
-		/* TODO */
 		li = link->interface->control.li;
 		break;
 	case V52_DLADDR_BCC:
+		/* hand-over to LAPD-DL instance for BCC */
 		li = link->interface->bcc.li;
-		/* TOOD: implement V5.2 */
-		msgb_free(msg);
 		break;
 	case V52_DLADDR_PROTECTION:
-		li = link->interface->protection[0].li;
-		/* TOOD: implement V5.2 */
-		msgb_free(msg);
+		/* hand-over to LAPD-DL instance for PROTECTION */
+		if (link == link->interface->primary_link)
+			li = link->interface->protection.li[0];
+		if (link == link->interface->secondary_link)
+			li = link->interface->protection.li[1];
 		break;
 	case V52_DLADDR_LCP:
+		/* hand-over to LAPD-DL instance for LCP */
 		li = link->interface->lcp.li;
-		/* TOOD: implement V5.2 */
-		msgb_free(msg);
 		break;
 	default:
 		if (efaddr >= 8176) {
@@ -535,6 +538,11 @@ int lapv5ef_rx(struct v5x_link *link, struct msgb *msg)
 			msgb_free(msg);
 			return -EINVAL;
 		}
+		if (!v5x_le_port_isdn_is_operational(v5up->port_fi)) {
+			LOGP(DV5EF, LOGL_NOTICE, "Dropping D-channel (AN->LE) message of non-operational ISDN port for EFaddr %d.\n", efaddr);
+			msgb_free(msg);
+			return -EIO;
+		}
 		LOGP(DV5EF, LOGL_DEBUG, "Recevied frame for EFaddr %d: %s\n", efaddr, osmo_hexdump(msg->data, msg->len));
 		ph_socket_tx_msg(&v5up->ph_socket, 3, PH_PRIM_DATA_IND, msg->data, msg->len);
 		msgb_free(msg);
@@ -556,13 +564,18 @@ int lapv5ef_tx(struct v5x_user_port *v5up, struct msgb *msg)
 {
 	uint16_t efaddr = v5up->nr, efaddr_enc;
 
+	if (!v5x_le_port_isdn_is_operational(v5up->port_fi)) {
+		LOGP(DV5EF, LOGL_NOTICE, "Dropping D-channel (LE->AN) message of non-operational ISDN port for EFaddr %d.\n", efaddr);
+		msgb_free(msg);
+		return -EIO;
+	}
 	/* relay function for LAPD of user ports */
 	LOGP(DV5EF, LOGL_DEBUG, "Sending frame for EFaddr %d: %s\n", efaddr, osmo_hexdump(msg->data, msg->len));
 	msg->l2h = msgb_push(msg, 2);
 	efaddr_enc = v5x_l3_addr_enc(efaddr, 1);
 	msg->l2h[0] = efaddr_enc >> 8;
 	msg->l2h[1] = efaddr_enc;
-	ph_data_req_hack(msg, NULL);
+	ph_data_req_hdlc(msg, v5up->interface);
 
 	return 0;
 }
diff --git a/src/lapv5.h b/src/lapv5.h
index 48a6cbd..e512e04 100644
--- a/src/lapv5.h
+++ b/src/lapv5.h
@@ -32,6 +32,8 @@ struct lapv5_instance *lapv5_instance_alloc(int network_side,
 	int (*ph_data_req_cb)(struct msgb *msg, void *cbdata), void *ph_data_req_cbdata,
 	int (*dl_receive_cb)(struct osmo_dlsap_prim *odp, uint16_t dladdr, void *rx_cbdata), void *dl_receive_cbdata,
 	const struct lapd_profile *profile, const char *name);
+void lapv5_instance_set_profile(struct lapv5_instance *li, const struct lapd_profile *profile);
+void lapv5_instance_free(struct lapv5_instance *li);
 
 int lapv5ef_rx(struct v5x_link *link, struct msgb *msg);
 int lapv5ef_tx(struct v5x_user_port *v5up, struct msgb *msg);