diff --git a/lapv5.c b/lapv5.c
index 34a5caf..b142544 100644
--- a/lapv5.c
+++ b/lapv5.c
@@ -175,8 +175,8 @@ static void lapv5_sap_free(struct lapv5_sap *sap)
 	talloc_free(sap);
 }
 
-/* General input function for any data received for this LAPV5 instance */
-int lapv5_receive(struct lapv5_instance *li, struct msgb *msg, int *error)
+/* Receive Data (PH-DATA indication) on the given LAPD Instance */
+int lapv5_ph_data_ind(struct lapv5_instance *li, struct msgb *msg, int *error)
 {
 	struct lapd_msg_ctx lctx;
 	struct lapv5_sap *sap;
@@ -271,7 +271,7 @@ int lapv5_receive(struct lapv5_instance *li, struct msgb *msg, int *error)
 }
 
 /* Start a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */
-int lapv5_sap_start(struct lapv5_instance *li, uint16_t dladdr)
+int lapv5_dl_est_req(struct lapv5_instance *li, uint16_t dladdr)
 {
 	struct lapv5_sap *sap;
 	struct osmo_dlsap_prim dp;
@@ -297,7 +297,7 @@ int lapv5_sap_start(struct lapv5_instance *li, uint16_t dladdr)
 }
 
 /* Stop a (user-side) SAP for the specified TEI/SAPI on the LAPD instance */
-int lapv5_sap_stop(struct lapv5_instance *li, uint16_t dladdr)
+int lapv5_dl_rel_req(struct lapv5_instance *li, uint16_t dladdr)
 {
 	struct lapv5_sap *sap;
 	struct osmo_dlsap_prim dp;
@@ -319,7 +319,7 @@ int lapv5_sap_stop(struct lapv5_instance *li, uint16_t dladdr)
 }
 
 /* Transmit Data (DL-DATA request) on the given LAPD Instance / DLADDR */
-void lapv5_transmit(struct lapv5_instance *li, uint8_t dladdr, struct msgb *msg)
+void lapv5_dl_data_req(struct lapv5_instance *li, uint8_t dladdr, struct msgb *msg)
 {
 	struct lapv5_sap *sap;
 	struct osmo_dlsap_prim dp;
@@ -376,7 +376,7 @@ static int send_ph_data_req(struct lapd_msg_ctx *lctx, struct msgb *msg)
 
 	/* forward frame to L1 */
 	LOGDL(dl, LOGL_DEBUG, "TX: %s\n", osmo_hexdump(msg->data, msg->len));
-	li->transmit_cb(msg, li->transmit_cbdata);
+	li->ph_data_req_cb(msg, li->ph_data_req_cbdata);
 
 	return 0;
 }
@@ -407,15 +407,15 @@ static int send_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx)
 		;
 	}
 
-	li->receive_cb(dp, dladdr, li->receive_cbdata);
+	li->dl_receive_cb(dp, dladdr, li->dl_receive_cbdata);
 
 	return 0;
 }
 
 /* Allocate a new LAPV5 instance */
 struct lapv5_instance *lapv5_instance_alloc(int network_side,
-	void (*tx_cb)(struct msgb *msg, void *cbdata), void *tx_cbdata,
-	void (*rx_cb)(struct osmo_dlsap_prim *odp, uint16_t dladdr, void *rx_cbdata), void *rx_cbdata,
+	void (*ph_data_req_cb)(struct msgb *msg, void *cbdata), void *ph_data_req_cbdata,
+	void (*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)
 {
 	struct lapv5_instance *li;
@@ -425,10 +425,10 @@ struct lapv5_instance *lapv5_instance_alloc(int network_side,
 		return NULL;
 
 	li->network_side = network_side;
-	li->transmit_cb = tx_cb;
-	li->transmit_cbdata = tx_cbdata;
-	li->receive_cb = rx_cb;
-	li->receive_cbdata = rx_cbdata;
+	li->ph_data_req_cb = ph_data_req_cb;
+	li->ph_data_req_cbdata = ph_data_req_cbdata;
+	li->dl_receive_cb = dl_receive_cb;
+	li->dl_receive_cbdata = dl_receive_cbdata;
 	li->pcap_fd = -1;
 	li->name = talloc_strdup(li, name);
 	memcpy(&li->profile, profile, sizeof(li->profile));
diff --git a/lapv5.h b/lapv5.h
index 16829cf..da5c057 100644
--- a/lapv5.h
+++ b/lapv5.h
@@ -6,10 +6,10 @@ struct lapv5_instance {
 	struct llist_head list;		/* list of LAPV5 instances */
 	bool network_side;
 
-	void (*transmit_cb)(struct msgb *msg, void *cbdata);
-	void *transmit_cbdata;
-	void (*receive_cb)(struct osmo_dlsap_prim *odp, uint16_t dladdr, void *rx_cbdata);
-	void *receive_cbdata;
+	void (*ph_data_req_cb)(struct msgb *msg, void *cbdata);
+	void *ph_data_req_cbdata;
+	void (*dl_receive_cb)(struct osmo_dlsap_prim *odp, uint16_t dladdr, void *rx_cbdata);
+	void *dl_receive_cbdata;
 
 	struct lapd_profile profile;	/* must be a copy */
 
@@ -19,3 +19,14 @@ struct lapv5_instance {
 };
 
 int lapv5ef_rx(struct v5x_link *link, struct msgb *msg);
+
+int lapv5_dl_est_req(struct lapv5_instance *li, uint16_t dladdr);
+int lapv5_dl_rel_req(struct lapv5_instance *li, uint16_t dladdr);
+void lapv5_dl_data_req(struct lapv5_instance *li, uint8_t dladdr, struct msgb *msg);
+
+int lapv5_ph_data_ind(struct lapv5_instance *li, struct msgb *msg, int *error);
+
+struct lapv5_instance *lapv5_instance_alloc(int network_side,
+	void (*ph_data_req_cb)(struct msgb *msg, void *cbdata), void *ph_data_req_cbdata,
+	void (*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);