diff --git a/src/pstn/pstn.c b/src/pstn/pstn.c
index 66389da..d3ea313 100644
--- a/src/pstn/pstn.c
+++ b/src/pstn/pstn.c
@@ -1411,17 +1411,34 @@ static void swap_active_hold(pstn_t *pstn)
 /* process hookflash from various events: short hangup, off-hook-pulse, pulse digit 1 ... */
 static void hookflash(pstn_t *pstn)
 {
+	/* hookflash: no connected call, no call on hold */
+	if (pstn->call[PSTN_CALL_ACTIVE]->state != CALL_STATE_ACTIVE
+	 && !pstn->call[PSTN_CALL_HOLD]->cc_callref) {
+		PDEBUG(DTEL, DEBUG_INFO, "There is an active call that is not connected, but no call on hold, ignoring hookflash.\n");
+		return;
+	}
+
+	/* stop timer */
+	timer_off(pstn);
 	/* stop tone (CW tone) */
 	tone_off(pstn);
 	/* clear dialing */
 	pstn->dialing[0] = '\0';
+	/* release incomplete call, if any */
+	if (pstn->call[PSTN_CALL_ACTIVE]->state != CALL_STATE_ACTIVE) {
+		PDEBUG(DTEL, DEBUG_INFO, "There is an active call that is not connected, release it.\n");
+		/* release active call that is not connectd */
+		release_call(pstn, PSTN_CALL_ACTIVE, OSMO_CC_ISDN_CAUSE_NORM_CALL_CLEAR);
+	}
 	/* if call on hold, swap calls */
 	if (pstn->call[PSTN_CALL_HOLD]->cc_callref) {
 		PDEBUG(DTEL, DEBUG_INFO, "There is a call on hold, so swap both calls.\n");
 		/* swap ACTIVE call and call on HOLD */
 		swap_active_hold(pstn);
-		/* send notify to call on hold */
-		notify_ind(pstn->call[PSTN_CALL_HOLD], OSMO_CC_NOTIFY_REMOTE_HOLD);
+		if (pstn->call[PSTN_CALL_HOLD]->cc_callref) {
+			/* send notify to call on hold */
+			notify_ind(pstn->call[PSTN_CALL_HOLD], OSMO_CC_NOTIFY_REMOTE_HOLD);
+		}
 		/* if waiting call, answer it */
 		if (pstn->call[PSTN_CALL_ACTIVE]->state != CALL_STATE_ACTIVE
 		 && pstn->call[PSTN_CALL_ACTIVE]->state != CALL_STATE_HOLD) {
@@ -1430,7 +1447,8 @@ static void hookflash(pstn_t *pstn)
 		}
 		/* change state */
 		pstn_call_state(pstn->call[PSTN_CALL_ACTIVE], CALL_STATE_ACTIVE);
-		pstn_call_state(pstn->call[PSTN_CALL_HOLD], CALL_STATE_HOLD);
+		if (pstn->call[PSTN_CALL_HOLD]->cc_callref)
+			pstn_call_state(pstn->call[PSTN_CALL_HOLD], CALL_STATE_HOLD);
 		/* send notify to active call */
 		notify_ind(pstn->call[PSTN_CALL_ACTIVE], OSMO_CC_NOTIFY_REMOTE_RETRIEVAL);
 		return;