diff --git a/libs/freetdm/src/ftdm_state.c b/libs/freetdm/src/ftdm_state.c
index 54ecde530d..d3f99f6074 100644
--- a/libs/freetdm/src/ftdm_state.c
+++ b/libs/freetdm/src/ftdm_state.c
@@ -370,12 +370,19 @@ end:
 	}
 	ftdm_set_flag(ftdmchan, FTDM_CHANNEL_STATE_CHANGE);
 
-	ftdm_mutex_lock(ftdmchan->span->mutex);
-	ftdm_set_flag(ftdmchan->span, FTDM_SPAN_STATE_CHANGE);
 	if (ftdmchan->span->pendingchans) {
 		ftdm_queue_enqueue(ftdmchan->span->pendingchans, ftdmchan);
+	} else {
+		/* there is a potential deadlock here, if a signaling module is processing
+		 * state changes while the ftdm_span_stop() function is called, the signaling
+		 * thread will block until it can acquire the span lock, but the thread calling
+		 * ftdm_span_stop() which holds the span lock is waiting on the signaling thread
+		 * to finish ... The only reason to acquire the span lock is this flag, new
+		 * signaling modules should use the pendingchans queue instead of this flag,
+		 * as of today a few modules need still to be updated before we can get rid of
+		 * this flag (ie, ftmod_libpri, ftmod_isdn, ftmod_analog) */
+		ftdm_set_flag_locked(ftdmchan->span, FTDM_SPAN_STATE_CHANGE);
 	}
-	ftdm_mutex_unlock(ftdmchan->span->mutex);
 
 	if (ftdm_test_flag(ftdmchan, FTDM_CHANNEL_NONBLOCK)) {
 		/* the channel should not block waiting for state processing */
diff --git a/libs/freetdm/src/include/private/ftdm_types.h b/libs/freetdm/src/include/private/ftdm_types.h
index 2ed9fd04c5..6df25fe4d2 100755
--- a/libs/freetdm/src/include/private/ftdm_types.h
+++ b/libs/freetdm/src/include/private/ftdm_types.h
@@ -173,6 +173,12 @@ typedef enum {
 	FTDM_SPAN_SUSPENDED = (1 << 3),
 	FTDM_SPAN_IN_THREAD = (1 << 4),
 	FTDM_SPAN_STOP_THREAD = (1 << 5),
+	/*! Signaling modules set this flag to use fchan->pendingchans queue instead
+	 *  of the FTDM_SPAN_STATE_CHANGE flag to detect when there is channels with
+	 *  a state change pending in the span. If you set this member you can't rely
+	 *  on FTDM_SPAN_STATE_CHANGE anymore and must use the queue only instead. This
+	 *  is the new way of detecting state changes, new modules should always set this
+	 *  flag, the old modules still relying on FTDM_SPAN_STATE_CHANGE should be updated */
 	FTDM_SPAN_USE_CHAN_QUEUE = (1 << 6),
 	FTDM_SPAN_SUGGEST_CHAN_ID = (1 << 7),
 	FTDM_SPAN_USE_AV_RATE = (1 << 8),