diff --git a/app/src/main/java/com/nynja/mobile/communicator/data/sdk/calls/ConferenceSDKModule.java b/app/src/main/java/com/nynja/mobile/communicator/data/sdk/calls/ConferenceSDKModule.java
index c7eacc2658160776cddbd9d6adfd8a2cc93cfd3b..05fe2941ca70772f786bfcae1c152b0a24f1617f 100644
--- a/app/src/main/java/com/nynja/mobile/communicator/data/sdk/calls/ConferenceSDKModule.java
+++ b/app/src/main/java/com/nynja/mobile/communicator/data/sdk/calls/ConferenceSDKModule.java
@@ -3954,6 +3954,9 @@ public class ConferenceSDKModule extends BaseSDKModule {
     public boolean onMediaButtonsLocalEvent(Context context, LocalEvent event) {
         if (event instanceof HeadphoneState) {
             HeadphoneState hs = (HeadphoneState)event;
+            Timber.d("ConferenceSDKModule::onMediaButtonsLocalEvent(): " +
+                    "local event headphoneState=%s", hs.getState().toString());
+
             switch (hs.getState()) {
                 case Connected:
                     switchToBTDevice();
diff --git a/app/src/main/java/com/nynja/mobile/communicator/utils/NotificationHelper.java b/app/src/main/java/com/nynja/mobile/communicator/utils/NotificationHelper.java
index 5891213277a555bad8238c8619a02331147446d8..3f918e6b1bad3c57f87340b8a679dfa69de76fae 100644
--- a/app/src/main/java/com/nynja/mobile/communicator/utils/NotificationHelper.java
+++ b/app/src/main/java/com/nynja/mobile/communicator/utils/NotificationHelper.java
@@ -98,6 +98,7 @@ public class NotificationHelper extends ContextWrapper {
         mNynjaSoundManager = soundManager;
     }
 
+    @TargetApi(Build.VERSION_CODES.O)
     public void setupNotifications(SettingNotifications settingNotifications, boolean force) {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return;
         if (force) {
@@ -115,6 +116,7 @@ public class NotificationHelper extends ContextWrapper {
         initChannels(settingNotifications);
     }
 
+    @TargetApi(Build.VERSION_CODES.O)
     private void onUpgrade(SettingNotifications settingNotifications,
                            long oldVersion, long newVersion) {
         if (oldVersion == 0) {
@@ -279,7 +281,8 @@ public class NotificationHelper extends ContextWrapper {
         return channel;
     }
 
-    public void updateRingerSoundAndCreateChannel(SettingNotifications settingNotifications) {
+    @TargetApi(Build.VERSION_CODES.O)
+    private void updateRingerSoundAndCreateChannel(SettingNotifications settingNotifications) {
             Timber.d("updateRingerSoundAndCreateChannel()");
             deleteRingingChannel(settingNotifications);
             settingNotifications.setRingerSoundIndex(settingNotifications.getRingerSoundIndex() + 1);
@@ -294,7 +297,9 @@ public class NotificationHelper extends ContextWrapper {
             Timber.d("ringerSoundChange(): check 2: channel old_id=%d",
                     settingNotifications.getRingerSoundIndex());
             settingNotifications.setRingerSound(ringerSound);
-            updateRingerSoundAndCreateChannel(settingNotifications);
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                updateRingerSoundAndCreateChannel(settingNotifications);
+            }
             return true;
         }
         return false;