diff --git a/app/build.gradle b/app/build.gradle
index df989b41..fde1b81b 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -8,8 +8,8 @@ android {
         applicationId = 'com.tutpro.baresip'
         minSdkVersion 21
         targetSdkVersion 27
-        versionCode = 22
-        versionName = '3.0.1'
+        versionCode = 24
+        versionName = '3.0.3'
         externalNativeBuild {
             cmake {
                 cFlags '-DHAVE_INTTYPES_H'
diff --git a/app/src/main/cpp/baresip.c b/app/src/main/cpp/baresip.c
index 4ba1ca0c..e00276b2 100644
--- a/app/src/main/cpp/baresip.c
+++ b/app/src/main/cpp/baresip.c
@@ -145,6 +145,9 @@ static void ua_event_handler(struct ua *ua, enum ua_event ev,
         case UA_EVENT_MWI_NOTIFY:
             re_snprintf(event_buf, sizeof event_buf, "mwi notify,%s", prm);
             break;
+        case UA_EVENT_AUDIO_ERROR:
+            mem_deref(call);
+            return;
         case UA_EVENT_EXIT:
             re_snprintf(event_buf, sizeof event_buf, "%s", "exit");
             break;
diff --git a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
index 38c95977..e61104b3 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
@@ -457,7 +457,11 @@ class BaresipService: Service() {
         MainActivity.images.clear()
         MainActivity.history.clear()
         MainActivity.messages.clear()
-        unregisterReceiver(nr)
+        try {
+            unregisterReceiver(nr)
+        } catch (e: Exception) {
+            Log.d(LOG_TAG, "Receiver nr has not been registered")
+        }
         nm.cancelAll()
         if (wl.isHeld) wl.release()
         if (fl.isHeld) fl.release()