diff --git a/app/src/main/java/org/linphone/ui/main/MainActivity.kt b/app/src/main/java/org/linphone/ui/main/MainActivity.kt
index 2d51f5d76..35d63aae0 100644
--- a/app/src/main/java/org/linphone/ui/main/MainActivity.kt
+++ b/app/src/main/java/org/linphone/ui/main/MainActivity.kt
@@ -29,6 +29,7 @@ import androidx.annotation.DrawableRes
 import androidx.annotation.UiThread
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.WindowCompat
+import androidx.core.view.children
 import androidx.databinding.DataBindingUtil
 import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.lifecycleScope
@@ -43,6 +44,7 @@ import org.linphone.R
 import org.linphone.databinding.MainActivityBinding
 import org.linphone.ui.main.viewmodel.MainViewModel
 import org.linphone.utils.AppUtils
+import org.linphone.utils.slideInToastFromTop
 import org.linphone.utils.slideInToastFromTopForDuration
 
 @UiThread
@@ -97,6 +99,21 @@ class MainActivity : AppCompatActivity() {
                 coreContext.showCallActivity()
             }
         }
+
+        viewModel.defaultAccountRegistrationErrorEvent.observe(this) {
+            it.consume { error ->
+                val tag = "DEFAULT_ACCOUNT_REGISTRATION_ERROR"
+                if (error) {
+                    // First remove any already existing connection error toat
+                    removePersistentRedToast(tag)
+
+                    val message = getString(R.string.toast_default_account_connection_state_error)
+                    showPersistentRedToast(message, R.drawable.warning_circle, tag)
+                } else {
+                    removePersistentRedToast(tag)
+                }
+            }
+        }
     }
 
     override fun onPostCreate(savedInstanceState: Bundle?) {
@@ -151,6 +168,30 @@ class MainActivity : AppCompatActivity() {
         )
     }
 
+    private fun showPersistentRedToast(
+        message: String,
+        @DrawableRes icon: Int,
+        tag: String,
+        doNotTint: Boolean = false
+    ) {
+        val redToast = AppUtils.getRedToast(this, binding.toastsArea, message, icon, doNotTint)
+        redToast.root.tag = tag
+        binding.toastsArea.addView(redToast.root)
+
+        redToast.root.slideInToastFromTop(
+            binding.toastsArea as ViewGroup,
+            true
+        )
+    }
+
+    fun removePersistentRedToast(tag: String) {
+        for (child in binding.toastsArea.children) {
+            if (child.tag == tag) {
+                binding.toastsArea.removeView(child)
+            }
+        }
+    }
+
     private fun loadContacts() {
         coreContext.contactsManager.loadContacts(this)
 
diff --git a/app/src/main/java/org/linphone/ui/main/viewmodel/MainViewModel.kt b/app/src/main/java/org/linphone/ui/main/viewmodel/MainViewModel.kt
index 69ce2bb24..b5784fe84 100644
--- a/app/src/main/java/org/linphone/ui/main/viewmodel/MainViewModel.kt
+++ b/app/src/main/java/org/linphone/ui/main/viewmodel/MainViewModel.kt
@@ -25,9 +25,11 @@ import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import org.linphone.LinphoneApplication.Companion.coreContext
 import org.linphone.R
+import org.linphone.core.Account
 import org.linphone.core.Call
 import org.linphone.core.Core
 import org.linphone.core.CoreListenerStub
+import org.linphone.core.RegistrationState
 import org.linphone.core.tools.Log
 import org.linphone.utils.AppUtils
 import org.linphone.utils.Event
@@ -44,6 +46,10 @@ class MainViewModel @UiThread constructor() : ViewModel() {
 
     val callsStatus = MutableLiveData<String>()
 
+    val defaultAccountRegistrationErrorEvent: MutableLiveData<Event<Boolean>> by lazy {
+        MutableLiveData<Event<Boolean>>()
+    }
+
     val changeSystemTopBarColorToInCallEvent: MutableLiveData<Event<Boolean>> by lazy {
         MutableLiveData<Event<Boolean>>()
     }
@@ -52,6 +58,8 @@ class MainViewModel @UiThread constructor() : ViewModel() {
         MutableLiveData<Event<Boolean>>()
     }
 
+    var defaultAccountRegistrationFailed = false
+
     private val coreListener = object : CoreListenerStub() {
         @WorkerThread
         override fun onLastCallEnded(core: Core) {
@@ -71,9 +79,41 @@ class MainViewModel @UiThread constructor() : ViewModel() {
             }
             atLastOneCall.postValue(core.callsNb > 0)
         }
+
+        @WorkerThread
+        override fun onAccountRegistrationStateChanged(
+            core: Core,
+            account: Account,
+            state: RegistrationState?,
+            message: String
+        ) {
+            when (state) {
+                RegistrationState.Failed -> {
+                    if (account == core.defaultAccount) {
+                        Log.e("$TAG Default account registration failed!")
+                        defaultAccountRegistrationFailed = true
+                        defaultAccountRegistrationErrorEvent.postValue(Event(true))
+                    } else {
+                        // TODO: show red top bar for non-default account registration failure
+                    }
+                }
+                RegistrationState.Ok -> {
+                    if (account == core.defaultAccount && defaultAccountRegistrationFailed) {
+                        Log.i("$TAG Default account is now registered")
+                        defaultAccountRegistrationFailed = false
+                        defaultAccountRegistrationErrorEvent.postValue(Event(false))
+                    } else {
+                        // TODO: hide red top bar for non-default account registration failure
+                    }
+                }
+                else -> {}
+            }
+        }
     }
 
     init {
+        defaultAccountRegistrationFailed = false
+
         coreContext.postOnCoreThread { core ->
             core.addListener(coreListener)
 
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 0c777543c..89f52ef56 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -108,6 +108,7 @@
     <string name="toast_alert_low_cellular_signal">Low cellular signal!</string>
     <string name="toast_alert_low_cellular_signal_cleared">Cellular signal is no longer low</string>
     <string name="toast_call_can_be_trusted">This call can be trusted</string>
+    <string name="toast_default_account_connection_state_error">Connection error!</string>
 
     <string name="assistant_account_login">Login</string>
     <string name="assistant_scan_qr_code">Scan QR code</string>