diff --git a/app/src/main/java/org/linphone/ui/assistant/fragment/LoginFragment.kt b/app/src/main/java/org/linphone/ui/assistant/fragment/LoginFragment.kt
index 9bdf4eb87..4a0e3147d 100644
--- a/app/src/main/java/org/linphone/ui/assistant/fragment/LoginFragment.kt
+++ b/app/src/main/java/org/linphone/ui/assistant/fragment/LoginFragment.kt
@@ -132,7 +132,9 @@ class LoginFragment : Fragment() {
 
         coreContext.postOnCoreThread {
             val prefix = PhoneNumberUtils.getDeviceInternationalPrefix(requireContext())
-            viewModel.internationalPrefix.postValue(prefix)
+            if (!prefix.isNullOrEmpty()) {
+                viewModel.internationalPrefix.postValue(prefix)
+            }
         }
     }
 
diff --git a/app/src/main/java/org/linphone/ui/assistant/fragment/RegisterFragment.kt b/app/src/main/java/org/linphone/ui/assistant/fragment/RegisterFragment.kt
index 3b056b9f5..eb0327f4e 100644
--- a/app/src/main/java/org/linphone/ui/assistant/fragment/RegisterFragment.kt
+++ b/app/src/main/java/org/linphone/ui/assistant/fragment/RegisterFragment.kt
@@ -135,7 +135,9 @@ class RegisterFragment : Fragment() {
 
         coreContext.postOnCoreThread {
             val prefix = PhoneNumberUtils.getDeviceInternationalPrefix(requireContext())
-            viewModel.internationalPrefix.postValue("+$prefix")
+            if (!prefix.isNullOrEmpty()) {
+                viewModel.internationalPrefix.postValue("+$prefix")
+            }
         }
     }
 
diff --git a/app/src/main/java/org/linphone/ui/assistant/fragment/ThirdPartySipAccountLoginFragment.kt b/app/src/main/java/org/linphone/ui/assistant/fragment/ThirdPartySipAccountLoginFragment.kt
index c0e228434..49a5ede46 100644
--- a/app/src/main/java/org/linphone/ui/assistant/fragment/ThirdPartySipAccountLoginFragment.kt
+++ b/app/src/main/java/org/linphone/ui/assistant/fragment/ThirdPartySipAccountLoginFragment.kt
@@ -121,7 +121,9 @@ class ThirdPartySipAccountLoginFragment : Fragment() {
 
         coreContext.postOnCoreThread {
             val prefix = PhoneNumberUtils.getDeviceInternationalPrefix(requireContext())
-            viewModel.internationalPrefix.postValue(prefix)
+            if (!prefix.isNullOrEmpty()) {
+                viewModel.internationalPrefix.postValue(prefix)
+            }
         }
     }
 
diff --git a/app/src/main/java/org/linphone/utils/LinphoneUtils.kt b/app/src/main/java/org/linphone/utils/LinphoneUtils.kt
index 371042e2a..7207340e4 100644
--- a/app/src/main/java/org/linphone/utils/LinphoneUtils.kt
+++ b/app/src/main/java/org/linphone/utils/LinphoneUtils.kt
@@ -40,11 +40,11 @@ import org.linphone.core.tools.Log
 
 class LinphoneUtils {
     companion object {
-        private const val TAG = "[App Utils]"
+        private const val TAG = "[Linphone Utils]"
 
         @WorkerThread
         fun getDefaultAccount(): Account? {
-            return coreContext.core.defaultAccount ?: coreContext.core.accountList.first()
+            return coreContext.core.defaultAccount ?: coreContext.core.accountList.firstOrNull()
         }
 
         @AnyThread