diff --git a/app/src/main/java/org/linphone/contacts/ContactsManager.java b/app/src/main/java/org/linphone/contacts/ContactsManager.java
index 7e6b49d77..0303baf3b 100644
--- a/app/src/main/java/org/linphone/contacts/ContactsManager.java
+++ b/app/src/main/java/org/linphone/contacts/ContactsManager.java
@@ -350,26 +350,44 @@ public class ContactsManager extends ContentObserver implements FriendListListen
 
     public synchronized LinphoneContact findContactFromPhoneNumber(String phoneNumber) {
         if (phoneNumber == null) return null;
+
+        if (!android.util.Patterns.PHONE.matcher(phoneNumber).matches()) {
+            Log.w(
+                    "[Contacts Manager] Expected phone number but doesn't look like it: "
+                            + phoneNumber);
+            return null;
+        }
+
         Core core = LinphoneManager.getCore();
         ProxyConfig lpc = null;
         if (core != null) {
             lpc = core.getDefaultProxyConfig();
         }
-        if (lpc == null) return null;
+        if (lpc == null) {
+            Log.i("[Contacts Manager] Couldn't find default proxy config...");
+            return null;
+        }
+
         String normalized = lpc.normalizePhoneNumber(phoneNumber);
-        if (normalized == null) normalized = phoneNumber;
+        if (normalized == null) {
+            Log.w("[Contacts Manager] Couldn't normalize phone number " + phoneNumber + ", default proxy config prefix is " + lpc.getDialPrefix());
+            normalized = phoneNumber;
+        }
 
         Address addr = lpc.normalizeSipUri(normalized);
         if (addr == null) {
+            Log.w("[Contacts Manager] Couldn't normalize SIP URI " + normalized);
             return null;
         }
+
+        // Without this, the hashmap inside liblinphone won't find it...
         addr.setUriParam("user", "phone");
-        Friend lf =
-                core.findFriend(
-                        addr); // Without this, the hashmap inside liblinphone won't find it...
+        Friend lf = core.findFriend(addr);
         if (lf != null) {
             return (LinphoneContact) lf.getUserData();
         }
+        
+        Log.w("[Contacts Manager] Couldn't find friend...");
         return null;
     }
 
diff --git a/app/src/main/res/layout/settings_account.xml b/app/src/main/res/layout/settings_account.xml
index 5c5083888..99b818395 100644
--- a/app/src/main/res/layout/settings_account.xml
+++ b/app/src/main/res/layout/settings_account.xml
@@ -137,7 +137,8 @@
             android:id="@+id/pref_prefix"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            linphone:hint="@string/pref_prefix"
+            linphone:hint="@string/pref_prefix_desc"
+            linphone:subtitle="@string/pref_prefix_desc"
             linphone:title="@string/pref_prefix" />
 
         <org.linphone.settings.widget.SwitchSetting
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index bd87aa6ac..def0ec44d 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -367,6 +367,7 @@
     <string name="pref_display_name">Display name</string>
     <string name="pref_help_display_name">Enter display name (optional)</string>
     <string name="pref_prefix">Prefix</string>
+    <string name="pref_prefix_desc">Prefix for your country (without the +)</string>
     <string name="pref_transport">Transport</string>
     <string name="pref_transport_udp">UDP</string>
     <string name="pref_transport_tcp">TCP</string>