diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index e8cffa9..b465dbd 100644
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -1895,6 +1895,27 @@
     }
 
     /**
+     * Check TETHER_DUN_REQUIRED and TETHER_DUN_APN settings, net.tethering.noprovisioning
+     * SystemProperty, and config_tether_apndata to decide whether DUN APN is required for
+     * tethering.
+     *
+     * @return 0: Not required. 1: required. 2: Not set.
+     * @hide
+     */
+    @Override
+    public int getTetherApnRequired() {
+        enforceModifyPermissionOrCarrierPrivilege();
+        int dunRequired = Settings.Global.getInt(mPhone.getContext().getContentResolver(),
+                Settings.Global.TETHER_DUN_REQUIRED, 2);
+        // If not set, check net.tethering.noprovisioning, TETHER_DUN_APN setting and
+        // config_tether_apndata.
+        if (dunRequired == 2 && mPhone.hasMatchedTetherApnSetting()) {
+            dunRequired = 1;
+        }
+        return dunRequired;
+    }
+
+    /**
      * Set mobile data enabled
      * Used by the user through settings etc to turn on/off mobile data
      *