diff --git a/core/api/current.txt b/core/api/current.txt
index 82393f427f9b5..da7581442677e 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -34220,6 +34220,7 @@ package android.provider {
     field public static final String AUTHORITY = "service-state";
     field public static final android.net.Uri CONTENT_URI;
     field public static final String DATA_NETWORK_TYPE = "data_network_type";
+    field public static final String DUPLEX_MODE = "duplex_mode";
     field public static final String IS_MANUAL_NETWORK_SELECTION = "is_manual_network_selection";
     field public static final String VOICE_OPERATOR_NUMERIC = "voice_operator_numeric";
     field public static final String VOICE_REG_STATE = "voice_reg_state";
diff --git a/core/java/android/provider/Telephony.java b/core/java/android/provider/Telephony.java
index 9b65a7ce0509e..ddeb955e6ad06 100644
--- a/core/java/android/provider/Telephony.java
+++ b/core/java/android/provider/Telephony.java
@@ -4579,6 +4579,17 @@ public final class Telephony {
          * This is the same as {@link TelephonyManager#getDataNetworkType()}.
          */
         public static final String DATA_NETWORK_TYPE = "data_network_type";
+
+        /**
+         * An integer value indicating the current duplex mode if the radio technology is LTE,
+         * LTE-CA or NR.
+         * <p>
+         * Valid values: {@link ServiceState#DUPLEX_MODE_UNKNOWN},
+         * {@link ServiceState#DUPLEX_MODE_FDD}, {@link ServiceState#DUPLEX_MODE_TDD}.
+         * <p>
+         * This is the same as {@link ServiceState#getDuplexMode()}.
+         */
+        public static final String DUPLEX_MODE = "duplex_mode";
     }
 
     /**