diff --git a/core/api/current.txt b/core/api/current.txt
index cf5a261..e957676 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -44544,6 +44544,7 @@
     method @Nullable public android.telephony.CellIdentity getCellIdentity();
     method public int getDomain();
     method @Nullable public String getRegisteredPlmn();
+    method @FlaggedApi("com.android.internal.telephony.flags.network_registration_info_reject_cause") public int getRejectCause();
     method public int getTransportType();
     method public boolean isNetworkRegistered();
     method public boolean isNetworkRoaming();
diff --git a/core/api/system-current.txt b/core/api/system-current.txt
index 86f2b628..6afc948 100644
--- a/core/api/system-current.txt
+++ b/core/api/system-current.txt
@@ -14128,7 +14128,6 @@
     method @Nullable public android.telephony.DataSpecificRegistrationInfo getDataSpecificInfo();
     method public int getNetworkRegistrationState();
     method @Deprecated public int getRegistrationState();
-    method public int getRejectCause();
     method public int getRoamingType();
     method public boolean isEmergencyEnabled();
     method public void writeToParcel(android.os.Parcel, int);
diff --git a/telephony/java/android/telephony/NetworkRegistrationInfo.java b/telephony/java/android/telephony/NetworkRegistrationInfo.java
index 7ccc27e..0c324e6 100644
--- a/telephony/java/android/telephony/NetworkRegistrationInfo.java
+++ b/telephony/java/android/telephony/NetworkRegistrationInfo.java
@@ -649,12 +649,19 @@
     }
 
     /**
-     * @return Reason for denial if the registration state is {@link #REGISTRATION_STATE_DENIED}.
-     * Depending on {@code accessNetworkTechnology}, the values are defined in 3GPP TS 24.008
-     * 10.5.3.6 for UMTS, 3GPP TS 24.301 9.9.3.9 for LTE, and 3GPP2 A.S0001 6.2.2.44 for CDMA
-     * @hide
+     * Get the 3GPP/3GPP2 reason code indicating why registration failed.
+     *
+     * Returns the reason code for non-transient registration failures. Typically this method will
+     * only return the last reason code received during a network selection procedure. The reason
+     * code is system-specific; however, the reason codes for both 3GPP and 3GPP2 systems are
+     * largely equivalent across generations.
+     *
+     * @return registration reject cause if available, otherwise 0. Depending on
+     * {@link #getAccessNetworkTechnology}, the values are defined in 3GPP TS 24.008 10.5.3.6 for
+     * WCDMA/UMTS, 3GPP TS 24.301 9.9.3.9 for LTE/EPS, 3GPP 24.501 Annex A for NR/5GS, or 3GPP2
+     * A.S0001 6.2.2.44 for CDMA.
      */
-    @SystemApi
+    @FlaggedApi(Flags.FLAG_NETWORK_REGISTRATION_INFO_REJECT_CAUSE)
     public int getRejectCause() {
         return mRejectCause;
     }