diff --git a/api/system-current.txt b/api/system-current.txt
index 593b45db58090..9200ce579affe 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -7424,6 +7424,7 @@ package android.telephony.ims.feature {
   public abstract class ImsFeature {
     ctor public ImsFeature();
     method public abstract void changeEnabledCapabilities(android.telephony.ims.feature.CapabilityChangeRequest, android.telephony.ims.feature.ImsFeature.CapabilityCallbackProxy);
+    method public final int getSlotIndex();
     method public abstract void onFeatureReady();
     method public abstract void onFeatureRemoved();
     method public final void setFeatureState(int);
@@ -7437,7 +7438,7 @@ package android.telephony.ims.feature {
     field public static final int STATE_UNAVAILABLE = 0; // 0x0
   }
 
-  @Deprecated public static class ImsFeature.Capabilities {
+  public static class ImsFeature.Capabilities {
     field @Deprecated protected int mCapabilities;
   }
 
diff --git a/telephony/java/android/telephony/ims/feature/ImsFeature.java b/telephony/java/android/telephony/ims/feature/ImsFeature.java
index 74af6bf6fe6e9..3bec8b000bb71 100644
--- a/telephony/java/android/telephony/ims/feature/ImsFeature.java
+++ b/telephony/java/android/telephony/ims/feature/ImsFeature.java
@@ -132,15 +132,20 @@ public abstract class ImsFeature {
     public @interface ImsState {}
 
     /**
-     * This {@link ImsFeature}'s state is unavailable and should not be communicated with.
+     * This {@link ImsFeature}'s state is unavailable and should not be communicated with. This will
+     * remove all bindings back to the framework. Any attempt to communicate with the framework
+     * during this time will result in an {@link IllegalStateException}.
      */
     public static final int STATE_UNAVAILABLE = 0;
     /**
-     * This {@link ImsFeature} state is initializing and should not be communicated with.
+     * This {@link ImsFeature} state is initializing and should not be communicated with. This will
+     * remove all bindings back to the framework. Any attempt to communicate with the framework
+     * during this time will result in an {@link IllegalStateException}.
      */
     public static final int STATE_INITIALIZING = 1;
     /**
-     * This {@link ImsFeature} is ready for communication.
+     * This {@link ImsFeature} is ready for communication. Do not attempt to call framework methods
+     * until {@link #onFeatureReady()} is called.
      */
     public static final int STATE_READY = 2;
 
@@ -208,11 +213,14 @@ public abstract class ImsFeature {
 
     /**
      * Contains the capabilities defined and supported by an ImsFeature in the form of a bit mask.
+     * <p>
+     * Typically this class is not used directly, but rather extended in subclasses of
+     * {@link ImsFeature} to provide service specific capabilities.
      * @hide
-     * @deprecated Use {@link MmTelFeature.MmTelCapabilities} instead.
      */
-    @SystemApi  // SystemApi only because it was leaked through type usage in a previous release.
+    @SystemApi
     public static class Capabilities {
+        /** @deprecated Use getters and accessors instead. */
         protected int mCapabilities = 0;
 
         /**
@@ -305,12 +313,12 @@ public abstract class ImsFeature {
     /** @hide */
     protected final Object mLock = new Object();
 
-    private final Set<IImsFeatureStatusCallback> mStatusCallbacks = Collections.newSetFromMap(
-            new WeakHashMap<IImsFeatureStatusCallback, Boolean>());
+    private final Set<IImsFeatureStatusCallback> mStatusCallbacks =
+            Collections.newSetFromMap(new WeakHashMap<>());
     private @ImsState int mState = STATE_UNAVAILABLE;
     private int mSlotId = SubscriptionManager.INVALID_SIM_SLOT_INDEX;
-    private final RemoteCallbackList<IImsCapabilityCallback> mCapabilityCallbacks
-            = new RemoteCallbackList<>();
+    private final RemoteCallbackList<IImsCapabilityCallback> mCapabilityCallbacks =
+            new RemoteCallbackList<>();
     private Capabilities mCapabilityStatus = new Capabilities();
 
     /**
@@ -321,6 +329,16 @@ public abstract class ImsFeature {
         mSlotId = slotId;
     }
 
+    /**
+     * @return The SIM slot index associated with this ImsFeature.
+     *
+     * @see SubscriptionManager#getSubscriptionIds(int) for more information on getting the
+     * subscription IDs associated with this slot.
+     */
+    public final int getSlotIndex() {
+        return mSlotId;
+    }
+
     /**
      * @return The current state of the feature, defined as {@link #STATE_UNAVAILABLE},
      * {@link #STATE_INITIALIZING}, or {@link #STATE_READY}.
@@ -490,7 +508,9 @@ public abstract class ImsFeature {
     public abstract void onFeatureRemoved();
 
     /**
-     * Called when the feature has been initialized and communication with the framework is set up.
+     * Called after this ImsFeature has been initialized and has been set to the
+     * {@link ImsState#STATE_READY} state.
+     * <p>
      * Any attempt by this feature to access the framework before this method is called will return
      * with an {@link IllegalStateException}.
      * The IMS provider should use this method to trigger registration for this feature on the IMS