diff --git a/src/com/android/phone/ImsRcsController.java b/src/com/android/phone/ImsRcsController.java
index 6b1b5e3..3ea8df2 100644
--- a/src/com/android/phone/ImsRcsController.java
+++ b/src/com/android/phone/ImsRcsController.java
@@ -361,8 +361,8 @@
         int slotId = phone.getPhoneId();
         RcsFeatureController c = mRcsService.getFeatureController(slotId);
         if (c == null) {
-            throw new ServiceSpecificException(ImsException.CODE_ERROR_SERVICE_UNAVAILABLE,
-                    "Cannot find RcsFeatureController instance for sub: " + subId);
+            throw new ServiceSpecificException(ImsException.CODE_ERROR_UNSUPPORTED_OPERATION,
+                    "The requested operation is not supported for subId " + subId);
         }
         return c;
     }
diff --git a/src/com/android/services/telephony/rcs/RcsFeatureController.java b/src/com/android/services/telephony/rcs/RcsFeatureController.java
index f451e9b..5094c57 100644
--- a/src/com/android/services/telephony/rcs/RcsFeatureController.java
+++ b/src/com/android/services/telephony/rcs/RcsFeatureController.java
@@ -125,7 +125,7 @@
                 public void connectionReady(RcsFeatureManager manager)
                         throws com.android.ims.ImsException {
                     if (manager == null) {
-                        Log.w(LOG_TAG, "connectionReady returned null RcsFeatureManager");
+                        logw("connectionReady returned null RcsFeatureManager");
                         return;
                     }
                     try {
@@ -192,6 +192,7 @@
      */
     public void connect() {
         synchronized (mLock) {
+            if (mFeatureConnector != null) return;
             mFeatureConnector = mFeatureFactory.create(mContext, mSlotId, mFeatureConnectorListener,
                     mContext.getMainExecutor(), LOG_TAG);
             mFeatureConnector.connect();
@@ -224,6 +225,25 @@
     }
 
     /**
+     * Removes the feature associated with this class.
+     */
+    public <T> void removeFeature(Class<T> clazz) {
+        synchronized (mLock) {
+            RcsFeatureController.Feature feature = mFeatures.remove(clazz);
+            feature.onDestroy();
+        }
+    }
+
+    /**
+     * @return true if this controller has features it is actively tracking.
+     */
+    public boolean hasActiveFeatures() {
+        synchronized (mLock) {
+            return mFeatures.size() > 0;
+        }
+    }
+
+    /**
      * Update the subscription associated with this controller.
      */
     public void updateAssociatedSubscription(int newSubId) {
@@ -247,7 +267,10 @@
      */
     public void destroy() {
         synchronized (mLock) {
-            mFeatureConnector.disconnect();
+            Log.i(LOG_TAG, "destroy: slotId=" + mSlotId);
+            if (mFeatureConnector != null) {
+                mFeatureConnector.disconnect();
+            }
             for (Feature c : mFeatures.values()) {
                 c.onRcsDisconnected();
                 c.onDestroy();
@@ -406,4 +429,15 @@
             pw.println(mFeatureManager != null);
         }
     }
+
+    private void logw(String log) {
+        Log.w(LOG_TAG, getLogPrefix().append(log).toString());
+    }
+
+    private StringBuilder getLogPrefix() {
+        StringBuilder sb = new StringBuilder("[");
+        sb.append(mSlotId);
+        sb.append("] ");
+        return sb;
+    }
 }
diff --git a/src/com/android/services/telephony/rcs/TelephonyRcsService.java b/src/com/android/services/telephony/rcs/TelephonyRcsService.java
index b4223d3..c85e9a9 100644
--- a/src/com/android/services/telephony/rcs/TelephonyRcsService.java
+++ b/src/com/android/services/telephony/rcs/TelephonyRcsService.java
@@ -28,6 +28,7 @@
 import android.telephony.CarrierConfigManager;
 import android.telephony.SubscriptionManager;
 import android.util.Log;
+import android.util.SparseArray;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.telephony.PhoneConfigurationManager;
@@ -35,8 +36,6 @@
 
 import java.io.FileDescriptor;
 import java.io.PrintWriter;
-import java.util.ArrayList;
-import java.util.List;
 
 /**
  * Singleton service setup to manage RCS related services that the platform provides such as User
@@ -85,8 +84,8 @@
     private final Object mLock = new Object();
     private int mNumSlots;
 
-    // Index corresponds to the slot ID.
-    private List<RcsFeatureController> mFeatureControllers;
+    // Maps slot ID -> RcsFeatureController.
+    private SparseArray<RcsFeatureController> mFeatureControllers;
 
     private BroadcastReceiver mCarrierConfigChangedReceiver = new BroadcastReceiver() {
         @Override
@@ -99,8 +98,10 @@
                 if (bundle == null) {
                     return;
                 }
-                int slotId = bundle.getInt(CarrierConfigManager.EXTRA_SLOT_INDEX);
-                int subId = bundle.getInt(CarrierConfigManager.EXTRA_SUBSCRIPTION_INDEX);
+                int slotId = bundle.getInt(CarrierConfigManager.EXTRA_SLOT_INDEX,
+                        SubscriptionManager.INVALID_PHONE_INDEX);
+                int subId = bundle.getInt(CarrierConfigManager.EXTRA_SUBSCRIPTION_INDEX,
+                        SubscriptionManager.INVALID_SUBSCRIPTION_ID);
                 updateFeatureControllerSubscription(slotId, subId);
             }
         }
@@ -125,10 +126,9 @@
     });
 
     public TelephonyRcsService(Context context, int numSlots) {
-        Log.i(LOG_TAG, "initialize");
         mContext = context;
         mNumSlots = numSlots;
-        mFeatureControllers = new ArrayList<>(numSlots);
+        mFeatureControllers = new SparseArray<>(numSlots);
     }
 
     /**
@@ -145,11 +145,7 @@
      * system callbacks.
      */
     public void initialize() {
-        synchronized (mLock) {
-            for (int i = 0; i < mNumSlots; i++) {
-                mFeatureControllers.add(constructFeatureController(i));
-            }
-        }
+        updateFeatureControllerSize(mNumSlots);
 
         PhoneConfigurationManager.registerForMultiSimConfigChange(mHandler,
                 HANDLER_MSIM_CONFIGURATION_CHANGE, null);
@@ -173,15 +169,24 @@
             if (oldNumSlots == newNumSlots) {
                 return;
             }
+            Log.i(LOG_TAG, "updateFeatureControllers: oldSlots=" + oldNumSlots + ", newNumSlots="
+                    + newNumSlots);
             mNumSlots = newNumSlots;
             if (oldNumSlots < newNumSlots) {
                 for (int i = oldNumSlots; i < newNumSlots; i++) {
-                    mFeatureControllers.add(constructFeatureController(i));
+                    RcsFeatureController c = constructFeatureController(i);
+                    // Do not add feature controllers for inactive subscriptions
+                    if (c.hasActiveFeatures()) {
+                        mFeatureControllers.put(i, c);
+                    }
                 }
             } else {
                 for (int i = (oldNumSlots - 1); i > (newNumSlots - 1); i--) {
-                    RcsFeatureController controller = mFeatureControllers.remove(i);
-                    controller.destroy();
+                    RcsFeatureController c = mFeatureControllers.get(i);
+                    if (c != null) {
+                        mFeatureControllers.remove(i);
+                        c.destroy();
+                    }
                 }
             }
         }
@@ -190,24 +195,62 @@
     private void updateFeatureControllerSubscription(int slotId, int newSubId) {
         synchronized (mLock) {
             RcsFeatureController f = mFeatureControllers.get(slotId);
-            if (f == null) {
-                Log.w(LOG_TAG, "unexpected null FeatureContainer for slot " + slotId);
-                return;
+            Log.i(LOG_TAG, "updateFeatureControllerSubscription: slotId=" + slotId + " newSubId="
+                    + newSubId + ", existing feature=" + (f != null));
+            if (SubscriptionManager.isValidSubscriptionId(newSubId)) {
+                if (f == null) {
+                    // A controller doesn't exist for this slot yet.
+                    f = mFeatureFactory.createController(mContext, slotId);
+                    updateSupportedFeatures(f, slotId, newSubId);
+                    if (f.hasActiveFeatures()) mFeatureControllers.put(slotId, f);
+                } else {
+                    updateSupportedFeatures(f, slotId, newSubId);
+                    // Do not keep an empty container around.
+                    if (!f.hasActiveFeatures()) {
+                        f.destroy();
+                        mFeatureControllers.remove(slotId);
+                    }
+                }
             }
-            f.updateAssociatedSubscription(newSubId);
+            if (f != null) f.updateAssociatedSubscription(newSubId);
         }
     }
 
     private RcsFeatureController constructFeatureController(int slotId) {
         RcsFeatureController c = mFeatureFactory.createController(mContext, slotId);
-        // TODO: integrate user setting into whether or not this feature is added as well as logic
-        // to listen for changes in user setting.
-        c.addFeature(mFeatureFactory.createUserCapabilityExchange(mContext, slotId,
-                getSubscriptionFromSlot(slotId)), UserCapabilityExchangeImpl.class);
-        c.connect();
+        int subId = getSubscriptionFromSlot(slotId);
+        updateSupportedFeatures(c, slotId, subId);
         return c;
     }
 
+    private void updateSupportedFeatures(RcsFeatureController c, int slotId, int subId) {
+        if (doesSubscriptionSupportPresence(subId)) {
+            if (c.getFeature(UserCapabilityExchangeImpl.class) == null) {
+                c.addFeature(mFeatureFactory.createUserCapabilityExchange(mContext, slotId, subId),
+                        UserCapabilityExchangeImpl.class);
+            }
+        } else {
+            if (c.getFeature(UserCapabilityExchangeImpl.class) != null) {
+                c.removeFeature(UserCapabilityExchangeImpl.class);
+            }
+        }
+        // Only start the connection procedure if we have active features.
+        if (c.hasActiveFeatures()) c.connect();
+    }
+
+    private boolean doesSubscriptionSupportPresence(int subId) {
+        if (!SubscriptionManager.isValidSubscriptionId(subId)) return false;
+        CarrierConfigManager carrierConfigManager =
+                mContext.getSystemService(CarrierConfigManager.class);
+        if (carrierConfigManager == null) return false;
+        boolean supportsUce = carrierConfigManager.getConfigForSubId(subId).getBoolean(
+                CarrierConfigManager.KEY_USE_RCS_PRESENCE_BOOL);
+        supportsUce |= carrierConfigManager.getConfigForSubId(subId).getBoolean(
+                CarrierConfigManager.KEY_USE_RCS_SIP_OPTIONS_BOOL);
+        return supportsUce;
+    }
+
+
     private int getSubscriptionFromSlot(int slotId) {
         SubscriptionManager manager = mContext.getSystemService(SubscriptionManager.class);
         if (manager == null) {
@@ -229,7 +272,8 @@
         pw.println("RcsFeatureControllers:");
         pw.increaseIndent();
         synchronized (mLock) {
-            for (RcsFeatureController f : mFeatureControllers) {
+            for (int i = 0; i < mNumSlots; i++) {
+                RcsFeatureController f = mFeatureControllers.get(i);
                 pw.increaseIndent();
                 f.dump(fd, printWriter, args);
                 pw.decreaseIndent();
diff --git a/src/com/android/services/telephony/rcs/UserCapabilityExchangeImpl.java b/src/com/android/services/telephony/rcs/UserCapabilityExchangeImpl.java
index 7521205..d488dff 100644
--- a/src/com/android/services/telephony/rcs/UserCapabilityExchangeImpl.java
+++ b/src/com/android/services/telephony/rcs/UserCapabilityExchangeImpl.java
@@ -44,7 +44,7 @@
 public class UserCapabilityExchangeImpl implements RcsFeatureController.Feature, SubscribePublisher,
         PresencePublisher {
 
-    private static final String LOG_TAG = "UserCapabilityExchangeImpl";
+    private static final String LOG_TAG = "RcsUceImpl";
 
     private int mSlotId;
     private int mSubId;
@@ -58,6 +58,7 @@
     UserCapabilityExchangeImpl(Context context, int slotId, int subId) {
         mSlotId = slotId;
         mSubId = subId;
+        logi("created");
 
         String[] volteError = context.getResources().getStringArray(
                 R.array.config_volte_provision_error_on_publish_response);
@@ -78,7 +79,7 @@
     // Runs on main thread.
     @Override
     public void onRcsConnected(RcsFeatureManager rcsFeatureManager) {
-        Log.i(LOG_TAG, "onRcsConnected: slotId=" + mSlotId + ", subId=" + mSubId);
+        logi("onRcsConnected");
         mPresencePublication.updatePresencePublisher(this);
         mPresenceSubscriber.updatePresenceSubscriber(this);
     }
@@ -86,7 +87,7 @@
     // Runs on main thread.
     @Override
     public void onRcsDisconnected() {
-        Log.i(LOG_TAG, "onRcsDisconnected: phoneId=" + mSlotId + ", subId=" + mSubId);
+        logi("onRcsDisconnected");
         mPresencePublication.removePresencePublisher();
         mPresenceSubscriber.removePresenceSubscriber();
     }
@@ -127,7 +128,7 @@
                 new ContactCapabilityResponse() {
                     @Override
                     public void onSuccess(int reqId) {
-                        Log.i(LOG_TAG, "onSuccess called for reqId:" + reqId);
+                        logi("onSuccess called for reqId:" + reqId);
                     }
 
                     @Override
@@ -137,16 +138,16 @@
                             if (c != null) {
                                 c.onError(toUceError(resultCode));
                             } else {
-                                Log.w(LOG_TAG, "onError called for unknown reqId:" + reqId);
+                                logw("onError called for unknown reqId:" + reqId);
                             }
                         } catch (RemoteException e) {
-                            Log.i(LOG_TAG, "Calling back to dead service");
+                            logi("Calling back to dead service");
                         }
                     }
 
                     @Override
                     public void onFinish(int reqId) {
-                        Log.i(LOG_TAG, "onFinish called for reqId:" + reqId);
+                        logi("onFinish called for reqId:" + reqId);
                     }
 
                     @Override
@@ -156,10 +157,10 @@
                             if (c != null) {
                                 c.onError(RcsUceAdapter.ERROR_REQUEST_TIMEOUT);
                             } else {
-                                Log.w(LOG_TAG, "onTimeout called for unknown reqId:" + reqId);
+                                logw("onTimeout called for unknown reqId:" + reqId);
                             }
                         } catch (RemoteException e) {
-                            Log.i(LOG_TAG, "Calling back to dead service");
+                            logi("Calling back to dead service");
                         }
                     }
 
@@ -172,10 +173,10 @@
                             if (c != null) {
                                 c.onCapabilitiesReceived(contactCapabilities);
                             } else {
-                                Log.w(LOG_TAG, "onCapabilitiesUpdated, unknown reqId:" + reqId);
+                                logw("onCapabilitiesUpdated, unknown reqId:" + reqId);
                             }
                         } catch (RemoteException e) {
-                            Log.w(LOG_TAG, "onCapabilitiesUpdated on dead service");
+                            logw("onCapabilitiesUpdated on dead service");
                         }
                     }
                 });
@@ -184,7 +185,7 @@
                 c.onError(toUceError(taskId));
                 return;
             } catch (RemoteException e) {
-                Log.i(LOG_TAG, "Calling back to dead service");
+                logi("Calling back to dead service");
             }
         }
         mPendingCapabilityRequests.put(taskId, c);
@@ -272,4 +273,21 @@
                 return RcsUceAdapter.ERROR_GENERIC_FAILURE;
         }
     }
+
+    private void logi(String log) {
+        Log.i(LOG_TAG, getLogPrefix().append(log).toString());
+    }
+
+    private void logw(String log) {
+        Log.w(LOG_TAG, getLogPrefix().append(log).toString());
+    }
+
+    private StringBuilder getLogPrefix() {
+        StringBuilder builder = new StringBuilder("[");
+        builder.append(mSlotId);
+        builder.append("->");
+        builder.append(mSubId);
+        builder.append("] ");
+        return builder;
+    }
 }