diff --git a/core/java/android/net/NetworkRequest.java b/core/java/android/net/NetworkRequest.java
index c7b3009..3be49d5 100644
--- a/core/java/android/net/NetworkRequest.java
+++ b/core/java/android/net/NetworkRequest.java
@@ -300,22 +300,34 @@
          * this without a single transport set will generate an exception, as will
          * subsequently adding or removing transports after this is set.
          * </p>
-         * The interpretation of this {@code String} is bearer specific and bearers that use
-         * it should document their particulars.  For example, Bluetooth may use some sort of
-         * device id while WiFi could used ssid and/or bssid.  Cellular may use carrier spn.
+         * If the {@code networkSpecifier} is provided, it shall be interpreted as follows:
+         * <ul>
+         * <li>If the specifier can be parsed as an integer, it will be treated as a
+         * {@link android.net TelephonyNetworkSpecifier}, and the provided integer will be
+         * interpreted as a SubscriptionId.
+         * <li>If the value is an ethernet interface name, it will be treated as such.
+         * <li>For all other cases, the behavior is undefined.
+         * </ul>
          *
-         * @param networkSpecifier An {@code String} of opaque format used to specify the bearer
-         *                         specific network specifier where the bearer has a choice of
-         *                         networks.
+         * @param networkSpecifier A {@code String} of either a SubscriptionId in cellular
+         *                         network request or an ethernet interface name in ethernet
+         *                         network request.
+         *
+         * @deprecated Use {@link #setNetworkSpecifier(NetworkSpecifier)} instead.
          */
+        @Deprecated
         public Builder setNetworkSpecifier(String networkSpecifier) {
-            /*
-             * A StringNetworkSpecifier does not accept null or empty ("") strings. When network
-             * specifiers were strings a null string and an empty string were considered equivalent.
-             * Hence no meaning is attached to a null or empty ("") string.
-             */
-            return setNetworkSpecifier(TextUtils.isEmpty(networkSpecifier) ? null
-                    : new StringNetworkSpecifier(networkSpecifier));
+            try {
+                int subId = Integer.parseInt(networkSpecifier);
+                return setNetworkSpecifier(new TelephonyNetworkSpecifier.Builder()
+                        .setSubscriptionId(subId).build());
+            } catch (NumberFormatException nfe) {
+                // A StringNetworkSpecifier does not accept null or empty ("") strings. When network
+                // specifiers were strings a null string and an empty string were considered
+                // equivalent. Hence no meaning is attached to a null or empty ("") string.
+                return setNetworkSpecifier(TextUtils.isEmpty(networkSpecifier) ? null
+                        : new StringNetworkSpecifier(networkSpecifier));
+            }
         }
 
         /**
diff --git a/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java b/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java
index 2179518..2c41557 100644
--- a/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java
+++ b/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java
@@ -28,7 +28,7 @@
 import android.content.Intent;
 import android.content.res.Resources;
 import android.net.NetworkSpecifier;
-import android.net.StringNetworkSpecifier;
+import android.net.TelephonyNetworkSpecifier;
 import android.net.wifi.WifiInfo;
 import android.os.UserHandle;
 import android.telephony.SubscriptionManager;
@@ -223,14 +223,8 @@
                     // name has been added to it
                     NetworkSpecifier specifier = nai.networkCapabilities.getNetworkSpecifier();
                     int subId = SubscriptionManager.DEFAULT_SUBSCRIPTION_ID;
-                    if (specifier instanceof StringNetworkSpecifier) {
-                        try {
-                            subId = Integer.parseInt(
-                                    ((StringNetworkSpecifier) specifier).specifier);
-                        } catch (NumberFormatException e) {
-                            Slog.e(TAG, "NumberFormatException on "
-                                    + ((StringNetworkSpecifier) specifier).specifier);
-                        }
+                    if (specifier instanceof TelephonyNetworkSpecifier) {
+                        subId = ((TelephonyNetworkSpecifier) specifier).getSubscriptionId();
                     }
 
                     details = mTelephonyManager.createForSubscriptionId(subId)
diff --git a/tests/net/java/android/net/TelephonyNetworkSpecifierTest.java b/tests/net/java/android/net/TelephonyNetworkSpecifierTest.java
new file mode 100644
index 0000000..47afed4
--- /dev/null
+++ b/tests/net/java/android/net/TelephonyNetworkSpecifierTest.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import static com.android.testutils.ParcelUtilsKt.assertParcelSane;
+
+import static org.junit.Assert.assertEquals;
+
+import android.telephony.SubscriptionManager;
+
+import androidx.test.filters.SmallTest;
+
+import org.junit.Test;
+
+/**
+ * Unit test for {@link android.net.TelephonyNetworkSpecifier}.
+ */
+@SmallTest
+public class TelephonyNetworkSpecifierTest {
+    private static final int TEST_SUBID = 5;
+
+    /**
+     * Validate that IllegalArgumentException will be thrown if build TelephonyNetworkSpecifier
+     * without calling {@link TelephonyNetworkSpecifier.Builder#setSubscriptionId(int)}.
+     */
+    @Test
+    public void testBuilderBuildWithDefault() {
+        try {
+            new TelephonyNetworkSpecifier.Builder().build();
+        } catch (IllegalArgumentException iae) {
+            // expected, test pass
+        }
+    }
+
+    /**
+     * Validate that no exception will be thrown even if pass invalid subscription id to
+     * {@link TelephonyNetworkSpecifier.Builder#setSubscriptionId(int)}.
+     */
+    @Test
+    public void testBuilderBuildWithInvalidSubId() {
+        TelephonyNetworkSpecifier specifier = new TelephonyNetworkSpecifier.Builder()
+                .setSubscriptionId(SubscriptionManager.INVALID_SUBSCRIPTION_ID)
+                .build();
+        assertEquals(specifier.getSubscriptionId(), SubscriptionManager.INVALID_SUBSCRIPTION_ID);
+    }
+
+    /**
+     * Validate the correctness of TelephonyNetworkSpecifier when provide valid subId.
+     */
+    @Test
+    public void testBuilderBuildWithValidSubId() {
+        final TelephonyNetworkSpecifier specifier = new TelephonyNetworkSpecifier.Builder()
+                .setSubscriptionId(TEST_SUBID)
+                .build();
+        assertEquals(TEST_SUBID, specifier.getSubscriptionId());
+    }
+
+    /**
+     * Validate that parcel marshalling/unmarshalling works.
+     */
+    @Test
+    public void testParcel() {
+        TelephonyNetworkSpecifier specifier = new TelephonyNetworkSpecifier.Builder()
+                .setSubscriptionId(TEST_SUBID)
+                .build();
+        assertParcelSane(specifier, 1 /* fieldCount */);
+    }
+}
diff --git a/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java b/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java
index b783467..de1028c 100644
--- a/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java
+++ b/tests/net/java/com/android/server/connectivity/MultipathPolicyTrackerTest.java
@@ -51,6 +51,7 @@
 import android.net.NetworkPolicyManager;
 import android.net.NetworkTemplate;
 import android.net.StringNetworkSpecifier;
+import android.net.TelephonyNetworkSpecifier;
 import android.os.Handler;
 import android.provider.Settings;
 import android.telephony.TelephonyManager;
@@ -229,7 +230,7 @@
         verify(mCM).registerNetworkCallback(any(), networkCallback.capture(), any());
 
         // Simulate callback after capability changes
-        final NetworkCapabilities capabilities = new NetworkCapabilities()
+        NetworkCapabilities capabilities = new NetworkCapabilities()
                 .addCapability(NET_CAPABILITY_INTERNET)
                 .addTransportType(TRANSPORT_CELLULAR)
                 .setNetworkSpecifier(new StringNetworkSpecifier("234"));
@@ -239,6 +240,19 @@
         networkCallback.getValue().onCapabilitiesChanged(
                 TEST_NETWORK,
                 capabilities);
+
+        // make sure it also works with the new introduced  TelephonyNetworkSpecifier
+        capabilities = new NetworkCapabilities()
+                .addCapability(NET_CAPABILITY_INTERNET)
+                .addTransportType(TRANSPORT_CELLULAR)
+                .setNetworkSpecifier(new TelephonyNetworkSpecifier.Builder()
+                        .setSubscriptionId(234).build());
+        if (!roaming) {
+            capabilities.addCapability(NET_CAPABILITY_NOT_ROAMING);
+        }
+        networkCallback.getValue().onCapabilitiesChanged(
+                TEST_NETWORK,
+                capabilities);
     }
 
     @Test