diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 5754e60..a0652f7c 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -3620,6 +3620,13 @@
                 "pdp_watchdog_max_pdp_reset_fail_count";
 
         /**
+         * The number of milliseconds to delay when checking for data stalls
+         * @hide
+         */
+        public static final String DATA_STALL_ALARM_DELAY_IN_MS =
+                "data_stall_alarm_delay_in_ms";
+
+        /**
          * The interval in milliseconds at which to check gprs registration
          * after the first registration mismatch of gprs and voice service,
          * to detect possible data network registration problems.
diff --git a/telephony/java/com/android/internal/telephony/DataConnectionTracker.java b/telephony/java/com/android/internal/telephony/DataConnectionTracker.java
index 97e7aa3..5b13603 100644
--- a/telephony/java/com/android/internal/telephony/DataConnectionTracker.java
+++ b/telephony/java/com/android/internal/telephony/DataConnectionTracker.java
@@ -27,12 +27,14 @@
 import android.net.LinkCapabilities;
 import android.net.LinkProperties;
 import android.net.NetworkInfo;
+import android.net.TrafficStats;
 import android.net.wifi.WifiManager;
 import android.os.AsyncResult;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.os.Messenger;
+import android.os.SystemClock;
 import android.os.SystemProperties;
 import android.preference.PreferenceManager;
 import android.provider.Settings;
@@ -56,6 +58,7 @@
  */
 public abstract class DataConnectionTracker extends Handler {
     protected static final boolean DBG = true;
+    protected static final boolean VDBG = false;
 
     /**
      * IDLE: ready to start data connection setup, default state
@@ -114,8 +117,8 @@
     protected static final int EVENT_RESTORE_DEFAULT_APN = BASE + 14;
     protected static final int EVENT_DISCONNECT_DONE = BASE + 15;
     protected static final int EVENT_DATA_CONNECTION_ATTACHED = BASE + 16;
-    protected static final int EVENT_START_NETSTAT_POLL = BASE + 17;
-    protected static final int EVENT_START_RECOVERY = BASE + 18;
+    protected static final int EVENT_DATA_STALL_ALARM = BASE + 17;
+    protected static final int EVENT_DO_RECOVERY = BASE + 18;
     protected static final int EVENT_APN_CHANGED = BASE + 19;
     protected static final int EVENT_CDMA_DATA_DETACHED = BASE + 20;
     protected static final int EVENT_NV_READY = BASE + 21;
@@ -189,19 +192,16 @@
 
     /**
      * After detecting a potential connection problem, this is the max number
-     * of subsequent polls before attempting a radio reset.  At this point,
-     * poll interval is 5 seconds (POLL_NETSTAT_SLOW_MILLIS), so set this to
-     * poll for about 2 more minutes.
+     * of subsequent polls before attempting recovery.
      */
     protected static final int NO_RECV_POLL_LIMIT = 24;
-
     // 1 sec. default polling interval when screen is on.
     protected static final int POLL_NETSTAT_MILLIS = 1000;
     // 10 min. default polling interval when screen is off.
     protected static final int POLL_NETSTAT_SCREEN_OFF_MILLIS = 1000*60*10;
     // 2 min for round trip time
     protected static final int POLL_LONGEST_RTT = 120 * 1000;
-    // 10 for packets without ack
+    // Default sent packets without ack which triggers initial recovery steps
     protected static final int NUMBER_SENT_PACKETS_OF_HANG = 10;
     // how long to wait before switching back to default APN
     protected static final int RESTORE_DEFAULT_APN_DELAY = 1 * 60 * 1000;
@@ -210,6 +210,13 @@
     // represents an invalid IP address
     protected static final String NULL_IP = "0.0.0.0";
 
+    // Default for the data stall alarm
+    protected static final int DATA_STALL_ALARM_DELAY_IN_MS_DEFAULT = 1000 * 60 * 3;
+    // If attempt is less than this value we're doing first level recovery
+    protected static final int DATA_STALL_NO_RECV_POLL_LIMIT = 1;
+    // Tag for tracking stale alarms
+    protected static final String DATA_STALL_ALARM_TAG_EXTRA = "data.stall.alram.tag";
+
     // TODO: See if we can remove INTENT_RECONNECT_ALARM
     //       having to have different values for GSM and
     //       CDMA. If so we can then remove the need for
@@ -240,11 +247,19 @@
 
     protected long mTxPkts;
     protected long mRxPkts;
-    protected long mSentSinceLastRecv;
     protected int mNetStatPollPeriod;
-    protected int mNoRecvPollCount = 0;
     protected boolean mNetStatPollEnabled = false;
 
+    protected TxRxSum mDataStallTxRxSum = new TxRxSum(0, 0);
+    // Used to track stale data stall alarms.
+    protected int mDataStallAlarmTag = (int) SystemClock.elapsedRealtime();
+    // The current data stall alarm intent
+    protected PendingIntent mDataStallAlarmIntent = null;
+    // Number of packets sent since the last received packet
+    protected long mSentSinceLastRecv;
+    // Controls when a simple recovery attempt it to be tried
+    protected int mNoRecvPollCount = 0;
+
     // wifi connection status will be updated by sticky intent
     protected boolean mIsWifiConnected = false;
 
@@ -313,7 +328,8 @@
             } else if (action.startsWith(getActionIntentReconnectAlarm())) {
                 log("Reconnect alarm. Previous state was " + mState);
                 onActionIntentReconnectAlarm(intent);
-
+            } else if (action.equals(getActionIntentDataStallAlarm())) {
+                onActionIntentDataStallAlarm(intent);
             } else if (action.equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
                 final android.net.NetworkInfo networkInfo = (NetworkInfo)
                         intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
@@ -363,6 +379,71 @@
         }
     }
 
+    /**
+     * Maintian the sum of transmit and receive packets.
+     *
+     * The packet counts are initizlied and reset to -1 and
+     * remain -1 until they can be updated.
+     */
+    public class TxRxSum {
+        public long txPkts;
+        public long rxPkts;
+
+        public TxRxSum() {
+            reset();
+        }
+
+        public TxRxSum(long txPkts, long rxPkts) {
+            this.txPkts = txPkts;
+            this.rxPkts = rxPkts;
+        }
+
+        public TxRxSum(TxRxSum sum) {
+            txPkts = sum.txPkts;
+            rxPkts = sum.rxPkts;
+        }
+
+        public void reset() {
+            txPkts = -1;
+            rxPkts = -1;
+        }
+
+        public String toString() {
+            return "{txSum=" + txPkts + " rxSum=" + rxPkts + "}";
+        }
+
+        public void updateTxRxSum() {
+            boolean txUpdated = false, rxUpdated = false;
+            long txSum = 0, rxSum = 0;
+            for (ApnContext apnContext : mApnContexts.values()) {
+                if (apnContext.getState() == State.CONNECTED) {
+                    DataConnectionAc dcac = apnContext.getDataConnectionAc();
+                    if (dcac == null) continue;
+
+                    LinkProperties linkProp = dcac.getLinkPropertiesSync();
+                    if (linkProp == null) continue;
+
+                    String iface = linkProp.getInterfaceName();
+
+                    if (iface != null) {
+                        long stats = TrafficStats.getTxPackets(iface);
+                        if (stats > 0) {
+                            txUpdated = true;
+                            txSum += stats;
+                        }
+                        stats = TrafficStats.getRxPackets(iface);
+                        if (stats > 0) {
+                            rxUpdated = true;
+                            rxSum += stats;
+                        }
+                    }
+                }
+            }
+            if (txUpdated) this.txPkts = txSum;
+            if (rxUpdated) this.rxPkts = rxSum;
+        }
+    }
+
     protected boolean isDataSetupCompleteOk(AsyncResult ar) {
         if (ar.exception != null) {
             if (DBG) log("isDataSetupCompleteOk return false, ar.result=" + ar.result);
@@ -394,6 +475,13 @@
         sendMessage(obtainMessage(EVENT_TRY_SETUP_DATA));
     }
 
+    protected void onActionIntentDataStallAlarm(Intent intent) {
+        if (VDBG) log("onActionIntentDataStallAlarm: action=" + intent.getAction());
+        Message msg = obtainMessage(EVENT_DATA_STALL_ALARM, intent.getAction());
+        msg.arg1 = intent.getIntExtra(DATA_STALL_ALARM_TAG_EXTRA, 0);
+        sendMessage(msg);
+    }
+
     /**
      * Default constructor
      */
@@ -529,6 +617,7 @@
 
     // abstract methods
     protected abstract String getActionIntentReconnectAlarm();
+    protected abstract String getActionIntentDataStallAlarm();
     protected abstract void startNetStatPoll();
     protected abstract void stopNetStatPoll();
     protected abstract void restartRadio();
@@ -553,6 +642,10 @@
     protected abstract void onCleanUpAllConnections(String cause);
     protected abstract boolean isDataPossible(String apnType);
 
+    protected void onDataStallAlarm(int tag) {
+        loge("onDataStallAlarm: not impleted tag=" + tag);
+    }
+
     @Override
     public void handleMessage(Message msg) {
         switch (msg.what) {
@@ -575,6 +668,10 @@
                 onTrySetupData(reason);
                 break;
 
+            case EVENT_DATA_STALL_ALARM:
+                onDataStallAlarm(msg.arg1);
+                break;
+
             case EVENT_ROAMING_OFF:
                 if (getDataOnRoamingEnabled() == false) {
                     resetAllRetryCounts();
diff --git a/telephony/java/com/android/internal/telephony/cdma/CdmaDataConnectionTracker.java b/telephony/java/com/android/internal/telephony/cdma/CdmaDataConnectionTracker.java
index f5d05a1..5889372 100644
--- a/telephony/java/com/android/internal/telephony/cdma/CdmaDataConnectionTracker.java
+++ b/telephony/java/com/android/internal/telephony/cdma/CdmaDataConnectionTracker.java
@@ -69,6 +69,10 @@
     private static final String INTENT_RECONNECT_ALARM =
         "com.android.internal.telephony.cdma-reconnect";
 
+    private static final String INTENT_DATA_STALL_ALARM =
+        "com.android.internal.telephony.cdma-data-stall";
+
+
     /**
      * Constants for the data connection activity:
      * physical link down/up
@@ -149,6 +153,11 @@
     }
 
     @Override
+    protected String getActionIntentDataStallAlarm() {
+        return INTENT_DATA_STALL_ALARM;
+    }
+
+    @Override
     protected void setState(State s) {
         if (DBG) log ("setState: " + s);
         if (mState != s) {
diff --git a/telephony/java/com/android/internal/telephony/gsm/GsmDataConnectionTracker.java b/telephony/java/com/android/internal/telephony/gsm/GsmDataConnectionTracker.java
index e166401..b1684f9 100644
--- a/telephony/java/com/android/internal/telephony/gsm/GsmDataConnectionTracker.java
+++ b/telephony/java/com/android/internal/telephony/gsm/GsmDataConnectionTracker.java
@@ -96,22 +96,37 @@
     private boolean mReregisterOnReconnectFailure = false;
     private ContentResolver mResolver;
 
-    // Count of PDP reset attempts; reset when we see incoming,
-    // call reRegisterNetwork, or pingTest succeeds.
-    private int mPdpResetCount = 0;
-
     // Recovery action taken in case of data stall
-    enum RecoveryAction {REREGISTER, RADIO_RESTART, RADIO_RESET};
-    private RecoveryAction mRecoveryAction = RecoveryAction.REREGISTER;
-
+    class RecoveryAction {
+        public static final int GET_DATA_CALL_LIST = 0;
+        public static final int CLEANUP            = 1;
+        public static final int REREGISTER         = 2;
+        public static final int RADIO_RESTART      = 3;
+        public static final int RADIO_RESET        = 4;
+    }
+    public int getRecoveryAction() {
+        int action = Settings.System.getInt(mPhone.getContext().getContentResolver(),
+                "radio.data.stall.recovery.action", RecoveryAction.GET_DATA_CALL_LIST);
+        if (VDBG) log("getRecoveryAction: " + action);
+        return action;
+    }
+    public void putRecoveryAction(int action) {
+        Settings.System.putInt(mPhone.getContext().getContentResolver(),
+                "radio.data.stall.recovery.action", action);
+        if (VDBG) log("putRecoveryAction: " + action);
+    }
 
     //***** Constants
 
     private static final int POLL_PDP_MILLIS = 5 * 1000;
 
-    private static final String INTENT_RECONNECT_ALARM = "com.android.internal.telephony.gprs-reconnect";
+    private static final String INTENT_RECONNECT_ALARM =
+        "com.android.internal.telephony.gprs-reconnect";
     private static final String INTENT_RECONNECT_ALARM_EXTRA_TYPE = "type";
 
+    private static final String INTENT_DATA_STALL_ALARM =
+        "com.android.internal.telephony.gprs-data-stall";
+
     static final Uri PREFERAPN_URI = Uri.parse("content://telephony/carriers/preferapn");
     static final String APN_ID = "apn_id";
     private boolean canSetPreferApn = false;
@@ -163,6 +178,11 @@
         p.getServiceStateTracker().registerForPsRestrictedDisabled(this,
                 EVENT_PS_RESTRICT_DISABLED, null);
 
+        // install reconnect intent filter for this data connection.
+        IntentFilter filter = new IntentFilter();
+        filter.addAction(INTENT_DATA_STALL_ALARM);
+        p.getContext().registerReceiver(mIntentReceiver, filter, null, p);
+
         mDataConnectionTracker = this;
         mResolver = mPhone.getContext().getContentResolver();
 
@@ -241,6 +261,11 @@
         return INTENT_RECONNECT_ALARM;
     }
 
+    @Override
+    protected String getActionIntentDataStallAlarm() {
+        return INTENT_DATA_STALL_ALARM;
+    }
+
     private ApnContext addApnContext(String type) {
         ApnContext apnContext = new ApnContext(type, LOG_TAG);
         apnContext.setDependencyMet(false);
@@ -552,6 +577,7 @@
          */
         if (DBG) log ("onDataConnectionDetached: stop polling and notify detached");
         stopNetStatPoll();
+        stopDataStallAlarm();
         notifyDataConnection(Phone.REASON_DATA_DETACHED);
     }
 
@@ -560,6 +586,7 @@
         if (getOverallState() == State.CONNECTED) {
             if (DBG) log("onDataConnectionAttached: start polling notify attached");
             startNetStatPoll();
+            startDataStallAlarm();
             notifyDataConnection(Phone.REASON_DATA_ATTACHED);
         } else {
             // update APN availability so that APN can be enabled.
@@ -764,6 +791,8 @@
         }
 
         stopNetStatPoll();
+        stopDataStallAlarm();
+
         // TODO: Do we need mRequestedApnType?
         mRequestedApnType = Phone.APN_TYPE_DEFAULT;
     }
@@ -1238,6 +1267,7 @@
         // setState(State.CONNECTED);
         mPhone.notifyDataConnection(apnContext.getReason(), apnContext.getApnType());
         startNetStatPoll();
+        startDataStallAlarm();
         // reset reconnect timer
         apnContext.getDataConnection().resetRetryCount();
     }
@@ -1252,59 +1282,60 @@
     private void resetPollStats() {
         mTxPkts = -1;
         mRxPkts = -1;
-        mSentSinceLastRecv = 0;
         mNetStatPollPeriod = POLL_NETSTAT_MILLIS;
-        mNoRecvPollCount = 0;
     }
 
     private void doRecovery() {
         if (getOverallState() == State.CONNECTED) {
-            int maxPdpReset = Settings.Secure.getInt(mResolver,
-                    Settings.Secure.PDP_WATCHDOG_MAX_PDP_RESET_FAIL_COUNT,
-                    DEFAULT_MAX_PDP_RESET_FAIL);
-            if (mPdpResetCount < maxPdpReset) {
-                mPdpResetCount++;
-                EventLog.writeEvent(EventLogTags.PDP_RADIO_RESET, mSentSinceLastRecv);
-                if (DBG) log("doRecovery() cleanup all connections mPdpResetCount < max");
+            // Go through a series of recovery steps, each action transitions to the next action
+            int recoveryAction = getRecoveryAction();
+            switch (recoveryAction) {
+            case RecoveryAction.GET_DATA_CALL_LIST:
+                EventLog.writeEvent(EventLogTags.DATA_STALL_RECOVERY_GET_DATA_CALL_LIST,
+                        mSentSinceLastRecv);
+                if (DBG) log("doRecovery() get data call list");
+                mPhone.mCM.getDataCallList(obtainMessage(EVENT_DATA_STATE_CHANGED));
+                putRecoveryAction(RecoveryAction.CLEANUP);
+                break;
+            case RecoveryAction.CLEANUP:
+                EventLog.writeEvent(EventLogTags.DATA_STALL_RECOVERY_CLEANUP, mSentSinceLastRecv);
+                if (DBG) log("doRecovery() cleanup all connections");
                 cleanUpAllConnections(true, Phone.REASON_PDP_RESET);
-            } else {
-                mPdpResetCount = 0;
-                switch (mRecoveryAction) {
-                case REREGISTER:
-                    EventLog.writeEvent(EventLogTags.PDP_REREGISTER_NETWORK, mSentSinceLastRecv);
-                    if (DBG) log("doRecovery() re-register getting preferred network type");
-                    mPhone.getServiceStateTracker().reRegisterNetwork(null);
-                    mRecoveryAction = RecoveryAction.RADIO_RESTART;
-                    break;
-                case RADIO_RESTART:
-                    EventLog.writeEvent(EventLogTags.PDP_RADIO_RESET, mSentSinceLastRecv);
-                    if (DBG) log("restarting radio");
-                    mRecoveryAction = RecoveryAction.RADIO_RESET;
-                    restartRadio();
-                    break;
-                case RADIO_RESET:
-                    // This is in case radio restart has not recovered the data.
-                    // It will set an additional "gsm.radioreset" property to tell
-                    // RIL or system to take further action.
-                    // The implementation of hard reset recovery action is up to OEM product.
-                    // Once gsm.radioreset property is consumed, it is expected to set back
-                    // to false by RIL.
-                    EventLog.writeEvent(EventLogTags.PDP_RADIO_RESET, -1);
-                    if (DBG) log("restarting radio with reset indication");
-                    SystemProperties.set("gsm.radioreset", "true");
-                    // give 1 sec so property change can be notified.
-                    try {
-                        Thread.sleep(1000);
-                    } catch (InterruptedException e) {}
-                    restartRadio();
-                    break;
-                default:
-                    throw new RuntimeException("doRecovery: Invalid mRecoveryAction " +
-                        mRecoveryAction);
-                }
+                putRecoveryAction(RecoveryAction.REREGISTER);
+                break;
+            case RecoveryAction.REREGISTER:
+                EventLog.writeEvent(EventLogTags.DATA_STALL_RECOVERY_REREGISTER, mSentSinceLastRecv);
+                if (DBG) log("doRecovery() re-register");
+                mPhone.getServiceStateTracker().reRegisterNetwork(null);
+                putRecoveryAction(RecoveryAction.RADIO_RESTART);
+                break;
+            case RecoveryAction.RADIO_RESTART:
+                EventLog.writeEvent(EventLogTags.DATA_STALL_RECOVERY_RESTART, mSentSinceLastRecv);
+                if (DBG) log("restarting radio");
+                putRecoveryAction(RecoveryAction.RADIO_RESET);
+                restartRadio();
+                break;
+            case RecoveryAction.RADIO_RESET:
+                // This is in case radio restart has not recovered the data.
+                // It will set an additional "gsm.radioreset" property to tell
+                // RIL or system to take further action.
+                // The implementation of hard reset recovery action is up to OEM product.
+                // Once gsm.radioreset property is consumed, it is expected to set back
+                // to false by RIL.
+                EventLog.writeEvent(EventLogTags.DATA_STALL_RECOVERY_RESTART_WITH_PROP, -1);
+                if (DBG) log("restarting radio with gsm.radioreset to true");
+                SystemProperties.set("gsm.radioreset", "true");
+                // give 1 sec so property change can be notified.
+                try {
+                    Thread.sleep(1000);
+                } catch (InterruptedException e) {}
+                restartRadio();
+                putRecoveryAction(RecoveryAction.GET_DATA_CALL_LIST);
+                break;
+            default:
+                throw new RuntimeException("doRecovery: Invalid recoveryAction=" +
+                    recoveryAction);
             }
-        } else {
-            if (DBG) log("doRecovery(): ignore, we're not connected");
         }
     }
 
@@ -1342,119 +1373,130 @@
         SystemProperties.set("net.ppp.reset-by-timeout", String.valueOf(reset+1));
     }
 
+
+    private void updateDataStallInfo() {
+        long sent, received;
+
+        TxRxSum preTxRxSum = new TxRxSum(mDataStallTxRxSum);
+        mDataStallTxRxSum.updateTxRxSum();
+
+        if (VDBG) {
+            log("updateDataStallInfo: mDataStallTxRxSum=" + mDataStallTxRxSum +
+                    " preTxRxSum=" + preTxRxSum);
+        }
+
+        sent = mDataStallTxRxSum.txPkts - preTxRxSum.txPkts;
+        received = mDataStallTxRxSum.rxPkts - preTxRxSum.rxPkts;
+
+        if (VDBG) {
+            if (SystemProperties.getBoolean("radio.test.data.stall", false)) {
+                log("updateDataStallInfo: radio.test.data.stall true received = 0;");
+                received = 0;
+            }
+        }
+        if ( sent > 0 && received > 0 ) {
+            if (VDBG) log("updateDataStallInfo: IN/OUT");
+            mSentSinceLastRecv = 0;
+            putRecoveryAction(RecoveryAction.GET_DATA_CALL_LIST);
+        } else if (sent > 0 && received == 0) {
+            if (mPhone.getState() == Phone.State.IDLE) {
+                mSentSinceLastRecv += sent;
+            } else {
+                mSentSinceLastRecv = 0;
+            }
+            if (DBG) {
+                log("updateDataStallInfo: OUT sent=" + sent +
+                        " mSentSinceLastRecv=" + mSentSinceLastRecv);
+            }
+        } else if (sent == 0 && received > 0) {
+            if (VDBG) log("updateDataStallInfo: IN");
+            mSentSinceLastRecv = 0;
+            putRecoveryAction(RecoveryAction.GET_DATA_CALL_LIST);
+        } else {
+            if (VDBG) log("updateDataStallInfo: NONE");
+        }
+    }
+
+    @Override
+    protected void onDataStallAlarm(int tag) {
+        if (mDataStallAlarmTag != tag) {
+            if (DBG) {
+                log("onDataStallAlarm: ignore, tag=" + tag + " expecting " + mDataStallAlarmTag);
+            }
+            return;
+        }
+        updateDataStallInfo();
+
+        int hangWatchdogTrigger = Settings.Secure.getInt(mResolver,
+                Settings.Secure.PDP_WATCHDOG_TRIGGER_PACKET_COUNT,
+                NUMBER_SENT_PACKETS_OF_HANG);
+
+        if (mSentSinceLastRecv >= hangWatchdogTrigger) {
+            if (DBG) {
+                log("onDataStallAlarm: tag=" + tag + " do recovery action=" + getRecoveryAction());
+            }
+            sendMessage(obtainMessage(EVENT_DO_RECOVERY));
+        } else {
+            if (VDBG) {
+                log("onDataStallAlarm: tag=" + tag + " Sent " + String.valueOf(mSentSinceLastRecv) +
+                    " pkts since last received, < watchdogTrigger=" + hangWatchdogTrigger);
+            }
+        }
+        startDataStallAlarm();
+    }
+
+
+    private void updateDataActivity() {
+        long sent, received;
+
+        Activity newActivity;
+
+        TxRxSum preTxRxSum = new TxRxSum(mTxPkts, mRxPkts);
+        TxRxSum curTxRxSum = new TxRxSum();
+        curTxRxSum.updateTxRxSum();
+        mTxPkts = curTxRxSum.txPkts;
+        mRxPkts = curTxRxSum.rxPkts;
+
+        if (VDBG) {
+            log("updateDataActivity: curTxRxSum=" + curTxRxSum + " preTxRxSum=" + preTxRxSum);
+        }
+
+        if (mNetStatPollEnabled && (preTxRxSum.txPkts > 0 || preTxRxSum.rxPkts > 0)) {
+            sent = mTxPkts - preTxRxSum.txPkts;
+            received = mRxPkts - preTxRxSum.rxPkts;
+
+            if (VDBG) log("updateDataActivity: sent=" + sent + " received=" + received);
+            if ( sent > 0 && received > 0 ) {
+                newActivity = Activity.DATAINANDOUT;
+            } else if (sent > 0 && received == 0) {
+                newActivity = Activity.DATAOUT;
+            } else if (sent == 0 && received > 0) {
+                newActivity = Activity.DATAIN;
+            } else {
+                newActivity = Activity.NONE;
+            }
+
+            if (mActivity != newActivity && mIsScreenOn) {
+                if (VDBG) log("updateDataActivity: newActivity=" + newActivity);
+                mActivity = newActivity;
+                mPhone.notifyDataActivity();
+            }
+        }
+    }
+
     private Runnable mPollNetStat = new Runnable()
     {
-
+        @Override
         public void run() {
-            long sent, received;
-            long preTxPkts = -1, preRxPkts = -1;
+            updateDataActivity();
 
-            Activity newActivity;
-
-            preTxPkts = mTxPkts;
-            preRxPkts = mRxPkts;
-
-            long txSum = 0, rxSum = 0;
-            for (ApnContext apnContext : mApnContexts.values()) {
-                if (apnContext.getState() == State.CONNECTED) {
-                    DataConnectionAc dcac = apnContext.getDataConnectionAc();
-                    if (dcac == null) continue;
-
-                    LinkProperties linkProp = dcac.getLinkPropertiesSync();
-                    if (linkProp == null) continue;
-
-                    String iface = linkProp.getInterfaceName();
-
-                    if (iface != null) {
-                        long stats = TrafficStats.getTxPackets(iface);
-                        if (stats > 0) txSum += stats;
-                        stats = TrafficStats.getRxPackets(iface);
-                        if (stats > 0) rxSum += stats;
-                    }
-                }
-            }
-
-            mTxPkts = txSum;
-            mRxPkts = rxSum;
-
-            // log("tx " + mTxPkts + " rx " + mRxPkts);
-
-            if (mNetStatPollEnabled && (preTxPkts > 0 || preRxPkts > 0)) {
-                sent = mTxPkts - preTxPkts;
-                received = mRxPkts - preRxPkts;
-
-                if ( sent > 0 && received > 0 ) {
-                    mSentSinceLastRecv = 0;
-                    newActivity = Activity.DATAINANDOUT;
-                    mPdpResetCount = 0;
-                    mRecoveryAction = RecoveryAction.REREGISTER;
-                } else if (sent > 0 && received == 0) {
-                    if (mPhone.getState() == Phone.State.IDLE) {
-                        mSentSinceLastRecv += sent;
-                    } else {
-                        mSentSinceLastRecv = 0;
-                    }
-                    newActivity = Activity.DATAOUT;
-                } else if (sent == 0 && received > 0) {
-                    mSentSinceLastRecv = 0;
-                    newActivity = Activity.DATAIN;
-                    mPdpResetCount = 0;
-                    mRecoveryAction = RecoveryAction.REREGISTER;
-                } else if (sent == 0 && received == 0) {
-                    newActivity = Activity.NONE;
-                } else {
-                    mSentSinceLastRecv = 0;
-                    newActivity = Activity.NONE;
-                }
-
-                if (mActivity != newActivity && mIsScreenOn) {
-                    mActivity = newActivity;
-                    mPhone.notifyDataActivity();
-                }
-            }
-
-            int watchdogTrigger = Settings.Secure.getInt(mResolver,
-                    Settings.Secure.PDP_WATCHDOG_TRIGGER_PACKET_COUNT,
-                    NUMBER_SENT_PACKETS_OF_HANG);
-
-            if (mSentSinceLastRecv >= watchdogTrigger) {
-                // we already have NUMBER_SENT_PACKETS sent without ack
-                if (mNoRecvPollCount == 0) {
-                    EventLog.writeEvent(EventLogTags.PDP_RADIO_RESET_COUNTDOWN_TRIGGERED,
-                            mSentSinceLastRecv);
-                }
-
-                int noRecvPollLimit = Settings.Secure.getInt(mResolver,
-                        Settings.Secure.PDP_WATCHDOG_ERROR_POLL_COUNT, NO_RECV_POLL_LIMIT);
-
-                if (mNoRecvPollCount < noRecvPollLimit) {
-                    // It's possible the PDP context went down and we weren't notified.
-                    // Start polling the context list in an attempt to recover.
-                    if (DBG) log("Polling: no DATAIN in a while; polling PDP");
-                    mPhone.mCM.getDataCallList(obtainMessage(EVENT_DATA_STATE_CHANGED));
-
-                    mNoRecvPollCount++;
-
-                    // Slow down the poll interval to let things happen
-                    mNetStatPollPeriod = Settings.Secure.getInt(mResolver,
-                            Settings.Secure.PDP_WATCHDOG_ERROR_POLL_INTERVAL_MS,
-                            POLL_NETSTAT_SLOW_MILLIS);
-                } else {
-                    if (DBG) log("Polling: Sent " + String.valueOf(mSentSinceLastRecv) +
-                                        " pkts since last received start recovery process");
-                    mNoRecvPollCount = 0;
-                    sendMessage(obtainMessage(EVENT_START_RECOVERY));
-                }
+            if (mIsScreenOn) {
+                mNetStatPollPeriod = Settings.Secure.getInt(mResolver,
+                        Settings.Secure.PDP_WATCHDOG_POLL_INTERVAL_MS, POLL_NETSTAT_MILLIS);
             } else {
-                mNoRecvPollCount = 0;
-                if (mIsScreenOn) {
-                    mNetStatPollPeriod = Settings.Secure.getInt(mResolver,
-                            Settings.Secure.PDP_WATCHDOG_POLL_INTERVAL_MS, POLL_NETSTAT_MILLIS);
-                } else {
-                    mNetStatPollPeriod = Settings.Secure.getInt(mResolver,
-                            Settings.Secure.PDP_WATCHDOG_LONG_POLL_INTERVAL_MS,
-                            POLL_NETSTAT_SCREEN_OFF_MILLIS);
-                }
+                mNetStatPollPeriod = Settings.Secure.getInt(mResolver,
+                        Settings.Secure.PDP_WATCHDOG_LONG_POLL_INTERVAL_MS,
+                        POLL_NETSTAT_SCREEN_OFF_MILLIS);
             }
 
             if (mNetStatPollEnabled) {
@@ -1566,6 +1608,41 @@
 
     }
 
+    private void startDataStallAlarm() {
+        int delayInMs = Settings.Secure.getInt(mResolver,
+                            Settings.Secure.DATA_STALL_ALARM_DELAY_IN_MS,
+                            DATA_STALL_ALARM_DELAY_IN_MS_DEFAULT);
+        mDataStallAlarmTag += 1;
+        if (DBG) {
+            log("startDataStallAlarm: tag=" + mDataStallAlarmTag +
+                    " delay=" + (delayInMs / 1000) + "s");
+        }
+        AlarmManager am =
+            (AlarmManager) mPhone.getContext().getSystemService(Context.ALARM_SERVICE);
+
+        Intent intent = new Intent(INTENT_DATA_STALL_ALARM);
+        intent.putExtra(DATA_STALL_ALARM_TAG_EXTRA, mDataStallAlarmTag);
+        mDataStallAlarmIntent = PendingIntent.getBroadcast(mPhone.getContext(), 0, intent,
+                PendingIntent.FLAG_UPDATE_CURRENT);
+        am.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
+                SystemClock.elapsedRealtime() + delayInMs, mDataStallAlarmIntent);
+    }
+
+    private void stopDataStallAlarm() {
+        AlarmManager am =
+            (AlarmManager) mPhone.getContext().getSystemService(Context.ALARM_SERVICE);
+
+        if (DBG) {
+            log("stopDataStallAlarm: current tag=" + mDataStallAlarmTag +
+                    " mDataStallAlarmIntent=" + mDataStallAlarmIntent);
+        }
+        mDataStallAlarmTag += 1;
+        if (mDataStallAlarmIntent != null) {
+            am.cancel(mDataStallAlarmIntent);
+            mDataStallAlarmIntent = null;
+        }
+    }
+
     private void notifyNoData(GsmDataConnection.FailCause lastFailCauseCode,
                               ApnContext apnContext) {
         if (DBG) log( "notifyNoData: type=" + apnContext.getApnType());
@@ -1930,6 +2007,7 @@
         if (isConnected() && ! mPhone.getServiceStateTracker().isConcurrentVoiceAndDataAllowed()) {
             if (DBG) log("onVoiceCallStarted stop polling");
             stopNetStatPoll();
+            stopDataStallAlarm();
             notifyDataConnection(Phone.REASON_VOICE_CALL_STARTED);
         }
     }
@@ -1940,6 +2018,7 @@
         if (isConnected()) {
             if (!mPhone.getServiceStateTracker().isConcurrentVoiceAndDataAllowed()) {
                 startNetStatPoll();
+                startDataStallAlarm();
                 notifyDataConnection(Phone.REASON_VOICE_CALL_ENDED);
             } else {
                 // clean slate after call end.
@@ -2251,11 +2330,7 @@
                 onPollPdp();
                 break;
 
-            case EVENT_START_NETSTAT_POLL:
-                startNetStatPoll();
-                break;
-
-            case EVENT_START_RECOVERY:
+            case EVENT_DO_RECOVERY:
                 doRecovery();
                 break;
 
@@ -2272,6 +2347,7 @@
                  */
                 if (DBG) log("EVENT_PS_RESTRICT_ENABLED " + mIsPsRestricted);
                 stopNetStatPoll();
+                stopDataStallAlarm();
                 mIsPsRestricted = true;
                 break;
 
@@ -2284,6 +2360,7 @@
                 mIsPsRestricted  = false;
                 if (isConnected()) {
                     startNetStatPoll();
+                    startDataStallAlarm();
                 } else {
                     // TODO: Should all PDN states be checked to fail?
                     if (mState == State.FAILED) {