diff --git a/app/InCallService/Android.bp b/app/InCallService/Android.bp
new file mode 100644
index 0000000..649bdc0
--- /dev/null
+++ b/app/InCallService/Android.bp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2022 bengris32
+ * Copyright (C) 2022 LineageOS
+ *
+ * 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.
+ */
+
+android_app {
+    name: "MtkInCallService",
+
+    srcs: ["src/**/*.java"],
+    resource_dirs: ["res"],
+
+    certificate: "platform",
+    platform_apis: true,
+    privileged: true,
+
+    optimize: {
+        enabled: false,
+    }
+}
diff --git a/app/InCallService/AndroidManifest.xml b/app/InCallService/AndroidManifest.xml
new file mode 100644
index 0000000..cb5c2bc
--- /dev/null
+++ b/app/InCallService/AndroidManifest.xml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="org.lineageos.mediatek.incallservice"
+    android:versionCode="1"
+    android:versionName="1.0"
+    android:sharedUserId="android.uid.system">
+
+    <application
+        android:label="@string/app_name"
+        android:persistent="true">
+        <receiver
+            android:directBootAware="true"
+            android:exported="true"    
+            android:name="org.lineageos.mediatek.incallservice.OnLockedBootCompleteReceiver">
+            <intent-filter>
+                <action android:name="android.intent.action.LOCKED_BOOT_COMPLETED" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </receiver>
+        <service
+            android:directBootAware="true"
+            android:name="org.lineageos.mediatek.incallservice.VolumeChangeService">
+        </service>
+    </application>
+</manifest>
diff --git a/app/InCallService/res/values/strings.xml b/app/InCallService/res/values/strings.xml
new file mode 100644
index 0000000..2be002f
--- /dev/null
+++ b/app/InCallService/res/values/strings.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_name">Mediatek In-Call Service</string>
+</resources>
diff --git a/app/InCallService/src/org/lineageos/mediatek/incallservice/OnLockedBootCompleteReceiver.java b/app/InCallService/src/org/lineageos/mediatek/incallservice/OnLockedBootCompleteReceiver.java
new file mode 100644
index 0000000..218f437
--- /dev/null
+++ b/app/InCallService/src/org/lineageos/mediatek/incallservice/OnLockedBootCompleteReceiver.java
@@ -0,0 +1,19 @@
+package org.lineageos.mediatek.incallservice;
+
+import android.content.BroadcastReceiver;
+import android.content.Intent;
+import android.content.Context;
+
+import android.util.Log;
+
+public class OnLockedBootCompleteReceiver extends BroadcastReceiver {
+    private static final String LOG_TAG = "MediatekInCallService";
+
+    @Override
+    public void onReceive(final Context context, Intent intent) {
+        Log.i(LOG_TAG, "onBoot");
+
+        Intent sIntent = new Intent(context, VolumeChangeService.class);
+        context.startService(sIntent);
+    }
+}
diff --git a/app/InCallService/src/org/lineageos/mediatek/incallservice/VolumeChangeReceiver.java b/app/InCallService/src/org/lineageos/mediatek/incallservice/VolumeChangeReceiver.java
new file mode 100644
index 0000000..b95fb01
--- /dev/null
+++ b/app/InCallService/src/org/lineageos/mediatek/incallservice/VolumeChangeReceiver.java
@@ -0,0 +1,50 @@
+package org.lineageos.mediatek.incallservice;
+
+import android.content.Intent;
+import android.content.Context;
+import android.content.BroadcastReceiver;
+
+import android.media.AudioManager;
+import android.media.AudioSystem;
+import android.media.AudioDeviceInfo;
+
+import android.util.Log;
+
+public class VolumeChangeReceiver extends BroadcastReceiver {
+    public static final String LOG_TAG = "MediatekInCallService";
+
+    private AudioManager mAudioManager;
+
+    public VolumeChangeReceiver(Context context) {
+        mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+    }
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        int streamType = intent.getIntExtra(AudioManager.EXTRA_VOLUME_STREAM_TYPE, -1);
+        if (streamType == AudioSystem.STREAM_VOICE_CALL) {
+            AudioDeviceInfo callDevice = mAudioManager.getCommunicationDevice();
+            if (callDevice.getInternalType() != AudioDeviceInfo.TYPE_BUILTIN_EARPIECE) {
+                // Device is not the built in earpiece, we don't need to do anything.
+                return;
+            }
+
+            // Start building parameters
+            String parameters = "volumeDevice=" + (callDevice.getId() - 1) + ";";
+            int volumeIndex = intent.getIntExtra(AudioManager.EXTRA_VOLUME_STREAM_VALUE, -1);
+            if (volumeIndex < 0) {
+                Log.w(LOG_TAG, "Could not get volumeIndex!");
+                return;
+            }
+
+            // Limit volumeIndex to a max of 7 since that's the size of
+            // MediaTek's gain table.
+            parameters += "volumeIndex=" + Math.min(7, volumeIndex) + ";";
+            parameters += "volumeStreamType=" + streamType;
+
+            // Set gain parameters
+            Log.d(LOG_TAG, "Setting audio parameters: " + parameters);
+            AudioSystem.setParameters(parameters);
+        }
+    }
+}
diff --git a/app/InCallService/src/org/lineageos/mediatek/incallservice/VolumeChangeService.java b/app/InCallService/src/org/lineageos/mediatek/incallservice/VolumeChangeService.java
new file mode 100644
index 0000000..e15f47f
--- /dev/null
+++ b/app/InCallService/src/org/lineageos/mediatek/incallservice/VolumeChangeService.java
@@ -0,0 +1,39 @@
+package org.lineageos.mediatek.incallservice;
+
+import android.media.AudioManager;
+
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.Context;
+import android.app.Service;
+import android.os.IBinder;
+
+import android.util.Log;
+
+public class VolumeChangeService extends Service {
+    public static final String LOG_TAG = "MediatekInCallService";
+
+    private Context mContext;
+    private VolumeChangeReceiver mVolumeChangeReceiver;
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        return null;
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+    }
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startid) {
+        mContext = this;
+        mVolumeChangeReceiver = new VolumeChangeReceiver(mContext);
+
+        Log.i(LOG_TAG, "Service is starting...");
+        this.registerReceiver(mVolumeChangeReceiver,
+                               new IntentFilter(AudioManager.VOLUME_CHANGED_ACTION));
+        return START_STICKY;
+    }
+}
diff --git a/device.mk b/device.mk
index 5bd516b..1f5d8a3 100644
--- a/device.mk
+++ b/device.mk
@@ -58,6 +58,9 @@ PRODUCT_PACKAGES += \
     libtinyxml \
     tinymix
 
+PRODUCT_PACKAGES += \
+    MtkInCallService
+
 PRODUCT_COPY_FILES += \
     $(LOCAL_PATH)/configs/audio/audio_device.xml:$(TARGET_COPY_OUT_VENDOR)/etc/audio_device.xml \
     $(LOCAL_PATH)/configs/audio/audio_effects.xml:$(TARGET_COPY_OUT_VENDOR)/etc/audio_effects.xml \