adding an initial Call activity

app/src/main/AndroidManifest.xml

@@ -62,6 +62,12 @@
             </intent-filter>
         </activity>
 
+        <activity
+            android:name=".activities.CallActivity"
+            android:label="@string/ongoing_call"
+            android:screenOrientation="portrait"
+            android:showOnLockScreen="true"/>
+
         <activity
             android:name=".activities.SettingsActivity"
             android:label="@string/settings"

app/src/main/kotlin/com/simplemobiletools/contacts/pro/activities/CallActivity.kt

@@ -0,0 +1,25 @@
+package com.simplemobiletools.contacts.pro.activities
+
+import android.os.Bundle
+import com.simplemobiletools.commons.extensions.checkAppSideloading
+import com.simplemobiletools.commons.extensions.updateTextColors
+import com.simplemobiletools.contacts.pro.R
+import kotlinx.android.synthetic.main.activity_call.*
+
+class CallActivity : SimpleActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        supportActionBar?.hide()
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_call)
+
+        if (checkAppSideloading()) {
+            return
+        }
+    }
+
+    override fun onResume() {
+        super.onResume()
+        updateTextColors(call_holder)
+    }
+}

app/src/main/res/layout/activity_call.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/call_holder"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+</androidx.constraintlayout.widget.ConstraintLayout>