How to center a textview inside a linearlayout

set the gravity to center in your linearLayout tag :

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
     android:gravity="center"
    android:background="@drawable/carefreebgscaledalphajpg" >

or use a RelativeLayout like this :

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/carefreebgscaledalphajpg" >



    <TextView
        android:id="@+id/textviewdatefornocallspage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="You have no calls for "
        android:textSize="25sp" />

</RelativeLayout>