imagebutton gives me error: [Accessibility] Missing contentDescription attribute on image

Designing for Accessibility

"Defines text that briefly describes content of the view. This property is used primarily for accessibility. Since some views do not have textual representation this attribute can be used for providing such."

And this is not error just a warning. Usage of this attribute is optional.

Add to the imageButton

android:contentDescription="@string/desc"

Just add this:

android:contentDescription="@string/description"

then go to yours Strings.xml and add this:

<string name="description"> YOUR_DESCRIPTION_HERE </string>

as of your code:

<ImageButton
    android:id="@+id/callbannerbuttonpg1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="157dp"
    android:background="@null"
    android:src="@drawable/callbanner"
    android:visibility="invisible"
    android:contentDescription="@string/description" />