Contacts/app/src/main/res/layout/activity_dialpad.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/dialpad_wrapper"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.constraint.ConstraintLayout
        android:id="@+id/dialpad_holder"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="@dimen/activity_margin"
        android:layout_marginLeft="@dimen/activity_margin"
        android:layout_marginRight="@dimen/activity_margin">

        <com.simplemobiletools.commons.views.MyEditText
            android:id="@+id/dialpad_input"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:inputType="phone"
            android:textCursorDrawable="@null"
            android:textSize="@dimen/dialpad_input_text_size"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_2"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_1"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="1"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_4"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_2"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="parent"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_2"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="2"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_5"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_3"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_1"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_3"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="3"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_6"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_2"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_4"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="4"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_7"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_5"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="parent"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_5"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="5"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_8"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_6"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_4"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_6"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="6"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_9"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_5"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_7"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="7"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_asterisk"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_8"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="parent"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_8"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="8"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_0"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_7"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_9"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="9"
            app:layout_constraintBottom_toTopOf="@+id/dialpad_hashtag"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_8"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_asterisk"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="*"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_0"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="parent"
            tools:layout_editor_absoluteY="0dp"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_0"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="0"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toStartOf="@+id/dialpad_hashtag"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_asterisk"/>

        <com.simplemobiletools.commons.views.MyTextView
            android:id="@+id/dialpad_hashtag"
            style="@style/DialpadNumberStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="#"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/dialpad_0"/>

    </android.support.constraint.ConstraintLayout>
</RelativeLayout>