Adding phone number field to existing contact form

This is my send.php

$to ="; //Your email goes here

$name = stripslashes($_POST["name"]);
$email = stripslashes($_POST["email"]);
$subject = stripslashes($_POST["name"]);
$message = stripslashes($_POST["message"]); 

$headers  = "MIME-Version: 1.0" . "\\r\
$headers .= "Content-type: text/plain; charset=utf-8" . "\\r\
$headers .= "From: $name <$email>" . "\\r\

if(mail($to, $subject, $message, $headers)){
	echo "Your message was sent! Thank you."; //This message gets display to user on success
	echo "Sorry, your message wasn't sent. Try again or contact me at $to"; //Message displayed to user on failure

and this is my contact form.

  <h1 class="header">Contact form</h1>
        <form id="contact-form" action="">
            <label for="form_name">Name</label>
            <input id="form_name" name="name" type="text" /><br />
            <label for="form_email">Email</label>
            <input class="vemail" id="form_email" name="email" type="text" /><br />
            <label for="phone">Phone #</label>
            <input class="phone" id="phone" name="phone" type="text" /><br />
            <label for="form_message"></label>Comment<br /><br />
            <textarea id="form_message" name="message" rows="5" cols="10"></textarea><br />
            <input id="send_contact" type="image" src="images/submit.png" />

This contact form is working fine, it sends to my email address, but I need to include the phone number in the body of the email. I know i added the phone number field alreaday. But I need help getting it on send.php
Can someone help please.

add this

$phone_number = isset($_POST["phone"]) ? stripslashes($_POST["phone"]) : '';
$message .= "\
" . $phone_number;


$message = stripslashes($_POST["message"]); 

you have all the option now on how you would like to format the message or just leave it like what I did, put it at the bottom of the $message