yes, the phone number should be returned and saved to a session named:
<?php echo ((isset($_SESSION["eCartCheckoutForm_phone"]))?$_SESSION["eCartCheckoutForm_phone"]:"") ?>
HINT: if you want to see a listing of all sessions that are set, use the following code:
<pre><?php @session_start(); var_dump($_SESSION); ?></pre>
that will write all sessions to the page, including the name and value, you can use that to find the session name for a particular variable.