Here is the php mail function page:
http://php.net/manual/en/function.mail.php
You cannot add the phone number inside the function like that.
Here is the basic function:
mail(email,subject,body);
You need to add the phone number to the body of the text:
$email = "contact@jeremyblaze.com";
$subject = "Contact Form: ".$_POST['name'];
$body = "From: ".$_POST['email']."\n\r\n\rPhone: ".$_POST['phone']."\n\r\n\r".$_POST['text'];
mail($email,$subject,$body);
You should really look at the documentation on the php site:
http://php.net/manual/en/function.mail.php
It will show you how to set additional headers for reply-to and from, etc. But what I gave you should make what you are trying to do.