PHP

PHP: Hypertext Preprocessor is a programming language commonly used for server-side processing in web applications. It was designed to be embedded into HTML, making it a useful tool for the production of dynamic web pages. Similarly, it can also be embedded into VoiceXML to produce dynamic callflows.

PHP was created by Rasmus Lerdorf in 1995 and has been in development by volunteers around the world ever since. While it can perform complex back-end tasks -- for example, the Facebook site is written in PHP -- it is loosely typed and generally considered easier to learn than languages like C++ and Java.

The following is one of many examples from the Plum documentation:

<?php
header("Content-type: text/xml");
echo("<?xml version=\"1.0\"?>\n");
$customerid = $_GET['customerid'];
$age = $_GET['age'];

function esc($val) {
  return htmlspecialchars($val);
}
?>

<vxml version="2.0">
  <form>
    <block>
      <prompt>
        Your customer identification number is <?php echo(esc($customerid))?>.
      </prompt>
      <prompt>
        Your age is <?php echo(esc($age))?>.
      </prompt>
    </block>
  </form>
</vxml>

PHP is documented in detail online at php.net.