Sample code on how to take an SMS and respond with an SMS based on what the person sent in

handle-incoming-sms.php

<?php
	header('Content-type: text/xml');
	echo '<?xml version="1.0" encoding="UTF-8"?>';
?>
<Response>
	<?php
		// When an SMS comes into your Twilio phone number, Twilio passes
		// the body of the SMS to your web app in the Body parameter.
		$keyword = strtolower(trim($_REQUEST['Body']));

		switch ($keyword)
		{
			case 'hi':
				$reply = 'Hello there!';
				break;

			case 'are you a human?':
				$reply = 'Of course I am!';
				break;

			case 'oh yeah? prove it!':
				$reply = 'Uh...how would I do that?';
				break;

			// And so on

			default:
				$reply = 'Sorry what was that?';
		}

		echo "<Sms>$reply</Sms>";
	?>
</Response>