Constant contact integrate using CURL

<?php

//Constant Contact//

$emailaddress = trim("email");

/////////// REGISTER EMAIL WITH CONSTANT CONTACT ///////////////////

$UN = "un";

$PW = "pw";

$Key = "api";

$entry = '<entry xmlns="http://www.w3.org/2005/Atom">

<title type="text"> </title>

<updated>' . date('c') . '</updated>

<author></author>

<id>data:,none</id>

<summary type="text">Contact</summary>

<content type="application/vnd.ctct+xml">

<Contact xmlns="http://ws.constantcontact.com/ns/1.0/">

<EmailAddress>' . $emailaddress . '</EmailAddress>

<OptInSource>ACTION_BY_CUSTOMER</OptInSource>

<ContactLists>

<ContactList id="http://api.constantcontact.com/ws/customers/' . $UN . '/lists/1" />' // Do this for all the lists you want to add to

. '

</ContactLists>

</Contact>

</content>

</entry>';

// Initialize the cURL session

$request ="https://api.constantcontact.com/ws/customers/" . $UN . "/contacts";

$session = curl_init($request);

// Set up digest authentication

$userNamePassword = $Key . '%' . $UN . ':' . $PW ;

// Set cURL options

curl_setopt($session, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);

curl_setopt($session, CURLOPT_USERPWD, $userNamePassword);

curl_setopt($session, CURLOPT_POST, 1);

curl_setopt($session, CURLOPT_POSTFIELDS , $entry);

curl_setopt($session, CURLOPT_HTTPHEADER, Array("Content-Type:application/atom+xml"));

curl_setopt($session, CURLOPT_HEADER, false); // Do not return headers

curl_setopt($session, CURLOPT_RETURNTRANSFER, 1); // If you set this to 0, it will take you to a page with the http response

// Execute cURL session and close it

$response = curl_exec($session);

curl_close($session);

?>