How to record call

<?php
// Include passwords.php to get back Nusery password & login
require_once("passwords.php");
require_once("Emerginov.php");

$voice = "Zozo";
$number = $call->request['agi_callerid'];
$timestamp = "record_".$number."_".time();
$duration=60;

if (isset($_GET['stop'])) { $duration = $_GET['stop']*60;}

// Answer
$call->Answer();

// Record
$call->Record($timestamp,'wav','#',15000);

// Wait a little
sleep($duration);

// Hangup
$call->Hangup();
?>