Error 405 when consuming Web Service

This is my code:

<?php    
    require_once("../nusoap-0.9.5/lib/nusoap.php");

    $wsdl = 'http://url';

    $client = 
    new nusoap_client

    ($wsdl, array( 'soap_version' => SOAP_1_1,
        'trace' => true)); 

    $err = $client->getError();

    if ($err) 
    {   
        echo 'Error en Constructor' . $err ; 
    }

    $params = array();
    $params['requestIP'] = 'ip del vpn';
    $params['transactionDate'] = date('dmYHis');
    $hash = hash('sha256', implode('$$', $params));
    $params['transactionHash'] = $hash;
    $result = $client->call( 'getIdentificationTypes',$params);

    if ($client->fault) {
        echo 'Fallo la conexion';
    } 
    else {  // Chequea errores
        $err = $client->getError();
        if ($err) {     // Muestra el error
            echo 'Error EN ' . $err ;
        } else {        // Muestra el resultado
            echo 'El Resultado es';
            print_r ($result);
        }
    }
?>

And this error is generated:

HTTP ERROR: Unsupported HTTP response status 405 Method Not Allowed (soapclient->response has contents of the response)

Any ideas on how I can solve the problem?