Cliente NuSOAP para consumir WSDL

ConsumeSOAP.php

<?php
require_once('lib/nusoap.php');

$wsdl   = "https://pagoefectivo.pe/PagoEfectivoWSGeneralv2/service.asmx?WSDL";
$client = new nusoap_client($wsdl, 'wsdl');

// Seguridad
$username = "username";
$password = "pass";

// Si usamos json
$json     = '{"param1":"value1","param2":"value2"}';

$client->setCredentials($username, $password);
$error = $client->getError();

if ($error)
{
    echo $error; die();
}

$action = "ConsultarCIPMod1"; // Nombre del metodo

$result = array();

if (isset($action))
{
    $result['response'] = $client->call($action, $json);
}

echo "<h3>Output : </h3>";
echo $result['response'];
echo "<h2>Request</h2>";
echo "<pre>" . htmlspecialchars($client->request, ENT_QUOTES) . "</pre>";
echo "<h2>Response</h2>";
echo "<pre>" . htmlspecialchars($client->response, ENT_QUOTES) . "</pre>";