$wsdl = 'http://<machineip>:48620/Metadata/Legacy/Full/DynamicsGP.wsdl';
        $trace = true;
        $exceptions = false;
        $aHTTP['http']['header'] =  "User-Agent: PHP-SOAP/5.5.11\r\n";
        $aHTTP['http']['header'].= "username: user\r\n"."password: pass\r\n";
        $context = stream_context_create($aHTTP);

        $xml_array['PONUMBER'] = '2725865';

        $client = new SoapClient($wsdl, array('trace' => $trace, 'exceptions' => $exceptions, 'stream_context' => $context));
        $response = $client->GetPurchaseOrderByKey($xml_array);

        dd($response);