$xml = '<?xml version="1.0" encoding="utf-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:envgen="http://soapenvelopegenerator.eduardocastro.info/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">'
.'<soapenv:Header />'
.'<soapenv:Body>'
.'<S_AUTHENTICATE_V002Request xmlns="http://www.gubse.com/IFS/SihotServices01.xsd">'
.'<TransactionID></TransactionID>'
.'<AuthenticationInfos>'
.'<user>'.$this->user_name.'</user>'
.'<password>'.$this->pass.'</password>'
.'<hotel>1</hotel>'
.'<hoteldate></hoteldate>'
.'<useldap></useldap>'
.'<product></product>'
.' </AuthenticationInfos>'
.'</S_AUTHENTICATE_V002Request>'
.'</soapenv:Body>'
.'</soapenv:Envelope>';


$ch = curl_init();
curl_setopt( $ch, CURLOPT_URL, $this->url );
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, 1 );
curl_setopt( $ch, CURLOPT_POST, 1 );
curl_setopt( $ch, CURLOPT_POSTFIELDS, $xml );
curl_setopt( $ch, CURLOPT_HTTPHEADER,
[
"Content-Type: text/xml; charset=UTF-8"
]
);
$output = curl_exec( $ch );
return $output;

Gibi.