WAP PUSH

I'm doing WAP push project URL that send to user mobile phone, when user click on it. It will immediately redirect user to download *.mid or *.jpg file.Actually I already got full working code but in PHP
PHP Code:

function returnItem($downloadItem, $file, $mimeType){
header ("Content-Type: $mimeType");
header ("Content-Disposition: attachment; filename=".basename($file).";");
header ("Content-Transfer-Encoding: binary");
@readfile($file);
} 

the most importaint part is @readfile($file) which read the file then directly output to the buffer.Can i know is there any similiar code in ASP? else pls suggest me any alternative way to solve my problem.