Using C# WebService in ASP

Hi, I need to know the other ways to call web service from asp application. One of those which i know is to call asmx file from xmlhttp. with querystring as parameter but it has some limitation like we can'nt pass more than 255 kb of data from querystring. So if anyone knows please let me know as early as possible about the other methods of calligng .net web serivce from normal asp page. Thanks & regards