Consuming WebService from ASP.NET

Question

All,

I developed ftpwebsiteto download and  upload in ftp machine,

for this i developed a WCF which has core functions ( download & upload),and it will be deployed in our server machines.

i have ASP.NET website ,from this i m calling the method , i m using async methods , whenever i hit callback method i will get status for that operation.

How do i get back these values from WCF  to Website ??  because when i click download async that site lose its control over and returns ,