C# - JavaScript PageMethods Call Loosing HttpContext.Current State?

I am using JavaScript's PageMethod functionality where I am invoking a PageMethod which works like a gem. However I am having an issue in accessing the HttpContext's state which returns me a value "SYSTEM" for

HttpContext.Current.User.Identity.Name

which is not the actual current User Name.

I know there are couple options like storing HttpContext.Current in a Session or saving Context's state in some other custom container but given a web farm environment I am assuming that this will not work as expected.

Here is the code I am working on with

function MyFunction(){
PageMethod.MyPageMethod();
}

here is the signature of the server method

[System.Web.Services.WebMethod()]
public static void MyPageMethod()
{
// gives me "SYSTEM"
var user = HttpContext.Current.User.Identity.Name;
}

Also if I use the above code to access user name in OnLoad event of the page then it works fine and returns me the CurrentUserName.

I am trying to get the above code to work in an ASP.NET Webform... :)

So I am wondering if there is a way to access the current actual user in page methods without making use of sessions.