Asynchronous call timeout

[JMMB]

I'm using the following code to call different ws methods asynchronously. It
works fine.
How could I set a timeout for the asynchonous calls? I tried wait.one, but
didn't work.
thanks a lot.
private void Button1_Click(object sender, System.EventArgs e)
{
localhost.WoodgroveOnlineBank bank = new localhost.WoodgroveOnlineBank();
IAsyncResult ar = bank.BeginGetAccount(1, null, bank);
//...Do various asynchonous calls...

//...Get the results...
localhost.Acct acct = bank.EndGetAccount(ar);
Label1.Text = string.Format("The account {0} has a balance of {1:c}",
acct.description, acct.balance);
}