How to call async web service in Windows Phone

how do I call asynchronous web service in Windows Phone??

I have added service reference that contains URL like "xxxxxxxxxxxxx.wsdl"

now, I am getting all web methods that are created in that URL, for example

m1234

m2378

now, how do I code??

i have created 50 percent, but stuck here,

see my code: dont know, in method that I have created, which should I do??

ServiceReference2.CommonWSEndPointClient cli = new CommonWSEndPointClient();

            cli.m291520Async();
            cli.m291520Completed += new EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(cli_m1234Completed);

 void cli_m1234Completed(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
        {
}