Android : Calling an ayncTask and getting static related error

I am calling php script which accesses my db from an android lass. The class is below;

public class pk_http {

    // Progress Dialog
    private ProgressDialog qDialog;

    // JSON parser class
    JSONParser jParser = new JSONParser();

    class phpCall extends AsyncTask<String, String, String> {
        @Override
        protected String doInBackground(String... args) {
            // Building Parameters
            String url = args[0];
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            // getting JSON string from URL
            JSONObject json = jParser.makeHttpRequest(url, "GET",params);



            return null;
        }
   }

Now when i call that from my calling class (the calling class does not extend Activity btw) this way;

public static ArrayList<String> getLoginTileDataArray(Context c)
{
    //CODE STUB: HTTP GET RETURNS THE FOLLOWING STRING
    String result = pk_http.phpCall.execute("http://myUrl/phpFile.php");
.
.
.

I have a error pre-compilation that says;

Non-static method 'execute(Params...) cannot be referenced from a static context.

if i remove the 'sttic' no change. Am i calling the async method correctly?