def execute_call_xml(url)
			doc = REXML::Document.new(execute_call_plain(url))
			raise create_error(doc) unless doc.elements["rsp"].attributes["stat"] == "ok"
			doc
		end
def execute_call_xml(url)
			doc = REXML::Document.new(execute_call_plain(url))
			raise create_error(doc) unless doc.elements["rsp"].attributes["stat"] == "ok"
			doc
		end
Get plain response body and parse the XML doc