I'm checking the mobile traffic in a M2M web portal of our mobile provider. This is the basis for invoicing. Hence, it should be the most reliable measure. Anyway, the traffic counter of the TRB140 itself almost meets this figures. When I hit F5 to reload the home page it counts about 1 MB more in both the TRB and M2M portal. So it should come from the web page.
There is no device connected. My measures are from a test with several TRB140 devices after I realized that the traffic might come from the configuration web pages.