An upgrade (3.9.0.0) for Nokia Access Point is now available for my Lumia 925 (T-Mobile). Do I need this? In researching this, I barely understand what it is, although I do understand that it is required if I operate my phone with more than one SIM (which I don't). In researching Access Point, previous upgrades have evidently caused problems with other functions in various Nokia phones. So, again, do I need this if my 925 is operating satisfactorily?