Hi all, just got a new basic mobile, all I need. On opening it to insert my card there are 2 slots (bays). I have put mine into one and it works fine but what is the other one for, there is no reference to it in the manual and looking on line the images I have found only show one. It is TTfone VenusTT700. Browsing the web I can find some mentions of this but nothing at all clear.