Fluid Grid/Responsive Design in DW CC Q?

Hey guys..

Im trying to learn the above statement.. Im puzzled about one part (mobile settings).....

These are the hottest selling phones in Australia this year..

- HTC One (M8) 1920x1080 display

- Xperia Z2 1920x1080 resolution screen

- Galaxy S5 1080 x 1920 pixels

DW fluid grid default settings

I get Desktop:1232px

I get Tablet:768px

I DONT get Mobile:480px ???

My question is.. These new resolutions are bigger than my desktop?.. Does the mean a page will display even smaller than on desktops?... As they are no where near 480px does that mean the DW mobile setting will never be activated therefore useless?.. what impact do these new sizes have on "Viewport scale=1"... (Im thinking scale x 4 and responsive?)

Would be grateful if someone could clear my confusion?

ty