I did order this bed thru my phone. When I purchased, it said the mattress- included. I thought this is great deal for the frame and mattress together. When I got the bed, the mattress was not delivered, and I was informed that the mattress supporsed to not included. 
So, I figured it out myself, the truth is their mobile version has different info about this item. Even now, the customer service people say they only see the mattress is not included. I called them and emailed them to talk about this, but I feel they don't pay attention to the fact. wayfair.com may have good items to buy, but the way they treat their customer, at least to me, was very disappointing.