I suppose then that it all boils down to semantics. If a phone that one can use to text and take pictures is a dumb phone then what is a phone that is simply ... a phone? I think the article overstates the point by lumping phones that can send and read text (as an integral part of the phone) with phones which can only send and receive voice. Such a phone can receive a fax or a text but cannot (without modification) store and display the received data.
People bought nearly 62 million smartphones in the second quarter of 2010 (according to Gartner research). But compared to the 264 million new “dumbphones” sold in the same quarter, all those iPhones, Androids, and BlackBerrys are just a drop in the bucket.
How many of those "dumbphones" could send and display text? I would guess an overwhelming majority of them.