One night when I was putting away some of my baby girl's toys, I noticed how quickly play phones seemed to have evolved over the past year. It's likely that the evolution took place over the course of several years but since I don't follow any toy blogs (which I assume would cover toy phone leaks and product launches) and my daughter is only a year old, toy phones went from what you see on the left to what you see on the right very quickly to me.
The purple toy on the left is what I consider to be representative of both a landline phone because of its shape and a cordless phone since it obviously doesn't have a cord. Then we've got the classic candy bar phone, the flip phone with stub antenna (not visible in the picture), and of course the touchscreen slab phone complete with trackball, call and end buttons, and icon grid UI.
I didn't notice this progression as each new phone was added to the toybox, particularly because they're rarely ever all together (one is usually in her bedroom, one stays in the car, etc.), but it's very obvious when they're all lined up like that.