The phone I had before my first smartphone, a Motorola Razr V3, was 2.1 × 3.9 × 0.54 inches
I remember thinking that my first smartphone, the iPhone 4s, was enormous at 4.54 × 2.31 × 0.37 inches.
The current iPhone is 5.81 × 2.82 × 0.31 inches.
But at least the least important dimension keeps getting fractionally smaller I guess?