The iPhone did it by being essentially an iPod Touch that could make calls. Lots of people were already familiar with iPod and iPod Touch, so when it turned into the first programmable phone, it was novel and exciting, and then the gold rush took off when people started making money and it grew from there.
Yeah it was "essentially" a mobile phone that people already understood the value of, particularly because of Blackberry, so it was a potentially improved mobile phone given its touchscreen and interface. It was also a much better iPod and a web browser alongside. The iPod touch came much later.
