Just for fun, I decided to buy an old school touch tone dialer off of eBay to recondition it. In the days when rotary pulse dialing was still how most of the consumer telephony network worked, the appearance of phone tree systems (which responded to touch tones only) and remotely operable answering machines necessitated the creation of new technology - a hand-held device that generated touch tones when you pressed buttons on the keypad. The idea was that you could hold the speaker of the 'dialer up to the mouthpiece of your phone and press buttons to dial.
Phone phreaks used to modify them by switching out the timing crystal with a 6.5536 MHz crystal to turn them into red boxes. However, they stopped being useful in the mid-1990's and as such are relics of a bygone age. Which, of course, is why I added one to my trophy case.