A touch-tone phone, also known as a push-button phone, refers to a telecommunications device that uses a set of buttons or keys to dial numbers. Other synonyms for this device include a digit dial phone, keypad phone, and touch keypad phone. Previously, rotary dial phones were commonly used, but touch-tone phones replaced them as they were more efficient and faster to use. The technology has since evolved, and we now have smartphones, which are touch-tone phones but with added features such as touchscreens and advanced software. Overall, a touch-tone phone is a convenient and reliable way to communicate with others, and its synonyms provide a wider range of options to refer to it.