designating or of a type of telephone that may be used with a service () that responds to individual fixed electronic tones activated by corresponding buttons pushed in placing a call
See touch-tone in American Heritage Dictionary 4
also touch·tone(tŭchˈtōnˌ)
adjective
Of, relating to, or being a telephone with which the user places calls by pressing pushbuttons that generate and transmit tones of differing pitch, these tones corresponding to the digits of the number being called.