Meaning of PUSHBUTTON DIALING in English

Dialing in which (a) pushbuttons or keys are used to actuate and connect audible tone oscillators to a line , (b) each button or key corresponds to a unique frequency or set of frequencies, and (c) each pushbutton or key represents a unique digit or symbol. [ From Weik '89 ]

Telecommunication standard terms English vocab.      Английский словарь стандартных телекоммуникационных терминов.