A button phone is a type of telephone that has physical buttons for dialing numbers. It is also known as a rotary phone due to the rotary dial used to enter the numbers. The term 'button phone' is often used to refer to older models of telephones, but modern versions of the button phone are still available. The term 'HOLD' is an acronym for 'Hang On Line Dial, ' which is a feature of button phones that allows the user to place a call on HOLD while they make another call.