An adapter apparatus for coupling a headset and an audio device to a telephone headset amplifier includes a first interface for sending and receiving audio signals with the telephone headset amplifier, a second interface for sending and receiving audio signals with the headset, a third interface for sending receiving audio signals with the audio device, and a switching circuit coupled to the three interfaces, wherein the switching circuit provides a communications link between at least two of the first interface, the second interface, and the third interface as a function of a selected mode. In a first mode, a communications link between the second interface and the third interface is established where the audio device either provides audio signals to or receives audio signals from the headset. In a second mode, a communications link between the first interface, the second interface, and the third interface is established where the audio device receives audio signals from the headset and from the telephone headset amplifier over the communications link. In a third mode, a communications link between the first interface, the second interface, and the third interface is established where the audio device provides audio signals to the headset and to the telephone headset amplifier over the communications link.