A technique for arbitrating conflicting usage of a communications channel of a wearable communications device is disclosed. In at least one embodiment of the invention, a method includes transmitting a voice signal from a microphone to a portable device using a first communications channel in a first mode of operating a system. The method includes transmitting a monitor signal to the portable device using the first communications channel for a predetermined period of time in response to detection of a beacon signal initiated by an application executing on the portable device. The first and second signals may be ultrasonic signals received over the first communications channel and may have the same frequency and different phases. The beacon signal may be detected based on the first and second signals. The first communications channel may include an audio jack of the portable device.