Abstract: A microphone is provided in a mobile terminal and is connected to a current source when the flip portion of the mobile terminal is open and is disconnected from the current source when the flip portion of the phone is closed. The mobile terminal can then infer the position of the flip portion of the housing, e.g., opened or closed, based upon the state of the microphone's current supply circuit, for example by detecting the current flowing through the circuit or a voltage drop across a supply resistor. In addition, an on-hook/off-hook button can be provided to a hands-free accessory without increasing a number of signal lines/connections between the hands-free accessory and the mobile terminal. This can be accomplished, for example, by connecting the on-hook/off-hook button to a switch in the microphone signal line. The switch selectively creates an open in the microphone signal line, which can be detected by the mobile terminal, thereby resulting in an off-hook condition.

Abstract: The portable telecommunications apparatus has an audio input for receiving sound, an audio output for generating sound, a controller for controlling the audio input and the audio output, and an audio accessory interface for operatively connecting an external audio accessory. The accessory is capable of receiving external sound and forwarding it as audio signals to the apparatus and/or capable of generating external sound in response to audio signals supplied from the apparatus. The controller is arranged to receive a request for an audio service from any of at least two audio accessories operatively connected to the apparatus. The controller also has a logical state machine, the individual states of which represent possible operational conditions for the telecommunication apparatus and the audio accessories. The state machine defines how the request for audio service is to be handled each of the operational conditions.

Abstract: An electronic device operates with an external accessory by initiating a serial data communication over an accessory control bus. If data communication is established with the external accessory, the electronic device operates in a first interface mode, when one or more operating parameters are transferred over the bus. If data communication is not established, the electronic device operates in a second interface mode, when no operating parameters are transferred over the bus.