Input-output devices 28 may include status-indicator lights (e.g., light-emitting diodes), light-emitting diodes for providing camera flash illumination and other light, buttons, joysticks, scrolling wheels, key pads, keyboards, audio components 34 such as microphones and speakers (e.g., an ear speaker located at an upper end of device 10 and/or one or more speaker-phone speakers at an opposing lower end of device 10 or elsewhere in device 10 that are used to play audio when device 10 is being held away from a user's head), tone generators, haptic devices such as vibrators, cameras such as camera 30 (e.g., front-facing and/or rear-facing cameras), sensors 32, displays such as display 14, and other input-output components that gather input and provide output from device 10. Input-output devices 28 (e.g., sensors 32) may include touch sensors (e.g., stand-alone touch sensors for touch sensitive buttons and track pads and/or touch sensor panels that overlap display 14 and are used in gathering touch screen input from a user as selectable on-screen options are displayed on display 14). Sensors 32 may also include light sensors, orientation sensors (e.g., accelerometers, gyroscopes, compasses, and/or other components that can detect device motion and/or device orientation such as device orientation relative to the Earth), resistance sensors (e.g., sensors that can detect contact by a conductive sidewall of another device or other external object), switch-based sensors, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or a light-based proximity sensor such as an infrared proximity sensor that makes proximity sensor measurements by emitting infrared light from an infrared light-emitting diode and measuring corresponding reflected light using an infrared light detector), magnetic sensors, force sensors (e.g., force sensors based on a capacitive force sensing arrangement, strain gauges, piezoelectric force sensors, and/or other transducers that convert force into electrical signals), gas pressure sensors (e.g., sensors for measuring air pressure), gas sensors (e.g., carbon dioxide sensors), particulate sensors, moisture sensors, a connector port sensor or other sensor that determines whether first device 10 is mounted in a dock, and other sensors and input-output components.