Users continue to experience an issue in which the iPhone 4 unexpectedly mutes a call, hangs up or engages FaceTime when the device is held up to the ear. This problem occurs due to apparent under-sensitivity of the iPhone 4′s proximity sensor, which turns off the screen (and touch capabilities) when the phone is held to the ear. In other words, the proximity sensor does not properly engage, and the user’s cheek or ear accidentally touches the mute button or other functions. In other cases, it appears that the proximity sensor is not engaging at all, leaving the screen on and touchable while the iPhone 4 is held to the ear.
We’ve noted a number of potential fixes for this issue, one of which involves opening another app right after making or receiving a phone call that won’t invoke any unwanted functions if accidentally tapped.
An iOS developer has now developed an app dubbed Call Guard expressly for this purpose. Call Guard “prevents accidental user input while on a phone call, putting an end to accidental hang-ups, mutes, speakerphones, etc.” by simply offering a blank interface that will not perform any action when touched. A new version of the app tracks and displays touches, “showing you how many touches (and where) have been registered by Call Guard.”
There remains controversy over whether the forthcoming iOS 4.1 release will resolve this issue, but Call Guard provides a workable, albeit somewhat clunky solution in the meantime.