UPDATE: It appears that users who have reported resolution to this issue with the iOS 4.0.1 update may be experiencing improvement simply due to the restore and reset processes that occur during any iOS update, as Apple has now said that a permanent fix for the proximity sensor issue is coming in iOS 4.1 — due later this month.
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It appears that iOS 4.0.1 resolves for many users 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.
Although some users still report the problem, a number of posters to Apple’s Discussion Boards note significant improvement:
- zoogme: “4.0.1 has fixed my sensor. It seems to be very snappy. It activates and deactivates very fast after the new firmware. I will have to also test out with the wife’s iPhone4.”
- Bryann: “My proximity sensor issues seems to be fixed as well!”
- bcfc789: “My sensor issues seemed to be fixed as well i have made 3 calls after update and no issues.”
If you are still experiencing this issue, see our previously mentioned fixes.