The iPhone 4 had one of the cheekiest glitches to hit the smartphone.

Every iPhone since the original has come equipped with a proximity sensor that detects when you put the phone to your ear. In theory, when you use the iPhone as a phone, the screen shuts off so that you don't accidentally select any of the on-screen options that could disrupt a call, like "mute," "hold" or "end."

But iPhone 4 users complained that the sensor in the iPhone 4 didn't work properly, causing the device to accidentally drop calls or dial numbers mid-conversation.

After thousands of commenters posted to Apple's forums, the company fixed the issue with a software upgrade.

Last updated November 03 2011: 2:32 PM ET
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