Adjust Proximity Sensor back to iOS6 levels for iPhone 5 My wife recently updated her iPhone 5 to iOS 7 (from iOS 6).  After the upgrade she has had issues with the proximity sensor.

It works fine when holding the phone to her ear with her hand.  However, when she tries to pinch the phone between her head and her shoulder, the proximity sensor does not see that it is near anything and she ends up dialing keys or hanging up.

Again, this only happens when trying to hold the iPhone with her shoulder.

Your response may be, "don't do that".  But she was able to do it with iOS 6 just fine, so it is kind of hard for me to tell her that.

It is only after the upgrade to iOS 7 that she started having this issue.

So my question is, can the sensitivity of the proximity sensor be adjusted? (So I can put it back to iOS 6 levels?)
No, currently there is no way to change the proximity sensor sensitivity in iOS.

There is not even any way to change it currently in iOS 6 jailbroken, so even if a jailbreak is developed for iOS 7, it would not mean that the proximity sensor could then be customised.