AT&T iPhone issue question?

[Texastaxi]

My 4, with an otterbox does it too.
One day I finally looked at the phone, right before I was going to toss it out the window, and the mute button was blue!

[cosmiccowboy]

Probably not the issue here but we have had similar problems in the past with cell phones I issue to my employees...found out that tiny metal dust in the air from welding/grinding was attracted to the magnet on the microphone and eventually make it not work properly...they would go back to work after the mic was cleaned.

[Mary]

This happens to my wife's iPhone 4. Yes, it's in an Otterbox.

I had one on my 4, I kept having problems, went to Apple, and they determined it was the Otterbox. It was messing with the proximity sensor. It is something that Otterbox now knows about and has fixed the design problem.

If she has had the Otterbox a while, call them. They sent me a new one after my call, and it fixed the issue

[wtx223]

Mute button on screen. Screen will go black when talking, but when phone is moved during conversation, screen lights up and mute button is being hit with cheek.

[Gladesgator]

Mine would not lock the screen during a call and my cheek would hit the mute button or the facetime button etc. The proximity sensor located near the top front of the phone would not work properly in an Otterbox, I cut the small piece of clear plastic out of the Otterbox case that was over the proximity sensor, no more problems.

[Tx Cazador]

Reset Network settings sometimes works