I have an iphone 4, my mom has a 3G. Every once in a while, since we both updated to 4.1, when we first make a call and the other person answers, it sounds like there is a helicopter in the background. (my moms description) The voice of the other person breaks up every other second. I can't hear them and they can't hear me correctly. It happens to my mom too. We both have a case on our phones, and this didn't start until after the update. Anyone else have a similar problem?