iPhone 4s, echo when using apple headset during a call
I'm having an issue with my 32 gb iPhone 4s with Rogers. When using the Apple hands free headset with the phone during a call, I get an echo problem. It does not occur immediately. It can very from 30 seconds into a call and as far up to 9 mins in before it begins the annoying echo. If I unplug the headset it goes away but will return when I plug the headset back in. I have tried 3 brand new iphone 4s headsets with the same problems. So far I have tried rebooting, and also restored phone back to factory original settings as a new phone and still no resolution. I have been told by the other person on the line a screech sound is made then the echo begins.
iPhone 4s-OTHER, iOS 5, iPhone 4s