iPhone 4S Users Complain of Audio Bug
It’s not just the newest iPhone’s battery that’s riddled with problems. After a fix seems imminent for the battery bug, a new issue with the iPhone 4S has cropped up recently. Users have been posting on Apple’s support forums about an audio bug that ails the handsets.

According to users, they’ve been experiencing echoes during voice calls on their iPhone 4S handsets when using a wired headset. The bug isn’t there from the start, though — people notice it suddenly happening in the middle of conversations. Some experience it a few minutes in, others get a couple of hours before it happens. Also, the issue persists for any brand of headphones — even Apple-branded ones.
Apple doesn’t have a formal statement about this a particular issue yet, so I reckon an official fix isn’t very imminent. BoyGeniusReport, however, has a temporary solution for it — simply switch to speakerphone once you start hearing the echo, and then disable it quickly afterward. The echo ceases as another cycle begins; you just have to be patient enough to do over and over again if needed.
Credit: Source."Audiogate" Issue Yet to be Addressed by Apple; Users Still Have to Deal With Not Hearing Anything During Outgoing Calls
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I notice the echo from the beginning of the call and it does not normalize after switching to the speaker phone and back. It can also be recreated without using headphones by keeping the headset slightly away from your ear and talking loudly. The other person hears an echo. Really frustrating