Hello all. I was having the same audio problems and came upon this forum last Friday night, when I realized that I was not going crazy and there was a problem. I had a 16 gb 4s on AT&T. I called Apple and they wanted to send a replacement. They told me it was going to be a new one; but it came in the small white box, not a retail box, so it was a reconditioned. In which ended up having a light 1 inch scratch on the screen. I was not happy, considering I was adamant that I wanted a brand new one (I only had the phone 7 days at the time), and promptly called them and told them they were getting their scratched recon back. Made an appointment at the Apple store and got an exchange there. They would not give me a new one. Well, I inspected it pretty good there, but found a very tiny chip on the front glass at the seam on top when I got home. Very hard to see, but I was not going to accept it. Got lucky and was able to return it for a full refund. I will use my old phone until further notice.
I was able to test both replacements, however. On the first replacement, I set up as new phone and made approx. 25 calls and could not get it to fail. Restored from backup, did everything as I did with original, made approx. 50 calls and could not get it to fail (but it had the scratch). Second replacement started having the audio issue after I noticed the chip on the glass, but was much more intermittent than the original. I was able to reproduce the problem on the original for the Apple genius on the first try. That's pretty bad.
I, along with some of you, am going to wait it out and see what happens. Hopefully the issue will be publicly addressed, although I'm doubting it. I don't think that I will buy an iphone if the problem is not publicly addressed. I refuse to get a recon phone that may have a scratch, chip, or whatever when I'm handing them an absolutely flawless 7 day old phone. Obviously, the recons are not always "like new", as they try to tell you. If they replace the front glass every time (that's what they told me, but I don't believe them), then someone is botching them up when they replace them.
I think it's ridiculous that once you leave the store, you are left getting a recon if you have problems. I feel that if it's 30 days, or less, that it should be replaced with a new one. I mean, come on, I can return my phone for a full refund, but if I get a replacement your going to hand me a recon that might be botched up? If 2 out of 2 recons were botched up, then odds are that a lot of them are. To make matters even worse, one was shipped from PA and the other came from the store in FL. That makes the odds even worse. Now, I will admit that I'm a perfectionist and will notice any flaw under the correct lighting, but the point is that my original had no flaws and that's what I want back. One of the first things that I do is put a front and rear screen shield on and put it into a nice rubbery case, so that it stays nice a new and retains it's resale value. If I get one with cosmetic imperfections, then that defeats the purpose.
Well, that's my story and I'm sticking to it. Good luck to everybody.