Hello,
now I'm about to join this thread "in person" after following it for a while.
To Lookman1964: I just tried your tipp about enabling mobile data, then rebooting. For me it didn't work.
Still the same problem as so often described in this thread: Nearly always when trying to make a call I don't get an audio, while the called can hear me without problems. When being called myself, I have no problems.
Most of the time the trick with activating the speaker and then deactivating it again works and I can make a successful call. But not always. Today was a day where nothing seemed to work.
If you need to make an important call and it doesn't work it's really frustrating!
I have already been to an Apple Store once, where I got the information, that the issue was known and that an IOS-Update is about to be released that fixes the issue. That was supposed to be available at the end of February (I live in Germany, so please excuse any language errors). Now it's March and no Update came around yet. And what's worse: After checking this post again it seems to me, that the new Update 5.1 doesn't seem to fix the problem.
It looks like I too need to get my phone replaced, which is annoying, because I can't use my old smartphone with the Micro-SIM and I don't want to be without a phone while waiting for the new one.
Well it's just one more unhappy iPhone 4S user, but I had higher expectations when finally getting my first iPhone.
I must say my old Samsung Android didn't disappoint nearly as much for not even half the price.