Today, when calling my family using an Atomic Floyd Drum headset, my mother reported very bad connection quality, to the extent that we had to end the conversation as it was impossible to understand me. I found this very curious as i have always used the very same headset with my 3GS and never had any issues, neither on long calls, nor being on the same street as today.
I then remembered that i found this thread (I regularly keep track of possible issues with the devices i own).
My mother said there was no echo, but my voice was very hollow like being very far away, silent. And there were wind noises, cracking, popping, moments of interruptions. I know that there were noises in the background - but unfortunately, i will always fail to give Apple that completely silent test bed as the city around me just does not care about the iPhone requiring silence... ;-)
I took the time and did test runs. I could not reproduce an issue when calling myself from home. I finally was able to reproduce the issue by calling myself on my digital mailbox when walking to the groceries along a street with some traffic, so I have a WAV file to give to Apple support. It may be interesting that more people do recordings of this, maybe there is a pattern. (I just want to see a statement that Apple is working on it, and maybe a timeline when one can expect a solution).
It does not matter if i use the Apple headset included in the package or the Atomic Floyd Drums. All I need is some background noise to cause the problem - no matter how long the call takes. I also confirm that noises that go in the mic can be heard on the headphones very loud, a behaviour _not_ present with the very same headsets on my 3GS. If i use any of the headsets, i also have the impression that Siri does not work well (well, it never is working, or stable, or usable for that matter) when i give commands via headset. (But that is just an impression; Siri is so unreliable and has only 20% or so success that it can be easily possible that i am not testing the headset here).
On Monday, they will get a call from me as well. Regarding the above post, I made sure i shutdown and reboot the iPhone after applying 5.0.1, but i repeated today, and it definitely does not help. I will repeat the test once more with a clean installation without any software or changes to config, but given the amount of reports and the gutt feeling on the descriptions, i doubt this will make any difference. I personally suspect an issue with the automatic silencing of the mic in speech brakes, along with some distortion filtering issue. In order to support Siri, rumor has it they were adding new technology to this chain, i think its highly likely.