Static in the back while on call.

Others have definitely experienced this:

http://forums.macrumors.com/showthread.php?t=1259613
http://forums.macrumors.com/showthread.php?t=1269712

I'm not sure if it's just AT&T or the 4S itself (haven't read the above threads).

 

Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3)

AT&T its always been like that but it's probably due to apple using a better speaker so it brings out the noise more

 

Hmm...I've been with AT&T for 10 years and the 4S is the only phone I've ever used that has had this "crackle" in the ear piece. So, no...I don't think it's AT&T.

OP, there are lots of us that have experienced this. On mine, it's random and doesn't happen on every call. I'm hoping it's environmental or software related (although that may be reaching) and that it can be fixed with a software update. But I've gotten used to it and everything else about my 4S is perfect, so I won't be exchanging it for this issue.

 

I think it might be an iOS 5 thing even, as I had it happen to me several times on my 3GS. Just overall static and white noise in the background. But then again, it could also be bad network connection with AT&T. Let's just hope they fix this with 5.0.1!

 

I have the same problem and I'm on verizon network. It might be the phone or ios5.