I have done various searches here and elsewhere regarding call quality of the 4S (both to you and the person whom you are calling) and really have not got a good handle as to whether there is a material improvement in the voice quality of the calls *when* signal strength is good - let's say 4 bars minimum or say -90 dBm. I am thinking of buying a 4S (while keeping my 4 as a backup) but it is not because of the cpu, or siri. My main reasons for upgrading would be the antenna issue (I don't like using cases with my 4 anymore but simply work around the problem) which I know is essentially fixed with the 4S and also if there is a real voice quality improvement in calls (not interested in the quality of the speakerphone or using Bluetooth). Before someone says "just try it out", here with Rogers (and others in Canada) any return must be within 14/15 days or 30 minutes call time, whichever comes first. As I said, it does not bother me if voice quality is less compromised with the 4S in areas of mediocre or poor signal quality. Simply how calls sound to you and how you sound to the other party when the signal is strong. I am probably more interested in how I sound to others as I use this phone a lot for business calls when I am in my study.