We previously reported on an issue where the iPhone generates echoing and background noise on the receiving end of phone calls. Most users reporting this problem describe a situation where "everyone can hear themselves in the background." We noted that the receiving end echo can sometimes be resolved by using the included headset mic, but may result in a situation where the iPhone user instead hears an echo, and also that this issue has been extant with other phones as well, generally attributed to an issue with the carrier (AT&T in this case) rather than the device. In these cases, the problem is simply a bad connection, resolved by hanging up and initiating a new phone call. However, the echoing appears consistent for some iPhone users regardless of connection quality.
Finally, we noted that turning down the iPhone volume, avoiding cupping the bottom of the iPhone with your palm when not using the headset and using Bluetooth headsets have all proven effective in reducing the issue's severity. These workarounds are effective because one potential cause (in some cases) of the problem seems to be design-inherent; that is, audio from the iPhone's earpiece travels to the receiver, generating the echo.
Users continue to report the issue with frequency (we're experiencing it on a regular basis in-house). iPhone Atlas reader Adrian Bellomo writes:
"I'm definitely experiencing the 'echo' on the receiving end of the calls that I place. It's very annoying for the people I call."
It now appears that Apple is replacing units for some users reporting the problem, and some of those receiving replacements report that the problem does not exist on the new units.
A poster to Apple's Discussion boards, SeeBee, wrote: "All in all I think there is a big difference in the echo issue from the new iPhone and the old one."