What Causes Echoing on an iPhone?by Marie Cartwright
An echoing iPhone can make it almost impossible to conduct a conversation. Though echoing has not been reported as frequently in the iPhone 3GS or the iPhone 4, this irritating issue isn't uncommon in the iPhone 3G and the first-generation iPhone. Echoing can be caused by a number of factors -- including cellular network problems -- several of which you can fix.
If the echo on your iPhone is not a constant problem, it's likely that your trouble is due to issues with your cellular network, rather than the device itself. Being in a place with poor service can cause many call quality issues, including echoing. Make a call from a location with better service. You can even just hang up and call right back without changing your location. Sometimes simply establishing a new connection will get rid of that echo.
Since the microphone and the speaker on your iPhone are not very far away from each other, if your speaker is turned up too high, your microphone can pick up the sound. This can cause an annoying echo loop. Simply turn down the speaker volume. If you're having trouble hearing the person on the other end, use the iPhone's headset. Piping the sound directly into your ears will prevent the microphone from transmitting any unwanted sound.
Cupping the Microphone
Believe it or not, the way that you hold your iPhone can be a big factor in whether or not you're experiencing an echo. Cupping the bottom of the iPhone with your hand can inadvertently create a mini echo-chamber. When holding your iPhone during a call, keep your palm and fingers well away from the microphone. Hold the edges of the frame only. This very basic solution can prove to be effective.
Using an iPhone in conjunction with a Bluetooth audio system in a car has resulted in echo problems for some users. According to a 2008 review by tech site CNET, this issue affects only iPhone 3G users. Not all cars are affected, either. The mysterious Bluetooth echo problem is limited to various models of BMWs, Infinitis, Nissans, and Toyotas, as well as the Ford Focus. Turning off the 3G network on your phone when making a call through your car's audio system can solve this problem.