When I used Google voice to make a call, the other side informed me that he could hear his echo. The reason is that I was using my laptop's internal microphone as input and internal audio stereo as output for me, which could send back any sound played out by the internal stereo. So I wonder how to prevent the other side can hear his echo? Thanks!
I had the same problem. I fixed it by turning on echo cancellation on the device. I am using Windows 7. It is under the properties setting on the microphone. I have made two phone calls now and the echo on the other end is gone. They no longer here their voice echo. I hope this helps.