I have an issue using Voix phone where people who I am talking to using Voix can hear an echo of themselves. I cannot hear it on the Voix end, but the other end can and I have confirmed this. I have tried turning echo cancelation on and off in voix phone and it does make a difference. I do not have this problem using other softphones.

I am using Voix phone using the IAX protocol with asterisk 1.4 and speex codec.

on which platform do you have this problem?

Windows. I have not tested Mac or linux.

Specifically Windows XP.

We had an issue on linux, with people speaking in the same room the problem was caused by the headset (usb) and we solved lowering the microphone level