Since you are hearing echo, the problem is in the computer of your roommate. Your voice is sent to your roommate but the computer and then it bounces back at you as echo.
I suggest the following tests:
1. Check again all the echo cancellation settings in your roommate computer.
2. Ask your roommate to lower the volume the speakers. This should improve echo cancellation handling.
3. If possible ask your roommate to use headsets. It should completely get rid of the echo.
4. If all the above do not help, ask your roommate to try an echo canceling software
like SoliCall Pro.