In addition to the echo, background noise is really bad during VoIP calls. This comment has some interesting details: https://code.google.com/p/android/issues/

In addition to the echo, background noise is really bad during VoIP calls. This comment has some interesting details: https://code.google.com/p/android/issues/detail?id=41626#c20 https://code.google.com/p/android/issues/detail?id=41626#c20