I don't know if this is just a limitation of voip phone systems, or my specific configuration, or what... If I'm talking to someone from an Aastra or Cisco handset or the 3CX Windows Soft Phone, and the person I'm talking to tries to say something, I often cannot hear what they are saying (instead, I hear a sort of white noise). Sometimes they are agreeing with something I've said, sometimes they are trying to interrupt me, but it almost always derails the conversation for a second or two. This also happens if I call someone and get put on hold. When listening to the music on hold, if I speak, the music sort of turns to a white noise. I'm using a Grandstream FXO gateway with the latest firmware. I'm not sure if there is something I can do to tune this or not, either in 3CX or the gateway or elsewhere.