Hi, we are having the same exact problem. All the menu sounds play fine, no screeching till the user presses 9, you can record over the screeches and they don't come through. Muting the mic on the caller's phone doesn't help so its not actual feedback from their end. Could be a PC setting? Would love to know if you figured it out yet! If we get it we'll post here. I emailed support as well but you know how that goes.