I have a Mitel 5000 ver 3.2.4.62. It has the older Inter-tel phones. After checking for compatiblity, we bought some new Mitel 8528 phones. They work, except for one MAJOR issue. If you are on speakerphone and press any key, the beep is super loud! I mean hurt your ears loud. I tried adjusting the volume but that did not work. Is there is a way I can reduce or shut off the tone on a keypress? Thanks.