Working on a new install with all new parts DK424 with BB4 processors (problem appears on my test 424i system also)The problem appears in tone first mode only. Here is the problem. When an extension is busy and that busy extension is dialed from another extension the phone will emit a muted ring like a busy override instead of being busy. Switch to voice first by pressing the digit 1 when the called party remains busy then the caller gets the busy signal. Thats what I want is the busy signal. I dont want the busy override. I dont want forwarded. Just a good ol fashioned busy to be heard by the caller. Ive tried prog*34, 35,30,31, 10-1,10-2 and every other prog that seemed to pertain. prog 5 may be next. I even tried smashing my 2020SD beater phone into tiny bits upon the concrete floor. Nothing seems to work I've been working nearly nonstop at the trouble for 4 hours with only the press one for voice -first workaround as a temp solution. Any suggestions will be welcomed THANKS