There's a tendency in the VoIP business to think that every SMB (small- to medium-sized business) wants its phone system to have fancy IP PBX features; abilities like transferring a call by dragging and dropping an icon in an on-screen interface, or using that same interface to see whose line is busy. But a lot of small companies like their old-fashioned key phone systems just fine. When a call arrives on those phones, the button for line 1 lights up on everyone's set, and someone pushes their button 1 to answer. That person then shouts across the room, "George, it's Joe on line 1." George pushes his button 1 and starts talking to Joe. In a small office, shouting is quicker and easier than pressing several keys or finding the right on-screen window to transfer a call. Too bad IP PBXes don't allow it.