I don't think businesses are ready to give up their landlines just yet. Confrence calls are still too big a part of what a lot of us do, and it's hard to screen calls in to your manager when someone has a direct line to them.
Residents, however, are a different story. Out in the Seattle area, I know from talking to some other vendors that it's almost impossible to get a new resident to sign up for phone service unless you bundle it with something else. They just don't want it at all. I guess Lisa Trosien is right... the real amenity is 5 bars of signal
We're about to embark on a new phone system for our properties that runs through a VOIP hub. Basically, the phones will operate like they have in the past, but we'll have so many more options for tracking calls, etc. We'll also be able to reduce our phone bills substantially.
Be watchful of tricky contracts that are out there for VOIP systems. Make sure you read the fine print well. Other than that the technology has greatly improved and does save alot of money.