VOip has been the talk of telco for 3-4 years now. There are a number of problems with it which are still being worked on. For businesses in particular, they require special VOip phones which are very expensive.
VOip is the claim of the future, but most telco's have yet to get a stable platform. I could tell you a number of VOip nightmares experienced with businesses back when I was with SBC, and TDS.
One of any number of problems is if you lose power, you are effectively out of business. Unlike a landline, unless you have a phone system w/ backup. A landline has a signal provided power by a generator back at the central office. So as long as you do not have a phone that needs power to operate, you still atleast have phones, and voicemail or answering service if hosted at the central office, and not within the phone system.
I think Vonage, and residental is ahead of the business applications at this point in time. I'd say VOip is prolly another 1-2 years away from being a seriously viable alternative.
