At work, unless something requires immediate attention, communication is through email or IM. Calls are scheduled ahead of time and I have never checked voice mail on my office phone. My cell phone voice minutes for work peaked around mid 2007 and have gone down every year since.
The problem with the telephone is that every communication assumes highest priority. When the phone rings there is no way to tell if it’s communication that really does need to happen right now or something that could be handled later. You have to stop whatever you’re doing and answer the phone despite knowing that there is a high probability that whatever it is will be less important that what you’re doing at the moment. Fortunately, email and instant messaging have allowed us to stop using the phone for non-priority communication.