VOIP is here to stay, business are rolling out with it through there companies as its more cost effective. I think VOIP will have a larger market share then regular phone systems in the next few years in the business sector.
I would agree with you there - I can see its attractions. The place where I am studying a-levels has it. Also it makes a cheap way of chatting to your mates over the net (using the likes of skype)
First of all I am not an expert, so don't rely on my advice but I think getting in the well established business's is good idea. I strongly advise doing some research into the VoIP markets, also I suspect you will find at least some of the VoIP company's don't just spe############e in VoIP.