For consultants working out of our homes, how do we install IP phones that can share features over the internet? This may require Virtual Private Network, but VPN can get expensive.

Our vendor suggested we switch the small business phones to IP phones. We are expanding from 12 employees to 18. What are IP phones?

I need a pbx style phone system in my business but I dont have the funds for a traditional system. I have a wired/wireless ethernet system already installed throughout my business and was wondering if there was a way to use IP phones through the network internally without an outside VOIP service provider?

If I wanted to use an IP Phone do I need a VoIP service provider? And what do I need to get started (hardware)?