VOIP is an acronym for Voice Over Internet Protocol, or in more common terms phone service over the Internet.
If you have a reasonable quality Internet connection you can get phone service delivered through your Internet connection instead of from your local phone company. Initiatel.com - What is Voip?
Most of us have high speed Internet in our homes -- so why not use the Internet to connect your whole house directly to a new (and cheaper) phone company's network? Quite simply, that is what VoIP can do for you.And yes, you can connect your whole house to VoIP [§8], and you can continue to use all of the phones that you are using right now. Nothing changes. You just plug your new VoIP device into a spare port on the router connected to your Internet modem. Learn More
A business VOIP phone system can reduce your monthly phone bill tremendously compared to a traditional business phone system. A business VOIP solution can be a hosted PBX system, as well as an on-premise PBX solution. Initiatel.com - What is Business Voip?
Simplicity at its finest…! A service offering functionality of a PBX without the need to install switching equipment at the customer location. Only VOIP phones need to be installed at the customer site. This makes supporting distributed workers very easy as each requires only and internet connection and a VOIP phone. A business virtual PBX phone system can reduce your monthly phone bill significantly compared to a traditional business phone system.Learn More