VoIP is the acronym for Voice over Internet Protocol. It simply means that voice spoken into a handset is converted to a digital signal (vs. traditional analog signal around since Alexander Grahm Bell) and is transmitted over the Internet instead of the normal switched phone company system. But this turns out to be a very big deal because it allows VoIP to do far more than just deliver lower cost per minute on long distance. As a matter of fact, lower cost per minute is only a secondary feature of VoIP. VoIP eliminates many complicated and expensive add-on services normally billed by the traditional voice carrier. It also allows businesses to better manage their voice users by enabling their administrator to add, delete and change voice lines at will from a desktop control screen. It eliminates the need to have the phone company send a technician in a van to the business location every time they want to add or change a phone line, number or handset.
VoIP can even allow users to have a phone number that they can receive calls on anywhere with a VoIP phone instead of being tethered to a traditional phone that is always sitting stationary on a desktop back at their work office. Because it's over the Internet, using a VoIP phone service is very much like being able to use your Internet ISP to get email or browse the web anywhere you can get an Internet connection.
VoIP also allows the integration of voice services over the company data network and thereby potentially eliminates the need for operating two separate networks of one for voice (i.e. PBX or Key System and separate phone cabling) and one for data. However, there are many different ways that companies can integrate VoIP functions, and the wise agent partner or customer will take some time to do their homework on what type of VoIP deployment might be best for them. Browse here for more information on business VoIP solutions offered through AB&T Telecom.
Also see "Unified Communications" for more info