Voice over IP (or VoIP for short) is basically operating a telephone-type service across an internet-like network. The network can be the Internet itself or any Local Area Network (LAN).

VoIP services are extremely scale-able and can usually be integrated with any existing PSTN services. There are also VoIP Service Providers (VSPs) that perform some of the more expensive or more intricate interconnections, charging a much more palatable monthly fee to the user. There are commercial and free (usually Open Source) exchange-like software, typically configured as a Private Automated Branch Exchange (PABX) - similar to what a lot of larger organisations use, in addition to being a more intelligent and configurable option that a Commander-like system.

Four broad typical configurations are:

• Mini - typically useful for a Home or Home/Office,
• Small - typically useful for a Small Businesses,
• Medium - typically useful for Most Businesses, and
• Large - for those whose needs exceed the others.

Each is described in more detail on the linked pages.