VoIP (Voice over IP), as the name implies, refers to the transmission of voice communications over IP networks. The term "VoIP" is widely used in both consumer and business markets.
For consumers, VoIP usually describes telephone service designed to replace traditional POTS (Plain Old Telephone Service). The major appeal of this new type of phone service is lower costs, both nationally and worldwide. The savings from routing traffic over the public internet is passed on to the subscribing consumers.
In business, Voice Over IP covers a much wider range of topics. One large focus is on the network equipment and infrastructure required to offer VoIP services to customers. You will also find frequent references to internal VoIP equipment in telecom environments. This equipment allows technicians and other employees communicate inexpensively over the company's existing bandwidth.
Sometimes, VoIP equipment is bundled with other network management devices in a single rack-mounted case. One example of this is the Voice Over IP RTU (Remote Telemetry Unit), which incorporates remote site monitoring with VoIP functionality.
When no one is present at a remote telecom site (which is most of the time), the RTU functionality provides a means of remotely monitoring and controlling equipment status from a central office. When a technician is on site for either planned or unplanned maintenance, the VoIP functionality (usually a simple handset plugged into the unit) allows that technician to communicate with other employees at other locations. This is especially useful when cell phone reception is poor in a very remote area.