A VoIP phone is a hardware- or software-based telephone designed to use voice over IP technology to send and receive phone calls over an IP network. The phone converts analog telephony audio into a digital format that can be transmitted over the internet and converts incoming digital phone signals from the internet to standard telephone audio.
VoIP phones, also known as IP phones, include features and capabilities not found in traditional analog phones. They also have additional performance requirements because phone calls are placed over the internet instead of the legacy public switched telephone network (PSTN).
Some VoIP phones require A/C adapters for power, while others use (PoE). PoE uses an Ethernet cable instead of an A/C adapter and removes the need for separate power and data cables.
Several networking components are required to make VoIP phones work. Phones are assigned IP addresses through the Dynamic Host Configuration Protocol (DHCP), which automatically configures the network and the VoIP parameters. A domain name system (DNS) tracks the IP addresses to enable devices, such as IP phones, to connect to each other.
VoIP phones require a number of protocols to facilitate the delivery of voice communications over the internet. H.323 is the most commonly used VoIP protocol that supports audio, video and data communications across IP networks. It provides several VoIP functions, including bandwidth management and call control.