Telephony is closely linked to the evolution of technology for the development, application, and distribution of telecommunication services. The development of the electronic transmission of voice, fax, or data has progressed to a point where telephonic equipment is employed in the transmission of speech or other sound between distant points without the use of wires.
Telephony is commonly associated with computer hardware, software, and computer network systems and specifically, Internet telephony, or voice over Internet Protocol (VoIP).
VoIP phones are hardware- or software-based telephones used in VoIP technology to convert outgoing analogue audio into a digital format that can be transmitted over the Internet. VoIP phones also convert incoming digital phone signals from the Internet to standard telephone audio signals.
VoIP phones, also referred to as IP phones, have more features than those found in traditional analogue phones. They are packed with additional performance qualities since signals are transmitted over the Internet and not the legacy public switched telephone network (PSTN).
How does a VoIP phone work?
VoIP phones either use A/C adapters or Power over Ethernet (PoE) power with an Ethernet cable which eliminates the need for separate power and data cables. Networking components are required such as an assigned IP address through 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.
The most commonly used VoIP protocols required support audio, video and data communications across IP networks. These protocols enable several VoIP functions, including bandwidth management and call control. Session initiation protocol (SIP) is a signalling protocol that sets up VoIP connections and a Real-Time Transport Protocol (RTP) is used to send and receive multimedia data between two devices.