Voice Over IP

IP Telephony also called Internet telephony, is the technology that makes it possible to have a telephone conversation where the signal is carried over the Internet or a dedicated network in Internet Protocol (I P) packets, instead of over dedicated voice transmission lines. This allows the elimination of circuit switching and the associated waste of bandwidth. Instead, packet switching is used, where IP packets with voice data are sent over the network only when data needs to be sent, i.e. when a caller is talking.

Its advantages over traditional telephony include:

lower costs per call, especially for long-distance calls
lower infrastructure costs: once I P infrastructure is installed, no or little additional telephony infrastructure is needed.
new advanced features.
Note that voice over IP traffic does not necessarily have to travel over the public Internet: it may also be deployed on private IP networks.

The protocols used to carry the signal over the I P network are commonly referred to as Voice over I P, or VoIP protocols.