Voice over Internet Protocol is a general term for a family of transmission technologies
for delivery of voice communications over IP networks such as the Internet or other packet-switched networks.
Other terms frequently encountered and synonymous with VOIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband
Internet telephony refers to communications services — voice, facsimile,
and/or voice-messaging applications — that are transported via the
Internet, rather than the public switched telephone network (PSTN). The basic steps involved
in originating an Internet telephone call are conversion of the analog
voice signal to digital format and compression/translation of the signal
into Internet protocol (IP) packets for transmission over
the Internet; the process is reversed at the receiving end.
VOIP systems employ session control protocols to control the
set-up and tear-down of calls as well as audio codecs which encode speech allowing
transmission over an IP network asdigital audio via an audio stream. Codec
use is varied between different implementations of VOIP (and often a range
of codecs are used); some implementations rely on narrowband andcompressed speech,
while others support high fidelity stereo codecs..