VoIP in a Nutshell
Everything you need to know
about
Voice-over-IP in one convenient location.
VoIP "Voice-over-IP" As defined by the
TechEncyclopedia: The two-way transmission of audio over a
packet-switched IP network (TCP/IP network). When used in a private intranet or WAN, it is
generally known as 'voice over IP,' or 'VoIP.' When the transport is the public Internet
or the Internet backbone from a major carrier, it is generally called 'IP telephony' or
'Internet telephony.'
These are some of the terms you're going to come across in reading about (and working
with) VoIP, and a rough idea of what they mean.
Note: This list is deliberately not in alphabetical order, so as to facilitate
understanding and clarity.
INTERNET PROTOCOL
The "IP" in voice over IP. It's one of a large family of specifications that
define the transmission of information over data networks. But this one is particularly
critical because it tracks the Internet addresses of nodes, routes outgoing messages, and
recognizes incoming messages. It's the backbone -- or more figuratively, the language --
of the Internet.
VOICE OVER IP
The technology used to transmit voice conversations over a data network using the
Internet Protocol described above. The data network involved might be the Internet itself,
or a corporate intranet, or managed networks used by local or long distance carriers and
ISPs. Who runs the network doesn't matter -- what does is the fact that you're taking
voice (i.e., analog information) and encoding it digitally, converting it into packets,
and then using a data network to move those packets along the most efficient path to their
destination, where they get reassembled and delivered in the format they started in:
voice.
IP TELEPHONY
A term used largely interchangeably with Voice over IP and VoIP to describe the
transmission of voice -- in this case referring more specifically to voice in the form of
live calls, rather than messages -- over data networks.
LATENCY
The average "travel" time it takes for a packet to pass through a network.
The lower the latency, the better the voice quality.
PSTN
The public switched telephone network that traditionally routes voice calls from one
location to another. The UN-VOIP.
DYNAMIC JITTER BUFFER
The dynamic jitter buffer collects voice packets, stores them, and shifts them to the
voice processor in evenly spaced intervals to reduce any distortion in the sound.
DiffServ
Differentiated Services - a quality of service protocol that prioritizes IP voice and
data traffic to help preserve voice quality even when network traffic is heavy.
FXO
Foreign Exchange Office - the interface on a VOIP device for connecting to an analog
PBX extension.
FXS
Foreign Exchange Station - the interface on a VOIP device for connecting directly to
phones, faxes, and CO ports on PBXs or key telephone systems.
Other terms you might see: Voice over Frame Relay (VoFR), Voice over DSL (VoDSL), Fax
over IP (FoIP). All should be fairly self-explanatory by now. See VoIP Glossary
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