Multi-Tech Systems Voice Over IP Technology Guide

							VOIP Terms
bad frame interpolation interpolates lost/corrupted
packets by using the previously received voice frames. It
increases voice quality by making the voice transmission
more robust in bursty error environments.
compression is used at anywhere from 1:1 to 12:1 ratios
in VOIP applications to consume less bandwidth and
leave more for data or other voice/fax communications.
The voice quality may decrease with increased
compression ratios.
DiffServ (Differentiated Services) is a quality of service
protocol that prioritizes IP voice and data traffic to help
preserve voice quality even when network traffic is heavy.
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.
E&M (Ear and Mouth) is the interface on a VOIP device
that allows it to be connected to analog PBX trunk ports
(tie lines).
forward error correction increases voice quality by
recovering lost or corrupted packets.
FXO (foreign exchange office) is the interface on a VOIP
device for connecting to an analog PBX extension.
FXS (foreign exchange station) is the interface on a VOIP
device for connecting directly to phones, faxes, and CO
ports on PBXs or key telephone systems.
H.323 is an industry-standard call setup protocol
designed to standardize VOIP communications between
other H.323 telephony solutions.
ITU G.723, G.726/G.729 and G.711 are some of the
standards developed for compression technologies.
latency is the average “travel” time it takes for a packet
to pass through a network. The lower the latency, the
better the voice quality.
PSTN is the public switched telephone network that
traditionally routes voice calls from one location to
another.
SIP (Session Initiation Protocol) is a signaling protocol
for Internet conferencing, telephony, multimedia and other
types of communications over the Internet.
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