Nortel VoIP Gateway, Configuration Manual

Page: 213 / 220

Glossary 213
Norstar VoIP Gateway Configuration Guide
modem
Device that converts serial data from a transmitting terminal to an analog device for
transmission over a telephone channel. Another modem converts the signal to serial digital
Noise.
network diagram
This is a physical drawing/description of how the local network works to which your VoIP
Gateway will be connected. It also includes information about the VoIP Gateway
requirements, such as public and/or private IP addressing, DHCP requirements, and
quality of service availability. Where possible, it should include information about the
public networks and any changes or adjustments required by the network or the VoIP
Gateway for compatibility.
packet
Group of bits transmitted as a complete package on a packet switched network.
public switched telephone network (PSTN)
A telecommunications network based on circuit switching technology. A link is busy for
the duration of the connection.
Ping
This utility is used to echo messages to a host over an IP network. This allows you to find
out if the other point is available. Ping also can include statistics about how long it took
from end to end, which provides information about routing.
prioritization
This refers to how a voice data packet is set up in the VoIP Gateway so that external
routers recognize it as having a high priority, thus shortening delay times and increasing
the perception of voice quality over VoIP trunks.
QoS (quality of service) routing
To minimize voice jitter over low bandwidth connections, the VoIP Gateway programming
assigns specific DiffServ Marking in the IPv4 header of the data packets sent over VoIP
trunks. During the packet journey through the network, including any routers on that
network, the header specifies a level of priority service. This is quality of service routing.
For QoS to be successful for IP telephony, it must be end-to-end on the network.
silence compression/silence suppression
This is the utility that omits the data packets that occur when no one is talking during the
IP trunk calls, thus reducing the bandwidth load required for IP calls.
target lines
These are internal channels on the Norstar KSU that allow you to direct incoming calls to
specific telephones, call groups/Hunt groups, or system devices.