Glossary
GL-2
Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (H.323)
OL-4008-01
compression The running of a data set through an algorithm that reduces the space required to store or the ba ndwidth
required to transmit the data set. Compare with companding and expansion.
CoS Class of service. An indication of how an upper-layer protocol requires a l ower-layer protocol to treat
its messages. In SNA subarea routing, CoS definitions are used by subarea nodes to determine the
optimal route to establish a given session. A CoS definition comprises a vir tual route number and a
transmission priority field.
D
DHCP Dynamic Host Configuration Protocol. Provides a mechanism for allocating IP addresses dynamically
so that addresses can be reused when hosts no longer need them.
dial peer An addressable call endpoint. In Voice over IP (VoIP), there are two types of dial peers: POTS and
VoI P.
DNS Domain Name System. System used on the Internet for translating names of network nodes into
addresses.
DSP digital signal processor. A DSP segments the voice signal into frames and stores them in voice packets.
DTMF dual tone multifrequency. Tones generated when a button is pressed on a telephone, primarily used in
the U.S. and Canada.
E
E.164 The international public telecommunications numbering plan. A standard set by the ITU-T which
addresses telephone numbers.
endpoint A SIP terminal or gateway. An endpoint can call and be called. It generates and/or terminates the
information stream.
expansion The process of running a compressed data set through an algorithm that restores the data set to its
original size. Compare with companding and compress ion.
F
firewall Router or access server, or several routers or access servers, designated as a buffer between any
connected public networks and a private network. A firewall router uses access lists a nd other methods
to ensure the security of the private network.
FoIP Fax over IP
FQDN Fully Qualified Domain (FQDN) format “mydomain.com” or “company.mydomain.com.”
FSK Frequency shift key.