Specifications

Appendix C - Glossary Administration Manual (SIP/MGCP Version)
AT-VP504E FXS 134
Off-hook A line condition caused when a telephone handset is removed from its
cradle.
On-hook A line condition caused when a telephone handset is resting in its
cradle.
Packet Includes three principal elements: control information (such as
destination, origin, length of packet), data to be transmitted, and error
detection and A group of bits, including data and control signals,
arranged in a specific format and transmitted as a whole. The structure
of a packet depends on the protocol.
Plain Old Telephone
System (POTS)
Standard telephone service used by most residential locations; basic
service supplying standard single line telephones, telephone lines, and
access to the public switched network.
Port Network access point, the identifier used to distinguish among multiple
simultaneous connections to a host.
Portable Operating
System Interface
(POSIX)
POSIX is a set of standard operating system interfaces based on the
UNIX operating system. The need for standardization arose because
enterprises using computers wanted to be able to develop programs
that could be moved among different manufacturer's computer
systems without having to be recoded. UNIX was selected as the basis
for a standard system interface partly because it was "manufacturer-
neutral." However, several major versions of UNIX existed so there
was a need to develop a common denominator system.
Private Branch
Exchange (PBX)
A small to medium sized telephone system and switch that provides
communications between onsite telephones and exterior
communications networks.
Programmable Read-
Only Memory (PROM)
A memory chip where data is written only once as it remains there
forever. Unlike RAM, PROMs retain their contents when the computer
is turned off.
Protocol A formal set of rules developed by international standards bodies, LAN
equipment vendors, or groups governing the format, control, and
timing of network communications. A set of conventions dealing with
transmissions between two systems. Typically defines how to
implement a group of services in one or two layers of the OSI reference
model. Protocols can describe low-level details of machine-to-machine
interfaces or high-level exchanges between allocation programs.