136 APPENDIX : GLOSSARY
OOBMAN Out-of-band Manager—OOBMan is an application that runs on 3Com
Windows NT components of the CommWorks IP Telephony platform.It is designed to allow a user to dial into an NT device, using a terminal emulation program such as Hyperterminal, and view or modify various configuration information on that machine.
OS Operating System—A software program that controls and manages the
operations of a computer system.
OOF Out-of-frame—OOF conditions occurs in a T1 transmission when two or more out
of four consecutive framing bits are in error.
OOS Out-of-service—The term used when a module or card is not functioning. It could
be because VoIP has taken it OOS due to errors, or because the card or module
has been removed from the chassis.
PCI Peripheral Component Interconnect—Designed by Intel. It is a 32-bit local bus on
a PC to transfer data between the CPU and the peripherals.
PCM Pulse Code Modulation—Technique for converting an analog signal to a digital
signal.
POTS Plain Old Telephone System—Standard telephone service used by most residential
locations. See PSTN.
PRI Primary Rate Interface—ISDN interface to primary rate access. In the U.S., the
Primary Rate Interface is split into 23 B channels and one 64 Kbps D channel. PRI is
delivered over the same physical link as a T1, or 1.55 Mbps link. In Europe, PRI is
split into 30 B channels and one 64 k bit/second D channel and is delivered over
the same physical link as an E1.
PSI Power Supply Interface—The card on the chassis that controls the power for the
chassis.
PSTN Public Switched Telephone Network—The analog dial-tone-type telephone
networks and services in place worldwide, with transmission rates up to 52Kbps.
In contrast, telephone services based on digital communications lines, such as
ISDN, have higher speeds and bandwidths. The POTS networks also called the
public switched telephone network (PSTN).
PSU Power Supply Unit—This unit is part of the Total Control chassis. It controls the
power to the chassis. The PSU can be either AC or DC power with 35A, 45A, 70A,
or 130A ratings.
QOS Quality of Service—An indicator of the performance of a transmission system on
the Internet and other networks. QoS is measured in transmission rate, error rates,
latency, and other characteristics, and can to some extent be guaranteed to a
customer in advance.
RAS Remote Access Service—Remote access is sending and receiving data to and from
a computer or controlling computer with terminals or PCs connected through
phone/communications links. A remoter access service provides this function.