- Asymmetic Digital Subscriber Line. A digital line that uses
the existing twisted pair copper telephone network to achieve
speeds of up to 6 megabits per second up to 12000 feet, or 1.5
megabits per second up to 18000 feet.
- Providing differing bandwidth in different directions. 56 K
modems are asymmetrical: they offer a maximum speed of 56K for
downloading, but only 28.8K or 33.6K for uploading.
- A measure of signal changes per second. Often used
incorrectly in place of bps (bits per second).
- bits per second.
- Basic Rate Interface. A consumer grade ISDN line consisting
of 2 64K bearer channels and one 16K delta (controller)
- Competitive Local Exchange Carrier. An alternative to the
existing local phone company.
- International Consultative Committee on Telecommunications
and Telegraphy. The CCITT acronym comes from the French
Commite' Consultatif International de Telegraphique et
Telephonique. An international standards body. Known as the
ITU-T since March 1, 1993.
- Central Office, in reference to the phone company's central
switching station for a given area.
- Converting analog signals back into digital signals. A
modem is a MOdulator/DEModulator.
- A high-speed line capable of delivering 1.54 Mbps (1,540K)
in both directions, and divided into 24 data-bearing
- A high-speed line capable of delivering 3.15 Mbps (3,150K)
in both directions.
- A high-speed line capable of delivering 6.31 Mbps (6,310K)
in both directions.
- A high-speed line capable of delivering 44.7 Mbps (44,700K)
in both directions.
- Digital signal processor. A specialized processor, usually
for handling audio or video signals.
- Digital Simultaneous Voice and Data.
- Roughly the European equivelant of a T1 or a PRI, but with
30 data-bearing channels
- First In, First Out. A type of data buffering that prevents
data loss during high-speed communications.
- Host signal processor. In modems, a modem that depends on
the host CPU (the Pentium, PowerPC, etc., in the main computer)
for part or most of the data processing.
- A device that converts the two-wire local loop to the
four-wire central office.
- Integrated Services Digital Network. A digital phone
service capable of speeds from 57.6 K to 128 K. Provides two
data channels, each with its own phone number, making
simultaneous voice and data possible.
- Internet Service Provider. A company that provides access
to the Internet through modems, ISDN, T1s, etc.
- International Telecommunications Union. An international
standards body. Known as the CCITT prior to March 1, 1993.
- Lucent and Rockwell's joint 56K modulation protocol that
makes Rockwell's K56Plus and Lucent's V.flex2 technologies
- Rockwell's proprietary protocol for 56000 bps modulation.
Merged with Lucent's V.flex to create K56flex.
- kilobits per second. KBps is kilobytes per
- local loop
- The copper wires running between the telephone subscriber's
home or business and the phone company switch.
- megabits per second. MBps would be megabytes per
- A MOdulator/DEModulator. A device that can encode digital
signals from a computer into analog signals that can be
transmitted over analog lines, and vice versa.
- Converting digital signals into analog signals. A modem is
- A fiber optic line capable of 155 megabits per second
- A fiber optic line capable of 2400 megabits per second
- Pulse Code Modulation. A method of encoding an audio signal
in digital format.
- Personal Computer Memory Card International Association. A
standard for miniturized laptop expansion cards for modems,
storage, and other devices. Often called PC cards.
- Point of Presence. A local dialin point for an Internet
- Plain Old Telephone Service. Regular analog phone service,
as opposed to ISDN, ADSL, and other digital phone
- Primary Rate Interface. An industrial grade ISDN line. In
the United States and Japan, a PRI consists of 23 64K bearer
channels and a 64K delta (controller) channel. In Europe, a PRI
consits of 30 bearer channels and a delta channel.
- Public Switched Telephone Network.
- Regional Bell Operating Company.
- Rockwell Protocol Interface. A type of HSP modem that is
limited to 14.4 connections.
- providing equal speeds in both directions. Compare with
- In North America, a digital carrier for a DS1-formatted
- In North America, a digital carrier for a DS3-formatted
- Universal Asynchronous Receiver-Transmitter. A controller
chip that processes data coming in and going out of the modem.
The 16550 is a modern example.
- AT&T's proprietary protocol for 19200 bps asynchronous
- The ITU standard for 14400 bps modulation.
- The ITU standard for 28800 bps modulation.
- The ITU standard for 56K modulation.
- Rockwell's proprietary protocol for 28800 bps asynchronous
- Lucent's proprietary protocol for 56000 bps modulation.
Merged with Rockwell's K56Plus to create K56flex.
- U.S. Robotics' proprietary protocol for 56K
Glossary of Telecommunications Terms