Margo Reyna
Regulatory Analyst
Enron Corp., Government Affairs
Phone:  713-853-9191

----- Forwarded by Margo Reyna/NA/Enron on 01/19/2001 03:32 PM -----

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		 Subject: Telecom Services: Competitive Local Exchange Carriers: Glossary of 
Communications Terms


Glossary of Communications Terms 
  
01/15/2001 
PC Magazine from ZDWire 
Copyright (c) 2001 ZD Inc. All Rights Reserved. 
Attenuation The decrease in a signal's power from transmission to reception. 
The received signal is lower in power because of such factors as line 
resistance, distance and network configuration.
Backbone The part of the network used as the main path for carrying traffic 
between network endpoints. 
CLEC (competitive local exchange carrier) An LEC that competes with the 
incumbent local exchange carrier (ILEC) in a given market. A company may be 
the ILEC in one market and CLEC in another.
CO (central office) A telephone company facility serving a specific area. One 
or more phone lines run from a subscriber's home or office to a CO.
Crosstalk Interference on analog lines created by cables that are too close 
together. Crosstalk may produce static, buzzing, or multiple conversations on 
one line.
Digital loop carrier Equipment used to concentrate many local-loop pairs onto 
a few high-speed digital pairs or one fiber-optic pair for transport back to 
the central office. DLC systems reduce wiring cost.
DOCSIS (Data Over Cable Service Interface Specification) A relatively new 
industry standard defining how cable modems communicate over cable TV lines. 
Any DOCSIS modem will work on any DOCSIS-compatible cable data network.
DSL (digital subscriber line) A technology that provides high-speed, two-way 
data communications over analog phone lines. DSL operates on a higher 
frequency and doesn't interfere with existing phone service. The most widely 
deployed variety is ADSL (asymmetric DSL), which provides downstream speeds 
of 144 Kbps to 2.2 Mbps and upstream channels from 90 to 640 Kbps, depending 
on the distance from the CO. See HDSL, IDSL, SDSL, and VDSL.
ELEC (enterprise local exchange carrier) A corporation operating as its own 
LEC to obtain better carrier rates. An ELEC may sell services to other 
carriers from a separate profit center.
Firewall Software or hardware that filters or blocks traffic from a public or 
private network, preventing unauthorized or unrecognized access.
G.Lite An ITU standard for DSL technology that delivers 1.5 Mbps downstream. 
Pronounced "gee-dot-lite."
HDSL (high-bit-rate digital subscriber line) A flavor of DSL that delivers up 
to 1.544 Mbps of data symmetrically over two copper twisted-pair lines. The 
range of HDSL is limited to 12,000 feet; signal repeaters extend the service 
farther from the CO.
Head end The cable company's main signal reception and distribution facility. 
The head end is the cable TV equivalent of a phone company CO, and all TV 
cables for a given area route back to a single head end.
IDSL (ISDN digital subscriber line) A form of DSL providing a symmetrical 
speed of 144 Kbps over the copper wire provisioned for ISDN. Repeaters enable 
service up to 35,000 feet from the CO.
ILEC (incumbent local exchange carrier) A LEC dominating the local market.
IP address A numerical identifier for a device on a TCP/IP network. The IP 
address format is a string of four numbers, each from 0 to 255, separated by 
periods.
ISDN (Integrated Services Digital Network) An all-digital replacement for 
analog telephone service. ISDN provides two 64-Kbps channels, called 
B-channels, over a single phone line, which can be used together or 
independently to carry voice or data. The data signaling channel, or 
D-channel, carries signaling and limited packet communications at either 16 
or 64 Kbps, depending on the service.
LEC (local exchange carrier A local telephone company.
POTS (plain old telephone service) Standard telephony for placing and 
receiving calls.
PPPOE (Point-to-Point Protocol over Ethernet) A protocol that allows DSL 
providers to meter connection time and to acquire a smaller, cheaper block of 
IP addresses. PPPOE changes DSL from an always-on to an on-demand service and 
lets providers reduce the size and cost of their Internet connection 
infrastructures.
RBOCs (Regional Bell Operating Companies) The seven companies that were 
created after AT&T's divestiture in the mid-eighties. Also known as Baby 
Bells.
SDSL (symmetric digital subscriber line) A form of DSL that transfers data 
upstream and downstream at symmetric rates of up to 2.3 Mbps over a single 
copper twisted-pair line.
T1 A digital carrier technology used for transmitting data through the 
telephone system at 1.544 Mbps.
T3 A digital carrier facility used for transmitting data through the 
telephone system at 45 Mbps.
VDSL (very high data rate digital subscriber line) An evolving form of DSL 
that can deliver data at a rate of 13 to 52 Mbps downstream and 1.5 to 2.3 
Mbps upstream over a single copper twisted-pair line. The operating range of 
VDSL is up to 4,500 feet from the CO.
VOIP (Voice over IP) Software and hardware that allow voice signals to be 
carried over an IP-based network with POTs quality and reliability. VoIP 
segments the signal into frames, which are stored as voice packets.
VPN (virtual private network) An authentication, encryption, and 
data-packaging technology that lets private network traffic travel over the 
public networks. VPNs provide remote offices and telecommuters with secure 
access to a corporate LAN or WAN. Because VPN traffic is encrypted, it cannot 
be deciphered as it travels over the Internet.
WLL (wireless local loop) A broadband connection system that uses 
high-frequency radio links to deliver voice and data without the problems of 
gaining right-of-way for a fiber-optic cable installation or finding adequate 
copper connections for DSL. Also known as fixed-point wireless. 

Folder Name: Telecom Services: Competitive Local Exchange Carriers 
Relevance Score on Scale of 100: 66

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