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Voice & Data Terminologies

Learn how some of the basic terms associated with telecommunications and related technology solutions can help you to make more informed decisions.



Analog Transmission - Transmission of a continuously variable signal as opposed to a discrete on/off signal. Analog is the traditional way of transmitting a telephone or voice.

Asymmetric Digital Subscriber Line (ADSL) - Also referred to as Digital Subscriber Line (DSL), ADSL is a technology that enables data transmissions over existing copper wiring at data rates several hundred times faster than today's analog modems. ADSL was specifically developed for the simultaneous delivery of voice, video, and data to the home, which requires a higher downstream bandwidth than upstream bandwidth. Downstream ADSL data rates are as high as 8 Mbps, while upstream data rates can reach 1 Mbps. Fully symmetric data rates of up to 1 Mbps are also possible.

Centrex (Central Office Exchange Service) - Centrex is a service provided by local carriers. Business users are offered the carrier's phone facilities at the carrier's central (local) office.

(CSU/DSU) Channel Service Unit/Data Service Unit - An abbreviation for channel service unit and data service unit, which are components that provide for the connection of customer-premise computer equipment to a network.

DS1 (Commonly referred to as T1) - A data communications service for data-intensive businesses requiring high transmission speeds (1.544 Mbps). DS1 can transmit voice and data signals, or a combination of both usually over fiber. In the U.S., this is commonly referred to as T1.

DS3 (Commonly referred to as T3) - A data communications service for data-intensive businesses requiring extremely high transmission speeds (45 Mbps), usually over fiber. In the U.S., this is commonly referred to as T3.

Digital Signal - A discrete or discontinuous signal whose various states are discrete intervals apart, such as +15 volts and -15 volts.

Domain Name System (DNS) - The online distributed database system that is used to map human-readable addresses into Internet Protocol (IP) addresses.

Digital Subscriber Line (DSL) - See Asymmetric Digital Subscriber Line

Ethernet - A 100 Mbps technology based on the 10BASE-T Ethernet CSMA/CD network access method to accommodate the operation of local area networks (LAN's).

Fiber Optics - Communications technology that uses thin filaments of glass or other transparent materials. Fiber optic technology offers extremely high transmission speeds, and in the future, will allow for services such as "video on demand."

Frame Relay - A form of packet switching that allows high-speed, statistically multiplexed connectivity over a shared network. The technology depends upon high-quality transmission facilities, and makes the intelligent end-points responsible for the integrity of the data. Frame Relay is a connection based OSI level-two, switched service that transports packets through port speeds ranging from 56K to DS3. One of the distinct characteristics of the Frame Relay protocol is the ability to incorporate multiple connections, each with it's own specific class of service onto a port. This facilitates the simultaneous transmission of different applications over one connection.

Integrated Services Digital Network (ISDN) - switched network service providing end-to-end digital connectivity over standard phone lines for the transmission of voice and data. Two levels of service include Basic Rate Interface, a digital line with two 64 kbps voice/data channels and one 16 kbps signaling channel (2B+D), or Primary Rate Interface, a digital trunk with twenty three (23) 64 kbps voice/data channels and one (1) 64 kbps signaling channel (23 B+D).

Local Access Transport Area (LATA) - Also known as the Regional Calling Area, the area within which certain calling features can be used, such as Caller ID, Caller ID With Name, Intelligent 800 Service and Dedicated 800 Service.

Local Area Network (LAN) - An assembly of computing resources (such as PC's, printers, minicomputers and mainframes) linked by a common transmission medium, such as coaxial cable. Usually a LAN exists to serve a particular location, yet can be multi-location, or global in scope.

Multipoint - Verizon's Digital Data Service that utilizes an advanced nodal network architecture that allows numerous configurations including Multipoint, which connects three or more locations. This arrangement also reduces the request-to-send/clear-to-send delays experienced with analog.

National Television Systems Committee (NTSC) - Used in video telecom applications, NTSC is a standard established by the Federal Communications Commission (FCC) referring to 525 lines of resolution per second for color television broadcasts in the United States. The NTSC standard combines blue, red, and green signals with an FM frequency for audio. The FCC has ordered TV stations to replace this standard with HDTV transmissions beginning in the year 2003.

PBX - Private Branch eXchange - Telephone switch located at a customer's site that primarily establishes voice communications over tie lines or circuits as well as between individual users and the switched telephone network. Typically, also provides switching within a customer site and usually offers numerous other enhanced features, such as least-cost routing and call detail recording.

Point-to-Point - Verizon's Digital Data Service that utilizes an advanced nodal network architecture that allows numerous configurations including Point-to-Point, which allows the transmission of data between two locations, regardless of the exchange.

Point-to-Serving Wire Center - Verizon's Digital Data Service that utilizes an advanced nodal network architecture to permit numerous configurations including Point-to-Serving Wire Center, which represents a powerful arrangement for facilitating integration into other high capacity digital services.

Switched Ethernet Service (SES) - A high speed data service which uses a shared fiber network to allow for the interconnection of Local Area Networks (LANs) across selected metropolitan areas.

Note: Switched Ethernet Service (SES) was formerly known as Transparent LAN Service (TLS) and still appears in the tariffs as TLS.

SES delivers an interface from the Customer's LANs to the shared network at speeds of:

    10 Mbps
    100 Mbps
    1,000 Mbps (Gig-E)

SES creates a network with the ability to function as a shared public network. SES protects data privacy by using specialized screening software that permits subscribers to access only their data.

T1 (also referred to as DS1) - A data communications service that describes a facility that transports analog or digital format information at speeds up to 1.544 Mbps not over fiber.

T3 (also referred to as DS3) - A data communications service that describes a facility that transports analog or digital format information at speeds up to 45 Mbps not over fiber.

Wide Area Network (WAN) - Allows companies with multiple locations to link them together. A WAN encompasses a much larger geographic area than a LAN.

Wireless Services - A technology that permits communication without wire connections such as cellular phones and pagers.

About Your Educational Champion

Verizon "Verizon is an industry leader in wireline and wireless communications with one of the most reliable and advanced data networks in the world."

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Note: This information has been compiled by FERAD for educational purposes only in order to convey a general overview of the options and related services available to small businesses in the subject areas introduced. Content is provided on an "as is" basis and is not intended to be an exhaustive representation, nor does it provide advice or create a customer relationship between FERAD, buzgate.org, its affiliates and any other organization named herein, and any reader.
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