FAQs: Types of Data Circuits

Circuits that transport voice, video or data
Circuits that transport data only

Circuits that transport voice, video or data include:

T1

the most commonly used digital line in the United States, Canada, and Japan. In these countries, it uses time-division multiplexing (TDM) at an overall rate of 1.544 million bits per second (Mbps). T1 lines use copper wire and span distances within and between major metropolitan areas.

DS1

the digital signal with a transmission rate of 1.544 Mbps. Both the North American T-carrier system system (which includes the T1) and the European E-carrier systems of transmission operate using the DS series as a base multiple. The digital signal is what is carried inside the carrier system.

ISDN (Integrated Services Digital Network)

a set of standards for digital transmission over ordinary telephone copper wire as well as over other media. Home and business users can see highly-graphic Web pages arriving very quickly (up to 128 Kbps). ISDN is generally available from your phone company in most urban areas in the United States and Europe.

BRI

the Basic Rate Interface level of ISDN service, intended for the home and small enterprise. It includes a number of B-channels and a D-channel. Each carries data, voice, and other services. The D-channel carries control and signaling information.

PRI

the Primary Rate Interface level of ISDN service, intended for larger users. It includes a number of B-channels and a D-channel. Each carries data, voice, and other services. The D-channel carries control and signaling information.

DSL (Digital Subscriber Line)

a technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines. Assuming your home or small business is close enough to a telephone company central office that offers DSL service, you may be able to receive data at rates up to 6.1 megabits (millions of bits) per second, enabling continuous transmission of motion video, audio. More typically, individual connections will provide from 1.544 Mbps to 512 Kbps downstream and about 128 Kbps upstream. A DSL line can carry both data and voice signals and the data part of the line is continuously connected.

Circuits that Transport Data Only

Frame Relay

a telecommunication service designed for cost-efficient data transmission for intermittent traffic between local area networks (LANs) and between end-points in a wide area network (WAN). Frame relay puts data in a variable-size unit called a frame and leaves any necessary error correction (retransmission of data) up to the end-points, which speeds up overall data transmission. Frame relay was designed for transmitting analog data such as voice conversations.

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