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Glossary of T1 Terminology
Access Provider
An access provider is a company or an organization, which enables you to access the Internet. To access Internet through access providers, you may be an owner of a single computer system or a part of an organization having many computers. If you access Internet directly through your company account, your company is your access provider. Access providers can be of two types, Internet Service Providers (ISPs), which allows you to connect your computer to Internet and Online Service Providers (OSPs), which provides you independent online content apart from connection you to Internet.
ATM (Asynchronous Transfer Mode)
Asynchronous Transfer Mode is a type of data transmission that allows you to transfer multiple types of data on the same network. The data that can be transferred using ATM can be, voice, video and ordinary data. The data to be transferred is organized into packets and the transmission is not always periodic. This transmission mode is called asynchronous because a cell is processed asynchronously relative to other related cells by allotting a time slot.
Bit Error Rate Test (BER)
The telecommunication Transmission defines Bit Error Rate (BER) to describe the percentage bits that have errors while receiving a data transmission. The error rate test tells you the ratio of total number of error bits received in a transmission. BER is usually expressed as ten to a negative power in exponential form. For example 10^-6 means that one bit out of 1,000,000 transmitted bits was in error.
Basic Rate Interface (BRI)
Basic Rate Interface is an Integrated Services Digital Network (ISDN) is a multipurpose user interface standard. BRI has the capability to operate upon two clear 64-kb/s channels and one clear 16-kb/s channel (2B+D). The 64 kb/s B channels may be used to carry voice, circuit-switched data, or packet data and one 16 kb/s D channel can be used to carry signaling and packet information. The BRI service is provided from a Digital Line Unit (DLU).
Carrier
Carrier is a sinusoidal component of a modulated wave in a frequency-stabilized system. A carrier signal is a signal whose frequency is modulated to carry analog or digital signal information. For example an FM radio transmitter modulates the frequency of a carrier signal and the receiver processes the carrier signal to extract the analog information
Channel Service Unit (CSU)
Channel Service Unit is a type of interface, which enables you to connect your computer terminal to a digital medium. Just as you use a modem connect your computer to analog medium, you use CSU to connect to a digital medium. To use CSU, you need to provide transmit and receive logic for incoming signals. CSU allows you to use your own equipments to retime and regenerate the incoming signals.
Dedicated Service
A dedicated service refers to the communication network dedicated to a group, individual or a specific purpose. The dedicated service provides users a set of functions to authorize users. Dedicated services are usually specified in a communications format, such as voice, digital data, facsimile, or video.
Direct Inward Dialing (DID)
Direct Inward dialing is a system, which directly routes the incoming telephone calls to the PBX to reach a specific PBX extension. A DID system does not use human intervention to direct the calls to the target location. When an incoming call arrives the call is routed to the addressee without being passed to an intermediate device.
Digital
Digital signals as the name suggests are digit based. The digital signals are represented in the form of binary (zero or one) signals. The digital signals are different from electrical signals, which can be represented using voltage, frequency, and amplitude. Digital signals are capable of providing high transmission speed with low error rate. The digital signals can be detected and regenerated but cannot be amplified like electrical signals.
Digital Signal 0 (DS0)
In T-carrier, Digital Signal 0 (DS0) is a dedicated, point-to-point private line service, which is capable of supporting voice, video, analog and digital data. DS0 can transmit data with the speed of 2.4, 4.8, 9.6 and 56/64 kbps.
Data Service Unit (DSU)
Data Service Unit is a standard interface device that is used for digital transmission. DSU is connected from one end to CSU (Channel Service Unit) and from other end to Data Terminal Equipment (a terminal or computer). DSU transmits and receives data. While transmitting data, the transmitting portion of DSU converts the signals to bipolar pulses, which can be easily transmitted over digital facility. While receiving data, the receiving portion of DSU extracts timing information and regenerates the mark and space information from the received bipolar signal.
Data Terminal Equipment (DTE)
Data Terminal Equipment is a device that controls data communication between computers. It enables you to send, receive or send and receive data at the same time from your computer. DTE is an interface that is used by your computer to exchange data with a modem or other serial device. DTE includes terminals, computers, protocol converters, and multiplexers.
Fiber Axis
The Fiber Axis refers to the longitudinal center of symmetry of an optical fiber. It is actually the mechanical centerline through the core of an optical fiber. In Fiber Axis the locus of points are determined by the centers of mechanical symmetry of the outside diameters of fiber cross sections sampled continuously along the length of the fiber.
Fiber Optics
Fiber Optics is a data transmission technology that transmits data digitally using glass or plastic fibers (also called threads). This technology is more efficient and expensive and fragile as compared to metal cables. It is capable of providing more bandwidth as compared to metal cables.
Frame Relay
Frame relay is a telecommunication service based on packet-switched technology. It is a cost effective and faster way to transmit data between local area networks (LANs) and between end-points in a wide area network (WAN). Frame relay sends the information in packets called frames. Each frame contains the necessary destination information. Frame relay leaves any necessary error correction or the responsibility to retransmit data to the end-points.
Integrated Services Digital Network (ISDN)
ISDN (Integrated Services Digital Network) is a type of connection that is used to transmit digital signals over ordinary telephone line. ISDN is capable of transmitting data at much faster rate as compared to the data transfer done using modems. It can transmit voice, data and images at speeds up to 2Mbit/s. It provides two types of services, Basic Rate Interface (BRI) and Primary Rate Interface (PRI). The BRI is intended for the home and small enterprise, and the PRI is made for larger users.
Inverse Multiplexing
Inverse Multiplexing is a technology, which speeds up the data transmission to the other end by dividing the data stream into multiple small streams. After creating multiple concurrent streams, it passes the streams to separate channels such as T1 and E1 lines. On the other end these streams are constructed again to form an original stream. The multiplexing is usually used when you need to keep transferring data between local area network (LAN) and wide area network (WAN) through a slower line such as T-1 (1.544 Mbps).
Loop
A loop is a computer programming technique used by a programmer to execute a set of statements till the specified condition is reached. Loops can be used in situations where you want the end user to provide certain data, or you want to repeat the process again and again till the counter reaches the prescribed number. If the loops are not planned properly, you may end up creating a loop, which will never terminate.
Loop Back
The Loop Mack is a method to test the transmission through access lines. This testing method is performed from the serving switching center and does not require any human intervention at the served terminal.
Multiplexer
A multiplexer is a device that converts the data signals fragmented into various streams, into a single original stream. For example a multiplexer is capable of combining output from several different users connected by modem into one data stream and send the stream to the other end using high speed leased line.
Network Address Translation (NAT)
Network Address Translation (NAT) is used when you have a big network connected to Internet. In such a scenario you need to translate the Internet Protocol address (IP address) used within your network to a different IP address known within another network, such as Internet. NAT is usually a part of router in a corporate firewall.
Packet
A packet is a chunk of data routed over a network between two end points. This chunk of data contains the source and destination information for the data it contains. The network protocols such as Transmission Control Protocol (TCP) breaks a file into packets to route the data smoothly over the Internet. After all the packets of a file reach the destination location, the packets are reassembled into the original file (by the TCP layer at the receiving end). A file can be any file such as e-mail message, HTML file, Graphics Interchange Format file, and Uniform Resource Locator request file.
Packet-switched Networks
Packet-switched Networks are the type of networks, where the information that needs to be transmitted is broken into small packets. Each packet traveling over a network contains the source and destination information of the data it contains. The Packet-switched Networks allows the same data path to be shared among many users in the network. This type of communication between sender and receiver is known as connectionless.
Private Line
A private line is a dedicated line used to connect the equipments, such as computers and terminals at both ends. To connect equipments the dedicated circuits are used. A private line generally uses two local loops and an IEC circuit and does not provide switching capability.
Private Branch Exchange (PBX)
A PBX (private branch exchange) is a private exchange in an organization, as the name suggests. It enables you to share a set of external telephone lines among the local lines inside the organization. A PBX is owned and operated by the enterprise and not by the telephone company, who may be the final suppliers of the external telephone lines. Initially the PBX used to use analog technology but these days digital technology is used.
Point Of Presence (POP)
Point Of Presence (POP) is an Internet access point, which provides a physical access location interface between a local exchange carrier and an Inter-exchange Carrier. POP has a unique IP address. Telecommunication companies use POP to terminate a subscriber's circuit for long distance service or leased line.
Synchronization
Synchronization is a method of transmitting data serially from one end to another. The receiving end expects data to appear in the same order as it was sent. For example the receiving end must know where one character ends and the next begins. If synchronization does not happen, the receiving end would perceive data simply as a series of binary digits with no relation to one another.
T1 Line
The T1 lines are the high bandwidth connection telephone lines. These lines can handle 24 voice or data channels at 64 kilobits per second, over two twisted pair wires. These lines are used when you need to handle heavy telephone traffic or you need to handle high speed Internet access for your computer networks. Normally small and medium-sized companies with heavy network traffic use T1 lines. T1 lines are capable of sending and receiving very large text files, graphics, sounds, and databases very quickly.
T1 Internet
T1 Internet refers to the Internet connection, which is achieved using T1 line. The T1 lines provide high bandwidth and therefore the Internet Access using T1 line is very fast. The T1 Internet is very expensive and is not a realistic solution for small and low-demand Internet users. Internet T-1 is a fast, reliable dedicated online service for big networks. It runs at 1.544 Mbps, fast enough for 25 or so simultaneous users.
Trunk
The trunk refers to a circuit that exists between switchboards and other switching equipments. A trunk circuit may extend between central office switching equipment and information origination/termination equipment.
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