Nortel Networks Corporation (Nortel), formerly commonly known as Northern Electric and Northern Telecom, was a multinational telecommunications and data networking equipment manufacturer headquartered in Mississauga, Ontario, Canada. It was founded in Montreal, Quebec, in 1895 as the Northern Electric and Manufacturing Company. Until an antitrust settlement in 1949, Northern Electric was owned principally by Bell Canada and the Western Electric Company of the Bell System, producing large volumes of telecommunication equipment based on licensed Western Electric designs.
Digital Multiplex System (DMS) is the name shared among several different telephony product lines from Nortel Networks for wireline and wireless operators. Among them are the DMS-1 Rural/Urban digital loop carrier, DMS-10 telephone switch, the DMS SuperNode family of telephone switches, and the S/DMS optical transmission system.
The name comes from the fact that Switch56 carried 56 kbit/s of data on its 64 kbit/s lines, as opposed to most systems, including ISDN, where the entire 64 kbit/s bandwidth was available for data. The speed was a side effect of Nortel using a 2-wire cable to carry both voice and switching commands, as opposed to other systems where the command data was carried on a separate set of low-speed lines. Switch56 "folded" the two sources of data into one, placing a single bit from the command channel onto the end of every 7 bits of data, similar to the original T-carrier supervision scheme. This data was split out at the "far end" as 56 kbit/s and 8 kbit/s subchannels.
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls.
Switch56 was built on top of the basic Nortel hardware to allow computers to put data into the existing telephony network. Although slow compared to even contemporary systems, Switch56 allowed network traffic to flow not only within an office like other LAN systems, but between any branch offices that were connected using a Nortel PBX like the Meridian Norstar. This was a much easier option to install than ISDN for most offices, requiring nothing more than a Switch56 bridge to their existing network. For the LAN role new telephone terminals were produced with a RS-232C port on the back, which were then plugged into the user's computer and used with custom software. Although interesting in theory, it appears Switch56 saw little use in this role.
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger geographic distance, but also generally involves leased telecommunication circuits.
The Meridian Norstar, later called Nortel Norstar was a small-office digital [key system] introduced by Northern Telecom. It is based on the same internal design and instruction set as Nortel's earlier SL-1 and DMS systems, allowing it to support features such as integrated voice messaging, automatic call distribution and other features, but possibly supporting a total of up to 192 phones and with limited processing power. In the United Kingdom it is sold by British Telecom, rebadged as the BT Norstar.
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Related Research Articles
Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. It was first defined in 1988 in the CCITT red book. Prior to ISDN, the telephone system was viewed as a way to transport voice, with some special services available for data. The key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system. The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface (BRI), Primary Rate Interface (PRI), Narrowband ISDN (N-ISDN), and Broadband ISDN (B-ISDN).
A 56 kbit/s line is a digital connection capable of carrying 56 kilobits per second (kbit/s), or 56,000 bit/s, the data rate of a classical single channel digital telephone line in North America. In many urban areas, which have seen wide deployment of faster, cheaper technologies, 56 kbit/s lines are generally considered to be an obsolete technology.
A wide-area network (WAN) is any telecommunications network or computer network that extends over a large geographical distance/place. Wide-area networks are often established with leased telecommunication circuits.
Digital subscriber line is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.
Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. It is used when the bit rate of the transmission medium exceeds that of the signal to be transmitted. This form of signal multiplexing was developed in telecommunications for telegraphy systems in the late 19th century, but found its most common application in digital telephony in the second half of the 20th century.
LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer.
Basic Rate InterfaceorBasic Rate Access is an Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for voice-grade telephone service.
As such, an ISDN BRI connection can use the existing telephone infrastructure at a business.
GeoPort is a serial data system used on some models of the Apple Macintosh that could be externally clocked to run at a 2 Mbit/s data rate. GeoPort slightly modified the existing Mac serial port pins to allow the computer's internal DSP hardware or software to send data that, when passed to a digital-to-analog converter, emulated various devices such as modems and fax machines. GeoPort could be found on late-model 68K-based machines as well as many pre-USB Power Macintosh models. Some later Macintosh models also included an internal GeoPort via an internal connector on the Communications Slot. Apple GeoPort technology is now obsolete, and modem support is typically offered through USB.
A digital subscriber line access multiplexer is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques.
ISDN Digital Subscriber Line (IDSL) uses ISDN-based digital subscriber line technology to provide a data communication channel across existing copper telephone lines at a rate of 144 kbit/s, slightly higher than a bonded dual channel ISDN connection at 128kbit/s. The digital transmission bypasses the telephone company's central office equipment that handles analogue signals. IDSL uses the ISDN grade loop without Basic Rate Interface in ISDN transmission mode. The benefits of IDSL over ISDN are that IDSL provides always-on connections and transmits data via a data network rather than the carrier's voice network.
Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Various technologies, at a wide range of speeds have been used by Internet service providers (ISPs) to provide this service.
A leased line is a private bidirectional or symmetric telecommunications circuit between two or more locations provided in exchange for a monthly rent. Sometimes known as a private circuit or data line in the UK.
Hayes Microcomputer Products was a U.S.-based manufacturer of modems. The company is well known for the Smartmodem, which introduced a control language for operating the functions of the modem via the serial interface, in contrast to manual operation with front-panel switches. This smart modem approach dramatically simplified and automated operation. Today almost all modems use a variant of the Hayes command set.
The DMS-100 Switch Digital Multiplex System (DMS) was a line of telephone exchange switches manufactured by Northern Telecom. Designed during the 1970s and released in 1979, it can control 100,000 telephone lines.
Digital access carrier system (DACS) is the name used by British Telecom in the United Kingdom for a 0+2 pair gain system.
A digital subscriber line' ('DSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line service for connectivity to the Internet, which is often called DSL broadband.
A computer network is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections between nodes. These data links are established over cable media such as wires or optic cables, or wireless media such as Wi-Fi.
The 1-Meg Modem in telecommunications was a DSL modem created by Nortel which conforms to the ADSL Lite standard. The 1-Meg Modem was the first xDSL modem to gain approval and registration under FCC Part 68 Rules.
A modem is a hardware device that converts data between transmission media so that it can be transmitted from computer to computer. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used with any means of transmitting analog signals from light-emitting diodes to radio. A common type of modem is one that turns the digital data of a computer into modulated electrical signal for transmission over telephone lines and demodulated by another modem at the receiver side to recover the digital data.
