Glossary
T
T—Provides the connection between the NT1 and NT2. Can be internal to or external from the PABX. Provides the connection between the NT1 equipment and the TA or TE-1. Can provide both Primary Rate and Basic Rate services.
TA—Seeterminal adapter.
TCP/IP (Transmission Control Protocol / Internet Protocol)—A multi-layer set of protocols developed by the US Department of Defense to link dissimilar computers across dissimilar and unreliable LANs.
TEI (terminal endpoint identifier)—A unique number that is assigned to an ISDN terminal adapter at subscription time. The TEI is us ed by the central office to identify the various TAs connected to the ISDN network. The TEI number can be fixed (in the range of 0-63), dynamically, or automatically assigned at the CO each time the TA is connected to the ISDN interface and powered up.
TE1 (Terminal Equipment Type 1)—A terminal device with a standard ISDN interface (an ISDN-compatible terminal).
TE2 (Terminal Equipment Type 2)—A terminal device with a non-ISDN interface, such as RS232, RS449, V.35 or X.21. Can be a telephone, data terminal, or voice/data worrkstation, etc.
telecommunication service—A function, such as bearer service and teleservice, offered by an RPOA to its customer in order to satisfy a specific telecommunications requirement. See also ISDN, RPOA, and bearer service.
telematics—User-oriented ISDN information transfer services (e.g., teletex, videotex, facsimile).
Teleservices—A telecommunications service that provides the complete capability for communication between subscribers according to protocols agreed to by RPOAs. A set of ISDN features using communications links, including E-Mail and fax services.
Teletext—A telecommunications service that provides a one-way information retrieval service that uses unused portions of a TV channel bandwidth. A fixed number of text pages are repetitively broadcast for decoding by a decoder at the TV set that can select and display pages. See also ISDN.
terminal—The screen and keyboard device used in a mainframe environment for interactive data entry. Terminals have no box, which is to say they have no file storage or processing capabilities.
terminal adapter (TA)—An ISDN DTE device for connecting a non-ISDN terminal device to the ISDN network. Similar to a protocol converter or an interface converter, a TA connects a non-ISDN device between the R and S interfaces.
tone dialing—One of two methods of dialing a telephone, usually associated with Touch-Tone® (push button) phones. Compare with pulse dialing.
TSR (terminate and stay resident)—A software program that remains active and in memory after its user interface is closed. Similar to a daemon in UNIX environments.
twisted pair wiring—A type of cabling with one or more pairs of insulated wires wrapped around each other. An inexpensive wiring method used for LAN and telephone applications, also called UTP wiring.
Type A: The upstream (USB Type A) connector. A Type A Connector is for those devices on which the external cable is permanently
attached. Connectors for USB come in two designs: the 'A' and 'B' types. Upstream connections (computer, hub input, etc.) areadem using the 'A' type connector, downstream connections (peripherals, hub outputs) are made using the 'B' type connector. The USBspec defines two types of connectors to protect the bus from illegal topologies (e.g., connecting one downstream port back to another, etc.) and to prevent end-user confusion. This allows end users to easily attach the correct connectors to peripherals and ports. Type A Plug and receptacle are to be used for those devices on which the external cable is permanently attached to devices such as Keyboard, mouse and hubs. Series B Plug and receptacle are to be used for those devices that require an external detachable cable such as printers, scanners and modems.
Type B: The uplink (USB Type B) connector. A Type B Connector is for detachable external cables. Allows for double ended cable
assemblies. Connectors for USB come in two designs: the 'A' and 'B' types. Upstream connections (computer, hub input, etc.)madeare using the 'A' type connector, downstream connections (peripherals, hub outputs) are made using the 'B' type connector. The USBspec defines two types of connectors to protect the bus from illegal topologies (e.g., connecting one downstream port back to another, etc.) and to prevent end-user confusion. This allows end users to easily attach the correct connectors to peripherals and ports. Type A Plug and receptacle are to be used for those devices on which the external cable is permanently attached to devices such as Keyboard, mouse and hubs. Series B Plug and receptacle are used for devices that require an external detachable cable such as printers, scanners and modems.
U
U reference point—A twisted-pair subscriber loop that connects the LT to the NT1. Normally a 2-wire BRI or PRI line is used, but a 4-wire BRI can also be used. In the US, the U Reference Point marks the separation point between CPE and the network.
UHCI (Universal Host Controller Interface): The USB Universal Host Controller Interface. All transfers on the USB are initiated by the host system’s host controller. The host controller is responsible for controlling traffic on the USB and can be appropriately programmed to transfer data to and from USB devices. This is typically a PCI device that can be programmed to run a given schedule of transfers on the USB and bus master the results into memory for processing by the host software. There are currently two standards for host controllers: OpenHCI (OHCI or Open Host Controller Interface) and UHCI (Universal Host Controller Interface). Both these standards define register level interfaces of the host controller to PCI bus. Bandwidth allocation over the USB is software managed and is done by the programming of the host controller.
