- T -

T point

The service access point between NT2 and NT1 ISDN equipment. See also NT1, NT2, SAP.

T1

A standard for telephone transmission that multiplexes 24 digital voice channels on a single 1.544 Mbyte/s carrier.

T.4

The standard which defines Group 3 image format for MH and MR encoding. See also Group 3 fax, ITU.

T.6

The ITU standard which defines Group 3 MMR fax protocol. See also Group 3 fax, ITU, MMR.

T.30

The ITU standard which defines the negotiating procedures and session management for Groups 1, 2, and 3 fax. T.30 divides a fax session into five phases, A through E. See also Group 3 fax, ITU.

talker

The timeslot that drives the output for a connection in the CT Access Point-to-Point Switching service. See also connection, listener(s), Point-to-Point Switching service.

talk-over

See barge-in.

talk-off

Mistaking voice input for a DTMF tone.

[Microsoft] TAPI

Microsoft's Telephony Application Programming Interface; a set of functions that enables programming of telephone line-based devices in a device-independent manner, giving personal telephony to users. TAPI supports both speech and data transmission, allows for a variety of terminal devices, and supports connection types and call-management techniques such as conference calls, call waiting, and voice mail. See also WOSA.

TAPI.DLL

The client software module that interacts directly with the Telephony Service Provider by means of the TSPI. The TAPI.DLL exports TAPI to its clients which may be DLLs operating on behalf of applications. See also TSPI.

task

A software operation taking place on a board rather than on the PC host.

task processor

A single DSP chip on a hardware board. Each task processor is configured to run one or more overlays (downloadable DSP software modules).

TCAP

Transaction Capabilities Application Part; an SS7 protocol that provides applications with transaction support over the SS7 network. It enables the exchange of non-circuit related data, such as database queries/responses and remote feature invocation requests, between SS7 signaling points. The TCAP layer relies on both the MTP and SCCP layers for message addressing and delivery.

TCP

Trunk Control Program; a downloadable module which contains the low-level code to interface with an analog or digital trunk running a certain protocol. TCPs are specific to a trunk protocol, for example, one-way inbound with wink start (which is used for DID and DNIS). See also DID, DNIS, loop start (LS), NOCC, wink.

Transfer Control Protocol; a transport layer protocol that offers connection-oriented, reliable, stream service between two hosts. See also transport layer, UDP.

TCP/IP

Transmission Control Protocol/Internet Protocol; the basic communication language or protocol of the Internet. TCP/IP uses the client/server model. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point. TCP/IP and the higher-level applications that use it are collectively said to be "connectionless" because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration). Being connectionless frees network paths so that can be in continuous use. (Note that the TCP layer itself is not connectionless as far as any one message is concerned. Its connection remains in place until all packets in a message have been received.)

The Transmission Control Protocol manages the assembly of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination.

TDM

Time Division Multiplexing; a technique for transmitting a number of separate data, voice, and/or video signals simultaneously over one communications medium by quickly interleaving a piece of each signal one after another.

TE1

An ISDN equipment category; ISDN end-user terminating equipment, class 1, which terminates a single ISDN trunk.

Telephony Services Architecture

See TSA.

Telephone User Part (TUP)

Like the ISDN user part, the telephone user part is an SS7 protocol that allows for the establishment, supervision, and clearing of circuit-switched connections between two SS7 signaling points, such as central office switches. It is used primarily in parts of Asia, South America, and Latin America. Use of TUP is decreasing as it is replaced by ISUP for circuit switching in most parts of the world.

terminus

In the CT Access Switching service, a single access point to a switch block input or switch block output. A terminus is defined in a data structure that contains fields specifying a bus, a stream, and a timeslot.

text-to-speech

A process which converts plain text into audible speech.

TIFF

Tagged Image File Format; a bitmap file format characterized by the use of tags to specify the format of the file.

TIFF-F

A class of TIFF file intended for use in fax applications. TIFF-F format provides the capability to store multipage fax documents in one file.

TIK service

A CT Access service which provides software timer functionality.

time division multiplexing

See TDM.

timeslot

Specifies a particular 64 kbit/s subdivision of a TDM bus stream. Timeslots number from zero (0) to n where n is stream-dependent.

tip

One conductor of a wire pair, designated by T; usually connected to the positive side of a line circuit. The other is called ring, or R. See also ring.

TMS320

A digital signal processor family produced by Texas Instruments and used on AG boards.

toll category

In MFC-R2 and E&M protocols, the digit received by the inbound application that indicates the Group II category of incoming ANI digits. Usually this is the same as the user category, but in some countries it carries the toll category of the call. See also ANI, E&M, MFC-R2.

tone cycle

The time during which a network tone is active and then absent.

tone detector

A precise tone filter that enables an application to detect single or dual frequency tones.

tracemask

Used to determine which trace record categories are active (should be logged).

trace record

Warning, error, or informational message.

trace record category

Group of related trace records.

trace tag

Unique identifier of a trace record.

training (speech recognition)

In NaturalRecognition, the process of building a vocabulary by associating pronunciations with word indices within a vocabulary.

training (fax)

Negotiation between the modems of the called fax terminal and the calling fax terminal in which the fax terminals attempt to communicate and agree on a rate and modem type for image transfer.

transaction

Used in TCAP, provides a context identifier for related messages. A transaction can consist of several separate TCAP messages, so the transaction identifier enables each message to be related to a unique transaction. Many different transactions can be handled simultaneously. See also TCAP.

transitional event

A protocol-independent call control event which causes a transition in a state machine.

translator

An intermediate system that forwards RTP packets with their synchronization source identifier intact. Examples of translators include devices that convert encodings without mixing, replicators from multicast to unicast, and application-level filters in firewalls. See also RTP, RTP packet.

transport address

The combination of a network address and port that identifies a transport-level endpoint; for example, an IP address and a UDP port. Packets are transmitted from a source transport address to a destination transport address. See also IP address, UDP.

transport layer

In the OSI protocol layering model, the transport layer (layer 4) is the layer above the network layer. Protocols for this layer describe methods for maintaining reliable end-to-end communication across a network. See also network layer, OSI.

TRAU

Transcoding and Rate Adapter Unit; a program or process that converts data streams from one form to another (for example, from analog PCM data streams to digital GSM encoded HDLC frames).

tri-stated

The condition of a logic circuit whose output is in the high impedance state. Most electronic logic circuits try to force their output voltage to be either high or low. Some circuits have a third option which is to present a high output impedance, effectively disconnecting them electrically from the output line. This allows multiple outputs to be safely connected to one line, forming a bus.

trunk

A transmission channel connecting two switching machines.

With regard to NMS products, a trunk is defined as the physical interface between the telephone network and the board. It can be used interchangeably with line because it could be connected to either a trunk or a line.

In telephone networks, a trunk is a shared connection between two switches. It differs from a line in that it is not dedicated to one subscriber or extension. Trunks should have good machine-to-machine interfaces. Compared to lines, trunks have different signaling requirements, including possibly billing information.

Trunk Control Programs

See TCP.

trunk signaling

See signaling.

Tru Voice

The Text-to-Speech DSP algorithm (produced by Centigram Communications Corporation) upon which NaturalText is based.

TSA

Telephony Services Architecture; the NMS model of managing telephony and media functionality in computer systems.

TSI

Transmitting Subscriber Identification; used by the transmitting fax terminal to identify itself. Defined as an international telephone number that can contain up to 20 characters.

TSP

Telephony Service Provider. Components used to provide telephony resources to clients of the Microsoft TAPI interface. See also [Microsoft] TAPI.

TSPI

An interface used by a TSP to make its functions available to applications through TAPI. See also [Microsoft] TAPI.

TTS

Acronym and service name for Text-to-Speech converter.

two-wire

In analog telephony, a connection that requires only two physical conductors. See also four-wire.

txalarm

A utility that collects and displays alarm messages from all tasks on a TX series board.