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Appendix A
Glossary
- A3
- ISO page size 11.9" x 16.5" (303 mm x 420 mm); one of the available NaturalFax page width formats.
- A4
- ISO page size 8.25" x 11.6" (210 mm x 297 mm); one of the available NaturalFax page width formats.
- AG
- Natural MicroSystems' Alliance Generation product line of telephony and voice processing hardware.
- B4
- ISO page size 10" x 14" (255 mm x 353 mm); one of the available NaturalFax page width formats.
- CED
- CallED tone; the 3-second 2100 Hz tone that a called fax terminal places on the line to indicate that the called station is a fax terminal. See also CIG, CNG, T.30.
- CIG
- CallInG subscriber identification; used in fax polling by the calling fax terminal to identify itself. The CIG is defined by ITU T.30 as the calling station's international telephone number. It can contain up to 20 characters. See also CED, CNG, T.30.
- CNG
- CalliNG tone; the 0.5 second, 1100 Hz tone placed on the line every 3 seconds until CED is received. The CNG tone indicates a fax terminal is calling. See also CED, CIG, T.30.
- CSI
- Called Subscriber Identification; an optional frame used by the called fax terminal to deliver its international telephone number. The frame can contain up to 20 characters. See also Group 3 fax, T.30.
- CT Access
- Natural MicroSystems' development environment for telephony applications.
- CTA context
- In CT Access, an entity that organizes services and accompanying resources around a single processing context. Usually represents an application instance controlling a single telephone call. Some contexts are not associated with a call; an application performing voice conversions does not require a telephone line.
- ctahd
- The handle returned by ctaCreateContext that identifies a specific CTA context. See also CTA context.
- ctaqueuehd
- A handle that uniquely identifies a CT Access event queue. It provides access to events from one or more CTA contexts.
- DCN
- DisCoNnect frame; a disconnect message sent by the calling fax terminal to the remote fax terminal before the calling fax terminal releases the call. The calling fax terminal can release the call as soon as it sends the DCN frame; it does not need to wait for a response from the remote terminal. See also Group 3 fax, T.30.
- DCS
- Digital Command Signal; the setup command used by a calling fax terminal in response to Digital Identification Signal (DIS). The DCS determines the attributes of the fax transmission to follow (transmission speed, resolution, etc.). See also DIS, Group 3 fax, T.30.
- DIS
- Digital Identification Signal; used by the called fax terminal to communicate its capabilities to the calling fax terminal. See also DCS, Group 3 fax, T.30.
- document
- In NaturalFax, the image entity to be transferred. It is contained in a single file, and can contain more than one page. Documents to be transmitted by NaturalFax must be in TIFF-F format. Documents received by NaturalFax are stored in TIFF-F format. See also TIFF-F.
- document queue
- A NaturalFax data structure that contains references to documents. A document queue must be either a send queue or a receive queue. Only send queues can be sent, and only receive queues can be used to receive documents.
- DTC
- Digital Transmit Command; used by the calling fax terminal to poll the called fax terminal. See also polling.
- ECM
- Error Correction Mode; for fax transmission, a T.30 option which can be used to correct transmission errors. The fax receiver uses checksum information to verify that the image data received matches what was transmitted. If it does not match, the receiver can request retransmission of a portion of the data. This option is useful when noisy telephone line conditions are expected.
- events
- In CT Access, data structures that contain notification of certain conditions or state changes. Events can be sent from the hardware or from another software module to the application program. All events are represented as C data structures. The event structure contains information about the specific event, including a timestamp, associated CTA context, specific data, error codes, or reason codes. For example, when a voice play operation completes, a completion event is returned to the application.
- fax machine or fax terminal
- Facsimile transfer machines for sending and receiving images and written material over a telephone line. Almost all fax machines today use the CCITT Group 3 protocol. A higher performance protocol, CCITT Group 4, is available for ISDN. See also G3FE, Group 3 fax.
- fax session
- According to the ITU T.30 specification, and as used in NaturalFax, the portion of a fax transfer operation which begins with the called fax terminal sending its capabilities (Phase B) to the calling application or fax terminal and ends with the calling fax terminal commanding a disconnect (Phase E). See also Group 3 fax, Phase B, Phase E, T.30.
- G3FE
- Group 3 fax equipment. See also Group 3 fax.
- Group 3 fax
- A fax protocol published in 1980 by the ITU. Group 3 protocol is specified in several standards: T.4 and T.6 specify the image format, T.30 specifies the session management protocol which supports the establishment of a fax transmission. Since Group 3 protocol is specified for the switched analog network, and it is an all-digital procedure, it must use modems. See also fax machine or fax terminal, ITU, T.4, T.6, and T.30.
- International Telecommunications Union
- See ITU.
- ITU
- International Telecommunications Union; an international standards body for telecommunications.
- IVR
- Interactive Voice Response; a telephony application in which callers interact with a program using recorded or synthesized voice prompts, DTMF digits, or speech recognition to query or deliver information.
- jitter
- A lack of synchronization caused by varying transmission delays over a given connection.
- jitter buffer
- A mechanism for receiving data over a connection with jitter and manipulating the data into a synchronous stream of data without jitter. A jitter buffer can be implemented in many ways. A simple jitter buffer can be implemented as a fixed block of allocated memory. To implement a more robust, flexible version, create a linked list of data blocks dynamically, as needed, which provides a jitter buffer of virtually unlimited size.
- MMR
- Modified Modified Read; an encoding format for fax documents than enables the transmitter or receiver to perform additional error checking and data validation. It is more compact than MH encoding or MR encoding for most images.
- NMS
- Natural MicroSystems Corporation.
- Non-Standard Facilities Frames
- The Group 3 fax standard, ITU T.30, allows non-standard frames (a frame with contents that are not specified by T.30) to be transmitted with most negotiations. A non-standard frame begins with the country code of the manufacturer, the manufacturer's code, and any additional ASCII information (limited by allowable transmission time of three seconds). The non-standard frame transmitted by a remote fax terminal will only be read if the first three bytes match the country code and manufacturer's ID parameters for the local fax terminal. T.30 defines the following terms for non-standard frames:
- NSS (Non-Standard Set Up), a frame sent by the called fax
terminal in response to the calling fax terminal's DCS frame (the
DCS frame was sent in response to the called fax terminal's DIS
frame).
- NSC (Non-Standard facilities Command), a frame sent by the
calling fax terminal to command the called fax terminal to send (a
poll).
- NSC
- Non-Standard facilities Command frame; a non-standard frame as specified by the ITU T.30, the Group 3 fax standard, sent by the calling fax terminal to command the called fax terminal to send (a poll).
- NSF
- Non-Standard Facilities frame; a non-standard frame as specified by the ITU T.30, the Group 3 fax standard, sent by the calling fax terminal in response to the called fax terminal's DIS frame. See also DIS.
- NSS
- Non-Standard Set Up frame; a non-standard frame as specified by the ITU T.30, the Group 3 fax standard, sent by the called fax terminal in response to the calling fax terminal's DCS frame (the DCS frame was sent in response to the called fax terminal's DIS frame).
- Phase A
- The call setup phase of a T.30 protocol fax session. See also Group 3 fax, T.30.
- Phase B
- The pre-message procedure for identifying and selecting call-specific facilities of a T.30 protocol fax session. See also Group 3 fax, T.30.
- Phase C
- The image transfer phase of a T.30 protocol fax session. See also Group 3 fax, T.30.
- Phase D
- The post-message procedures (EOM and multi-document procedures) of a T.30 protocol fax session. See also Group 3 fax, T.30.
- Phase E
- The call release phase of a T.30 protocol fax session. See also Group 3 fax, T.30.
- polling
- During a fax polling operation, the calling fax terminal requests that the called fax terminal send documents to the calling fax terminal. This is also known as turnaround polling.
- PRI
- PRocedure Interrupt; a signal to the remote fax terminal which requests the remote fax terminal to permit operator interaction. A PRI signal is used to request that the remote fax terminal allow operator intervention, such as voice communications over the handset, and not hang up the call at the end of a fax session.
- receive queue
- A NaturalFax document queue for receiving documents transmitted from one fax terminal to another. A receive queue must have an allocated entry for each document to be received. Only names of files that do not exist can be enqueued in a receive queue; the file name may not be NULL. See also document queue, send queue.
- receive training zeros
- An indication of the amount of zero symbols received during the TCF portion of a fax call. See also TCF.
- send queue
- A NaturalFax document queue structure for document files to be sent from one fax terminal to another. A send queue can only be used to send a queue of documents (the NaturalFax application is acting as the transmitter). It cannot be used to receive document files when the NaturalFax application is acting as the receiver. Only files that already exist can be added to a send queue. A unique file can be placed in multiple send queues simultaneously. See also document queue, receive queue.
- signal to noise ratio
- The ratio of signal to noise, reported in dB. Indicates line quality.
- SNR
- See signal to noise ratio.
- store-and-forward
- An application that receives data, such as a fax image or voice data, stores it temporarily, and forwards it to its final destination. Typical fax store-and-forward applications include "never busy fax" applications, and applications which transmit a fax image to a remote fax gateway over the IP network.
- 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.
- T.37
- Describes an end-to-end fax transmission from the Internet to a G3 device using e-mail as the transport. The ITU-T document for a T.37 session describes the supported format and required addressing conventions.
- TCF
- Training Check Frame. A known sequence of scrambled zeros sent by the transmitter during negotiation. This signal is used as a test to determine if a fax can be sent at a particular data rate. See also receive training zeros.
- 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.
- TIFF-S
- A class of TIFF file, designed for simple interchange of black and white facsimile. TIFF-S files are 1D encoded, low resolution, A4 pagewidth, and have no optional fields.
- training
- 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.
- universal port
- A port that can use any combination of IVR or fax functions. If a system is configured for universal ports, the application can use any combination of IVR functions such as voice play, voice record, tone detection, and tone generation with fax transmit or fax receive functions. Switching between these two functions within a single phone call is supported in a universal port configuration.
- V.17
- The 7200/9600/12000/14400 bps modem which is used for Group 3 fax.
- V.21
- The 300 bps modem used for Group 3 fax negotiations.
- V.27ter
- The 2400/4800 bps modem which is used for Group 3 fax.
- V.29
- The 7200/9600 bps modem which is used for Group 3 fax.
- V.33
- The 14400/12000 bps modem which is used for Group 3 fax.
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