1.1 NaturalFax Overview

1.1.1 NaturalFax Capabilities

1.1.2 NaturalFax System Architecture

1.2 Fax Application Overview

1.2.1 Natural Access Components

1.2.2 Preparing the Hardware Environment

1.1 NaturalFax Overview

The NaturalFax Developer's Reference Manual provides

• Detailed information about developing NaturalFax applications under Natural Access.

• A complete reference for the NaturalFax API.

• Information on the NaturalFax demonstration programs and utilities.

This manual is targeted to developers of fax applications who are using Natural Access. This document defines telephony terms where applicable, but assumes that you are familiar with telephony concepts and the C programming language.

1.1.1 NaturalFax Capabilities

NaturalFax is a C function library component of Natural Access that provides fax functionality. Use NaturalFax to produce fax server products for enterprise fax applications, IP telephony gateways, and large scale fax service provider systems. Applications include LAN fax, fax broadcast, fax-on-demand, store-and-forward, and realtime fax-over-IP data networks. NaturalFax applications can transmit and receive Group 3 facsimiles at rates of up to 14,400 bps.

NaturalFax supports the following features:

• Enhanced Group 3 fax features such as

• 1D, 2D, and MMR encoding

• Error correction mode (ECM)

• Low, high, and superhigh resolutions

• Standard page width formats

The T.37 format, specified as 1D encoding, low resolution, and A4 pagewidth

The ability to convert documents into different formats, resolutions, or encodings online (on-the-fly) or offline

The ability to poll a remote fax terminal and request that it transmit a fax.

For more information about the Group 3 fax standard, see Appendix D.

1.1.2 NaturalFax System Architecture

NaturalFax runs on NMS hardware that consists of various telecommunications interfaces, a high-speed controller, and an array of DSPs. The following boards support NaturalFax:

• AG Quad, CompactPCI AG Quad

• QX 2000 (runs under Windows NT and Windows 2000 only)

• AG 2000, AG 2000C

• AG 2000-BRI (runs under Windows NT and Windows 2000 only)

• AG 4000, AG 4000C

• CG 6000, CG 6000C

• CG 6100C

On AG and CG boards, the fax modems run on TI C5x and C54x DSPs, sharing them with other telephony algorithms such as voice record and play. The T.30 fax communication protocol runs on the AG or CG board controller and host processor. This sharing of DSP and controller resources contrasts with traditional chip-per-port designs, and provides the highest density and lowest cost-per-port fax boards and systems.

In the QX family of boards, NaturalFax runs on the TI C549 DSP, which serves both as a DSP resource and board controller. The simplified architecture of the four port QX design leads to high performance at a lower cost.

1.2 Fax Application Overview

A NaturalFax application uses Natural Access functions to control the PSTN and NaturalFax functions to manage fax sessions and related tasks. Natural Access functions

• Initialize and tear down the application.

• Perform call control.

NaturalFax functions

• Build and destroy document queues.

• Transmit or receive faxes.

• Perform image format conversions.

• Monitor fax session status.

• Monitor fax document status.

A fax session begins when a transmit or receive operation is initiated, and ends when the application receives the corresponding NaturalFax DONE event. A document queue contains a list of one or more document files (the document files must be in TIFF-F or TIFF-S format). NaturalFax functions operate on document queues, not on individual files. You must use document queues for all fax operations, including transmitting and receiving single documents.

Figure 1 shows how Natural Access and NaturalFax are used in a basic NaturalFax application:

Figure 1. Fax Application Overview

1.2.1 Natural Access Components

A Natural Access service is a group of logically related telephony functions. The NaturalFax service provides functions for sending and receiving Group 3 faxes.

A Natural Access context organizes services and accompanying resources around a single processing context. A context usually represents an application instance controlling a single telephone call. Some Natural Access contexts are not associated with a call; an operation performing fax file conversions does not require a telephone line.

Note: Only one asynchronous fax operation per context can be active at one time.

A service can only be opened once on an individual context. For example, in order to send faxes using all eight channels of an AG 2000 board, an application needs to create eight Natural Access contexts, and open the NaturalFax service on each context.

An event queue is the communication path from a service to an application (such as NaturalFax). A service generates events indicating certain conditions or state changes. An application retrieves the events from the event queue.

You can alter the characteristics of services by modifying associated parameters. Each NaturalFax parameter structure has default values sufficient for most configurations. NaturalFax applications typically need to set the subscriber ID (the telephone number) to comply with FCC or other local regulations, but may not need to modify other parameters.

Natural Access manages parameters for services on a context basis. The context maintains a copy of the parameters for all services opened on the context, allowing each fax operation to have its own characteristics. See Appendix B for detailed descriptions of NaturalFax parameters and their default values.

For detailed information about Natural Access, see the Natural Access Developer's Reference Manual.

1.2.2 Preparing the Hardware Environment

You must initialize and load all boards before you can run NaturalFax. Use NMS OAM to perform hardware configuration and initialization. For more information, see the NMS OAM System User's Manual.