A WWW-assisted fax system for Internet fax-to-fax communication
Chong, L.K.S., Hui, S.C., Yeo, C.K., & Foo, S. (1998). World Wide Web Journal, 1, 209-219.
A WWW-assisted fax System for Internet fax-to-fax communication
L. S. K. Chong, C. K. Yeo, S. C. Hui and S. Foo
Nanyang Technological University, School of Applied Science Nanyang Avenue, Singapore 639798
Abstract
This paper describes a WWW assisted fax system (WAX) that is developed to provide reliable and enhanced Internet fax-to-fax communication. It integrates the easy-to-use WWW interface with conventional faxing procedures, resulting in an Internet fax system which not only circumvents the cost of long distance fax charges but also adds enhanced functionality not otherwise possible. The WAX sys tem comprises two gateways, namely, the Fax-In and the Fax-Out Gateways. The Fax-In Gateway accepts fax messages over Public Switched Telephone Network (PSTN) and stores them in a transit database. The system interfaces with the user over the WWW to provide access to his stored faxes, with the basic ability to send them out over the Internet to recipients. The Fax-Out Gateway receives fax files from the Fax-In Gateway through the Internet and transmits them out to the intended recipients via the local PSTN. WAX users do not require any additional hardware except for a fax machine and a personal computer with Internet connectivity to gain access to WAX via any WWW browser.
Keywords: World Wide Web, fax communications, Internet faxing, fax-to-fax, fax
machines.
1. Introduction
Communication possibilities over the Internet are becoming a reality with increasing available bandwidth and worldwide coverage. This has given rise to the convergence of conventional Public Switched Telephone Networks (PSTNs) and the Internet to form the fabric for cheap and economical communications [Dialogic Corporation 1997]. The facsimile (or fax) message, given its digital image and one-way nature, is a suitable candidate for transportation over the Internet using reliable store-and-forward routing. Internet fax communication allows users worldwide to exchange fax messages without incurring the high costs associated with international toll charges. This is particularly important to businesses, as the fax is a popular tool for communicating with geographically dispersed subsidiaries, clients and suppliers. Using the Internet, transcontinental faxing is achieved at the mere costs of local telephone calls and nominal Internet connectivity charges.
Most of the existing Internet faxing systems offer the basic mail-to-fax capability [Gulfnet Kuwait 1998; Malamud and Rose 1993a,b,c; TPC 1993; UIC 1998], which allows
users to send email to a fax machine. Some other systems [FaxMail Ltd. 1998; Interpage Inc. 1998; TPC 1998] offer web-to-fax capability allowing users to send a fax from the World Wide Web (WWW). Both systems restrict the sender to composing messages on a computer. Although convenient in certain situations, this does not emulate traditional faxing where faxes are sent from standalone fax machines. As fax machines are still widely in use, it is necessary to provide support for the Internet transmission of faxes directly from one conventional fax machine to another. Fax-to-fax systems [FaxSav Inc. 1998; FaxMate Inc. 1998] have been developed for supporting such end-to-end Internet faxing.
In contrast to Internet fax-to-fax communications, traditional faxing does not require a destination addressing method to capture the destination fax numbers and related information from the sender. Traditional faxing is a simple "dial and send" procedure where the sender directly calls and faxes to the receiving fax machine. The use of the Internet as a transitive transportation mechanism requires the use of intermediate gateways, which in turn, must know about the intended faxing destinations. Traditional faxing was not designed in preparation for Internet faxing, and hence cannot provide a transparent method in supporting these extra procedures. Therefore, one of the challenging issues of Internet fax-to-fax communications is the design of an effective method for destination addressing to ensure that fax messages get successfully sent through the Internet. With an effective design, conventional fax users should be able to migrate effortlessly onto the Internet.
Different destination addressing methods such as Dual Tone Multi-Frequency (DTMF), Voice Recognition (VR) and Optical Character Recognition (OCR) have already been discussed [Yu and Tseng 1997]. In this paper, a method that integrates convent ional faxing with the familiar World Wide Web (WWW) is proposed. Such a WWW-assisted system known as WWW-assisted Fax (WAX) has been developed at the School of Applied Science, Nanyang Technological University, Singapore.
This paper is organised as follows. Section 2 introduces Internet end-to-end (fax-to-fax) systems and discusses the different destination addressing methods and fax transportation mechanisms available. Section 3 gives the system overview of WAX. The system architecture of WAX is presented in section 4. Section 5 evaluates the WAX system by comparing it with other systems. Finally, the conclusion is given in section 6.
2. Internet Fax-to-Fax Systems
Receiver Fax Machine Fax-Out
Gateway Internet Fax Delivery Fax
The Internet
PSTN
Sender
Fax Machine Fax-In Gateway Fax
PSTN
Figure 1 shows an Internet fax-to- fax system. As shown, the fax message begins and ends at conventional fax machines, similar to traditional faxing. However, gateways are involved to provide the mechanism to transport the message through the Internet instead of international telephone lines. The gateways communicate with the fax machines using the same standard fax protocols [ITU 1988; ITU 1996b] that are used in daily fax communications.
The use of a fax-to-fax system to establish a logical connection from a sender to a receiver requires a two-step connection set-up approach, unlike conventional faxing where the sender directly connects and faxes to the receiver. The first step involves calling the local Fax-In Gateway. The second step requires the user to specify the actual receiver's fax number. This number should typically be an International Direct Dialling (IDD) number or if used within a company, could contain an inter-company country code. The Fax-In Gateway will then route the fax messages through the Internet to an appropriate Fax-Out Gateway which will subsequently transmit the fax to the receiver’s fax machine through its local phone network.
Two issues are important in the design of an Internet fax-to-fax system. They are the destination addressing method and the fax transportation method. Internet fax-to-fax systems require an addressing method to capture destination information from the user in order to be able deliver the fax message to the intended recipient. The challenge is to design a friendly user interface that would make Internet faxing as easy and as similar to traditional faxing as possible. A robust fax transportation method is also needed to deliver the fax from the Fax-In Gateway to the Fax-Out Gateway efficiently and reliably.
2.1 Destination Addressing Methods
Destination Addressing Methods refer to the way the destination address can be specified by the sender to the Fax-In Gateway. The fax sender will be provided with an interface to specify a destination for his fax. Typically, the address would be in the form of an IDD number. Different addressing methods have been designed in efforts to port faxing onto the Internet as elegantly as possible. In this section, some of the more prevalent approaches that have been used in current work will be discussed. These are Dual Tone Multi-Frequency (DTMF), Binary File Transfer (BFT), Voice Recognition (VR) and Optical Character Recognition (OCR).
DTMF is by far the most popular destination addressing method used when interaction over a phone line is required [Yu and Tseng 1997]. It has already been used extensively in areas like airport information, messaging, on-line product inquiry and other such automated systems. Its popularity is largely based on the universal acceptance of the DTMF touch-tone phone. Different DTMF tones are generated when any of the 12 ('0' to '9', '#' and '*') buttons are pressed on a touch-tone keypad. The Fax-In Gateway must be able to detect the DTMF tones. The sender interacts with the gateway using DTMF as follows. The system will initia lly prompt the user using a pre-recorded or computer-generated voice message such as “Please enter the destination address and press hex”. Upon hearing this, the user should enter the necessary DTMF string to specify the IDD fax number of the destination. Subsequently, the user can begin faxing.
VR systems monitor human analog voice signals and attempt to interpret them using a variety of techniques [Dragon Systems Inc. 1982]. These range from simple lookup and compare methods to complex approaches involving neural networks. One of the goals of VR is
to eliminate the requirement of DTMF touch-tone phones when accessing on-line telephone information services. Such a provision is required with users who do not possess touch-tone phones, or who are handicapped. VR gives these users the same ability that DTMF offers, which is a method of responding in interactive phone sessions. The operation steps involved will be exactly the same as DTMF systems except that voice input is used instead of DTMF. The user will simply give the IDD fax number of the destination as voice input. Using speech, VR offers an alternative to the 12-digit vocabulary limit of DTMF. However, considering the inherent complexities and inaccuracies of a VR system, DTMF might prove to be more reliable, especially for the simple need of capturing destination fax numbers.
BFT is a standard [ITU 1996a] that allows for the transfer of binary files using the ITU-T.4 fax protocol. BFT does for faxing what MIME (Multi-purpose Internet Mail Extensions) [Borenstein and Freed 1993; Moore 1993] does for Internet mail. Patel, Henderson and Georganas [Patel et al. 1994] have demonstrated the possibility of using BFT to transfer MIME mails via fax. For BFT, a computer must be used for the packaging of binary files for encapsulation into a single BFT file. These component files can contain any form of data, ranging from images, audio, and application files. BFT treats all these as native binary data. Associated with every fax file is a single header file, which can contain an ad-hoc combination of fields to hold information specialised for different needs. The vital key to using BFT as a destination addressing method is its use of this header to embody the destination addresses. The Fax-In Gateway would have to de-package the BFT file and extract this knowledge by looking at the respective field within the header.
To reduce the need for intervention during Internet fax transportation, OCR allows a fax sender to include the destination information within the faxed document for extraction and recognition. The addressing information could be hand-written or typed, depending on the capacity of the OCR engine [Garris et al. 1995]. With the OCR addressing method, the first page of an incoming fax is typically used as an addressing page. This reduces the need to exhaustively scan all incoming pages. To extract the destination information from this addressing page, a variety of different techniques can be used. These include the use of pre-formatted forms and document image processing [Hui et al. 1997]. Once extracted, Internet faxing can take place without any further intervention.
This paper introduces a method that integrates the conventional faxing with the use of the WWW. The solution does not require any specialised hardware, except for off-the-shelf fax modems and personal computers with Internet connectivity. The WWW, with its spreading global coverage and intuitive layout, is an ideal user interface that has proven to be popular and easy to use. It enables enhanced flexibility and functionality, which cannot otherwise be achieved conventionally or even by other Internet faxing systems.
2.2 Fax Transportation Methods
As the fax communication protocol cannot tolerate packet loss or delay, real-time Internet delivery is still somewhat unachievable given the current Internet packet loss and delay rates. The alternative store-and- forward method is more reliable, albeit the introduction of a transition delays. Supporting transportation methods such as electronic mail and direct file transfer can be used to achieve delivery between the gateways.
The electronic mail system, using the Simple Mail Transfer Protocol (SMTP) [Postel 1992], provides a well-established mechanism for fax delivery. However, mail messages can be
lost or delayed (up to a few hours or days) due to faulty or heavily overloaded SMTP servers. In contrast, if all gateways were directly connected to the Internet, a Fax-In Gateway should be able to directly access all the Fax-Out Gateways using unique IP addresses. File Transfer Protocol (FTP) [Postel 1981] or a Transmission Control Protocol (TCP) based file transfer protocol can then be used to transfer the fax image files directly between the Fax-In Gateway and the Fax-Out Gateway with minimal latency. TCP inherently ensures reliable and error-free data transmission and reception between two nodes and is an important component of the Internet’s group of protocols. This latter form of delivery is preferred since it performs better in terms of transport efficiency and reliability.
3. System Overview PSTN Receiver Fax Machine Fax-Out Gateway 6: Fax The Internet PSTN Fax-In Gateway Sender
Fax Machine Transit Fax
Database Web Server 2: Transit Fax Storage 4: Retrieval 1: Fax 0: Registration & 3: Form Submission 5: Internet Fax Delivery Same user WWW Browser
Figure 2. Overview of the WAX System
Figure 2 shows an overview of the WAX process. To be able to use the fax-to- fax service, the user has to firstly register (step 0) his fax machine using WAX’s registration page. With WAX, the Web server and the Fax-In Gateway can be located in the same machine. During registration, the user provides his fax machine's terminal identifier (TID) which is a short identification string that every fax machine has and can be custom set. The TID typically contains a fax number or company name that can be formed using any combination of alphabets and numbers. The user also needs to provide a password, which he will use to access his faxes in transit. Upon the completion of registration, the user can begin to use the fax-to-fax service. The system will accept all faxes originating from the registered fax machine, as long as its TID remains unchanged.
The user can fax his documents to the system (step 1). This is a normal fax transmission and can be done using any conventional fax machine. This fax machine's TID must however conform to the one registered. Once the fax has been received by the system, it is stored in the transit fax database (step 2). The user can leave as many faxes as he would like in transit, limited only by the policy implemented by the system operator and the database capacity. Faxes in transit are subsequently launched (i.e. sent off) by assigning them an address which is typically an IDD number (step 3). The user does this by logging on to WAX's Fax Launch page entering his machine's TID and password. WAX will search through the fax database (step 4) and display
the user’s list of transit faxes from which he can select and assign destination fax numbers (see Figure 3). Once this has taken place, faxes will be transmitted using an Internet fax transport mechanism (steps 5 and 6).
Figure 3. Fax Launch Page
A user can also flexibly form mini-faxes by selecting individual or a set of pages within a fax (i.e. a single fax comprises a number of pages) instead of the usual constrain of sending all the pages. With this facility, a user can fax a stack of pages to the gateway and then select pages
to be sent to different recipients. 4. System Architecture Fax Dispatcher TCP File Transfer Transportation Methods Fax-In Server
Fax Spooler Local
PSTN SMTP Fax Number Resolver Fax Receiver The Internet Fax Machine Fax Machine Incoming Fax Handler Local PSTN Transit Fax Database Fax-Out Server HTTP Server Fax Launch Engine WWW Browser
Fax Machine Fax Machine
Figure 4. System Architecture of the WAX System
Figure 4 shows the system architecture of WAX, which consists of two major gateways: the Fax-In and Fax-Out Gateway. The Fax-In Gateway’s main role is to accept faxes over the PSTN. It would place these faxes in the transit fax database. A HTTP server, within the Fax-In Gateway, communicates with client WWW browsers of users accessing their transit faxes [Fielding et al. 1997]. The HTTP server uses the fax launch engine to access the database and call the fax dispatcher to transmit faxes through the Internet. The fax dispatcher identifies the corresponding Fax-Out Gateway through the fax number resolver component. It coverts fax messages into fax image files and sends the files to the Fax-Out Gateway using an Internet transportation method of either SMTP or TCP file transfer [Postel 1981], depending on availability.
The fax receiver of the Fax-Out Gateway will receive the fax image file, and the fax
spooler will then prepare the faxes to be sent to the destination fax machines through the local
PSTN.
4.1 Fax -In Gateway
4.1.1 Incoming Fax Handler
The incoming fax handler used is Gert Doering’s Mgetty [Doering 1997]. It is essentially a background process that waits for incoming faxes, and manages them accordingly. The handler hides the intricacies of the fax protocols from WAX.
4.1.2 Transit Fax Database
When faxes arrive at WAX, the incoming fax handler places them into the transit fax database. These faxes are stored for a definite time until they are deleted by the system. During this period, users can log into WAX and launch their faxes. The transit fax database is logically divided into individual fax-boxes based on the TIDs of the registered fax machines. When a fax arrives, it is placed into its own fax-box within the database. Faxes from unregistered fax machines are automatically discarded.
4.1.3 Fax Dispatcher
The fax dispatcher acts as a transmission client during the faxing process. It is called by the fax launch engine. Once invoked with a fax message and destination fax number, it will contact the fax number resolver component to determine an appropriate Fax-Out Gateway capable of handling the delivery. The fax dispatcher will then package the faxes into a fax file along with other source and destination information such as destination fax number, destination user's name, sender’s name and email address and fax number. The fax dispatcher also determines a transportation method to deliver the fax file to the Fax-Out Gateway.
4.1.4 Fax Number Resolver
The fax number resolver provides a service to the fax dispatcher to identify a Fax-Out Gateway capable of handling a particular IDD fax number. It returns the gateway address and a local number of the recipient.
In order to resolve incoming phone number requests, the fax number resolver maintains a database. When the fax dispatcher wishes to transfer fax files, it will query the fax number
resolver, which in turn does a database lookup to return the answer. The role of the fax number resolver is to provide the information necessary for the fax dispatcher to carry out the intended
fax transfer. The fax number resolver’s database is "static" in nature and does not change in the course of operation. The database stores information about available Fax-Out Gateways including the type of transportation method that each one uses.
4.1.5 HTTP Server
The HTTP server is a standard web server that provides an information service to HTTP clients (i.e. WWW browsers). The HTTP server is necessary to convey static WWW pages to the user, as well as to provide an interactive mechanism to display and accept dynamic information from users. Most of this is commonly done using HyperText Markup Language (HTML) forms and Common Gateway Interface (CGI) modules.
4.1.6 Fax Launch Engine
Fax launch engine is the main processing engine needed for WAX’s operations. It is implemented using CGI modules. It enables interaction between WWW browsers and the HTTP server. The fax launch engine needs to access the transit database to provide current information about transit faxes to the user. Finally, the engine also has to call the fax
dispatcher to transmit the faxes across the Internet.
4.2 Fax -Out Gateway
The Fax-Out Gateway comprises the following components:
4.2.1 Fax Receiver
The fax receiver is a background process that waits for incoming fax files from the Internet. These could either be faxes packaged within email, or a fax file received through a TCP stream. The fax dispatcher within the Fax-In Gateway should have resolved the Fax-Out Gateway and already determined the format which the fax receiver accepts.
Upon receipt, the file is decompressed and checked for validity. The destination fax number is also checked to determine if it is an authentic local number in the context of the region. Once fully verified, the extracted fax images are converted into a suitable graphics format before faxing out. A well-known third-party graphic file manipulation package, PBMPlus [Poskanzer 1991], was used to provide image conversion between various file formats. PBMPlus includes several fax group 3 (G3) utilities to perform necessary conversions to and from other graphic formats.
4.2.2 Fax Spooler
The fax spooler is a background process that waits for G3 fax images and transmits them out over the PSTN. It consists of two smaller components, namely, the spool dispatcher and the spool daemon. The spool dispatcher accepts incoming files (i.e. from the fax receiver) and places the fax images into a queue. The spool daemon would regularly check this queue for work. If there are files waiting to be transmitted, it removes the oldest fax file and transmits it by sending commands to the fax hardware via the drivers. The Mgetty+Sendfax package [Doering 1997] is used for fax spooling.
5. System Evaluation
The WAX system was successfully developed and implemented on a PC platform running Linux [Volkerding et al. 1997], a variant of Unix. In this section, the WAX system is evaluated and compared with some existing methods and systems. The evaluation is carried out as follows. Firstly, a comparison of the WWW-assisted destination addressing method with other existing methods such as DTMF, BFT, VR and OCR is given. WAX’s system features are then compared with two existing systems [Patel et al. 1994; Yu and Tseng 1997].
5.1 Destination Addressing Methods 5.1.1 System Requirements
Table 1 gives requirements of the additional hardware and special software required for each destination addressing method. Additional hardware refers to extra equipment required such as a computer, or audio input and output devices apart from the standard fax machines and modems. Special software refers to special programs required in order for the sender to use the fax system, or for the gateway to operate.
Table 1. System Requirements for Various Destination Addressing Methods
Sender Fax Machine Fax-In Gateway
Destination Addressing
Methods Hardware Software Hardware Software
DTMF Touch-tone telephone No Audio play-out unit, and DTMF decoder Audio play-out and DTMF handling modules VR No No Audio play-out and voice recording units VR modules OCR No No No Document Image Processing module with an OCR engine BFT BFT-enabled fax-device connected to a computer BFT packaging modules BFT-enabled fax receiving device BFT de-packaging modules WWW Assisted Addressing Internet-connected computer WWW browser No WWW server, CGI modules and
databases
As shown in Table 1, DTMF, VR and BFT methods require additional hardware and software to be installed. This generally makes it more difficult for users, and will also raise the cost of developing the gateway in order to cater for an expanding number of users. The OCR method requires special software in order to perform character recognition. Although using the WWW-assisted method requires a computer with Internet connectivity, it provides enhanced features such as the multi-casting of faxes, faxing to email and the dynamic selection of different pages to be sent to different recipients. In addition, the use of off-the-shelf equipment will increase gateway scaleability and reduce development and operational costs.
5.1.2 Assessment Factors
A number of factors can be used to assess the efficiency and usefulness of the different destination addressing methods. These factors include:
• User base – An addressing method must be designed with the expected set of users in mind. For example, if a system targets the general population, it would be a better idea to remove the necessity for additional software and hardware. On the other hand, a more controlled environment, such as a company, can support supplementary equipment, which can be easily installed for each user to provide enhanced capabilities and more efficient fax transportation.
• Learning – A fax system should be easy and intuitive to use. It would be difficult to implement a system that does not require any learning. However, it should be kept to a minimal to remain user- friend ly. Help given to assist the user, via voice or on-screen prompts would also speed up the process.
• Expandability – The system should be designed intuitively so that users can easily apply their existing operational knowledge to use additional or enhanced services. Examples of additional communication features include fax-to-mail, voice messaging and paging, while enhanced fax services include multi-casting of faxes and automatic fax forwarding.
• Scaleability – Generally, in order to expand a system to support more users, the incoming fax device pool has to grow. At the same time, processing power has to increase to match the upsurge in load. More hardware and software would have to be installed.
• Reliability – A main concern that users have when using an Internet fax system is the reliability of the addressing method. For instance, the dialing of a wrong number using touch-tone telephones is already quite a common occurrence in daily usage. This will inevitably also occur with addressing methods like DTMF. To increase reliability, the system should have a feedback mechanism to allow a user to verify the destination number entered.
5.1.3 Comparison
The above assessment factors have been used to rate each of the methods under comparison. The results of these comparisons are shown in Table 2.
Table 2. Comparison of Various Destination Addressing Methods Destination
Addressing Methods
User Base Learning Expandabilit
y Scaleability Reliability
DTMF Many Easy Difficult Difficult Moderate
VR Many Moderate Difficult Difficult Not good
OCR Moderate Moderate Moderate Moderate Moderate
BFT Few Difficult Easy Moderate Good
WWW Assisted Addressing
Many Easy Easy Easy Good
DTMF keypads have become more and more commonplace in the telecommunications scene, and have rapidly replaced the older rotary-pulse phones. Fax machines are all equipped with these DTMF keypads. In general, users are fairly familiar with interactive DTMF services making learning minimal. However, DTMF is rather hardware intensive on the gateway’s end. The need for pools of DTMF decoders and audio play-out units are expensive, especially if the service targets the masses. In order to scale the system to support more users, all the hardware would have to be replicated. To provide better reliability and reduce input-errors, voice prompts to “read-back” the user’s input can be employed.
The use of Voice Recognition, instead of DTMF, seems like an innovative and novel idea. However, in the long run, its efficiency and reliability fall short in comparison to its DTMF push-button counterpart. VR users have to train the system to recognise the words to be used, together with other speech parameters (e.g. accent, tone and volume) that will generate the
highest recognition accuracy. Moreover, background noise would also significantly affect the precision of the system.
Binary File Transfers cannot be accomplished using conventional stand-alone fax machines thereby reducing the size of the user base. Instead, special software must be executed on a PC with an attached fax modem, thereby forcing users to install and learn the applications in order to send faxes. However, the design of the BFT packaging protocols allows extra information to be included within outgoing BFT messages. This expandable mechanism allows for the incorporation of other features into the system. Additionally, as BFT is software-based, the system can be scaled by the introduction of more processes handling incoming faxes. The digital and discrete nature of BFT packaging also provides a high degree of reliability.
The Optical Character Recognition solution makes the fax system somewhat less accessible to people by requiring the use of “properly” written or typed characters, possibly on pre-formatted forms or in obligatory formats. These conditions limit the user base. A proficient OCR engine coupled with a flexible, or formless, specification format could, to a certain extent, make the system easier to use. As an OCR system can be fully implemented in software, the system can be easily scaled by the inclusion of additional processes without the need for excessive hardware replication. With current OCR technology, recognition accuracy has reached an acceptable level making it a viable destination addressing method. Users can thus expect a good degree of reliability, although the occasional error cannot be ruled out.
As already seen, the need to prepare fax documents prior to sending using OCR, and the need for specialised fax equipment and software for BFT greatly reduces the accessibility of the fax system to the users. The WWW-assisted addressing method eliminates this problem and also reduces server hardware requirements by providing the fax-in facility using plain faxing (i.e. no DTMF or VR interaction is needed). The method’s main interface is the WWW, which can be accessed by a host of popular browsers on virtually any platform. Many enhancements can be easily incorporated into the system using standard WWW pages and CGI scripts. In addition, the use of standard off-the-shelf fax equipment and easily written software modules make the WWW-assisted addressing method economically scaleable to handle a large number of users. Most importantly, the WWW provides a highly reliable front-end to capture input from a user, together with online help in the form of text, graphics and other possible media.
5.2 Comparison with Other Systems
This section compares the system features of WAX with the Multimedia Fax-MIME Gateway [Patel et al. 1994] and the Multimedia Gateway for Phone/Fax and MIME Mail [Yu and Tseng 1997]. The Multimedia Fax-MIME Gateway was developed based on the MIME and BFT formats. The Multimedia Gateway uses the DTMF method to accept receiver information from the sender over the PSTN. Table 3 compares the functionality of these two systems with WAX.
Table 3. Functionality Comparison of the WAX and other systems
Enhanced Feature Fax-MIME Gateway Multimedia
Gateway WAX
Multicast Yes Yes - To
pre-defined groups Yes
Dynamic selection of pages for delivery
No - All pages must be sent
No - All pages must be sent
Yes - Mini- faxes can be formed out of a normal
fax
Transit storage for delayed or multiple deliveries No No Yes Fax-to-fax without intervention Yes No Yes – Using Direct Fax Through Dynamically add
cover notes No No Yes
As mentioned above, the WWW-assisted fax system provides functionality that the other systems cannot. Examples of such features include:
5.2.1 Dynamic Mini-fax Formation
Fax pages A1, A2, A3Destination Fax #1
Destination Fax #2 Destination Fax #3 Fax pages B1, B2, B3 Fax pages C1, C2, C3 Sender Fax Machine
(a) using conventional approach
Destination Fax #1 Destination Fax #2 Destination Fax #3 Fax Gateway Sender Fax Machine
Fax Pages A1, A2, A3, B1, B2, B3, C1, C2, C3
Pages A1, A2, A3
Pages B1, B2, B3 Pages C1, C2, C3
The Internet
(b) using WAX’s mini-faxes
Figure 5. Sending Multiple Faxes to Multiple Recipients
One of the most useful features that WAX offers is its ability to dynamically select pages to form personalised faxes for different recipients. Once a fax message is received into
transit, a user can form mini- faxes using any combination of the encompassing pages. A conventional fax transmission delivers all faxed pages to a single recipient. As shown in Figure 5 (a), if N different faxes have to be sent out, N separate calls have to be made. WAX improves this process by allowing a user to fax his entire stack of documents to the gateway in a single fax transmission. He would then log on to WAX and dynamically form mini- faxes by assigning different destination addresses to different pages. Mini- faxes effectively subsets the original fax into smaller faxes to be distributed dynamically as required. Figure 5 (b) shows that by using WAX, the user needs only carry out a single 9-page fax transmission to the gateway, as opposed to 3 separate 3-page fax transmissions, resulting in the reduction of tedious dialing and phone charges. Taking full advantage of faxes that have been stored in transit, WAX allows a user to repeatedly dispatch faxes.
5.2.2 Cover Note Addition
To supplement the creation of personal mini- faxes, WAX provides the capability to dynamically create cover notes for outgoing faxes. This capability allows mini- faxes to be accurately addressed with attached notes without the need for the sender to explicitly prepare and include his own sheets within transit fax messages.
5.2.3 Direct Fax Through
Fax 651234567 Fax 017926559 Fax Gateway The Internet Fax Gateway Fax Gateway Joe's registered fax
Figure 6. Direct Fax Through
Another feature that WAX supports is Direct Fax Through (DFT). With this, users can set-up virtual connections for the automatic routing of faxes directly to specified destinations. DFT not only saves time, but also provides a quick way to use a conventional fax machine to disseminate information to a group of recipients via fax. For example, if Joe has specified his Direct Fax Through as "651234567 017926559 (i.e. 2 destinations), incoming faxes from his registered fax machine would be automatically transmitted as shown in Figure 6. If DFT has been set, faxes will not be transit stored in Joe's fax-box, as all incoming faxes will be immediately faxed through to the specified destinations. This mode is also useful if a large number of faxes would have to be transmitted to a fixed group of recipients.
5.2.4 Enhanced Reliability
Figure 7. Transit Fax-Image View
WAX offers enhanced reliability in terms of on-screen verification and acknowledgements. Telephone keypads are not suitable for typing in long strings of numbers as users find themselves keying in wrong numbers, losing their concentration and having to redo the sequence and so on. WAX bypasses all these problematic situations by using WWW interface with its online visual forms and capacity for graphics. For example, WAX allows users to verify that he is addressing the correct fax page by providing on-screen reduced-images of the page, as shown in Figure 7.
6. Conclusion
WAX has proven to be extremely useful and economical over conventional faxing and other Internet fax systems. The universality and homogeneity of the WWW adds to the attractiveness of the scheme as well as enhances its global potential as a communications tool. WAX shows considerable potential in providing an integrated faxing environment to support end-to-end fax communications over the Internet. In this paper, we have described the system architecture and design of the WAX system, which consists of two major gateways: the Fax-In and the Fax-Out Gateways. The Fax-In Gateway accepts incoming faxes and prepares them for transmission over the Internet based on user input from the WWW. These fax would traverse through the Internet using either email or TCP pipes. The Fax-Out Gateway receives faxes from the Fax-In Gateway and sends them out over the local PSTN. The WWW-assisted integrated environment allows users to use conventional fax machines to transmit their faxes and employs the web’s friendly interface to facilitate the entry of destination fax numbers as well as a host of other enhanced features.
References
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