Patent Application
20120057192
The present invention relates generally to the electrical, electronic, and computer arts, and more particularly relates to facsimile communications.
Despite efforts to become a paperless society and regardless of the prevalence of email communications, facsimile (or fax) transmission of printed materials (e.g., text, photographs, or the like) remains vital, particularly for business users. One reason for the continued popularity of faxes is that, unlike email attachments or digital signatures, the signature on a fax document is legally binding. Moreover, fax documents retain the format of the original source document and are virtually uneditable.
A traditional analog fax generally involves the transmission of scanned-in printed material (text or images), usually to a telephone number associated with a printer or other output device via a public switched telephone network (PSTN), as specified, for example, in the International Telecommunication Union (ITU) T.30 standard (see, e.g., ITU-T Recommendation T30, Series T: Terminals for Telematic Services, Procedures for Document Facsimile Transmission in the General Switched Telephone Network, September 2005, the disclosure of which is incorporated by reference herein in its entirety for all purposes). The original source document is scanned in by the fax machine, which treats the contents as a single fixed graphic image, converting it to a bitmap. Once in this digital form, the information is transmitted as electrical signals through the telephone system. The receiving fax machine reconverts the coded image and prints a paper copy of the document.
As the transmission of voice over the internet, using voice over internet protocol (VoIP) technology, permeates private and public organizations, such organizations find it desirable to leverage the value and convenience of their single, distributed IP communications network. Since fax transmissions generally utilize the same facilities as voice communications, it is becoming increasingly popular to implement fax transmissions using facsimile over internet protocol (FoIP) as specified, for example, in the ITU T.38 standard (see, e.g., ITU-T Recommendation T38, Series T: Terminals for Telematic Services, Facsimile—Group 3 Protocols, Procedures for Real-time Group 3 Facsimile Communication Over IP Networks, April 2007, the disclosure of which is incorporated by reference herein in its entirety for all purposes).
Conventionally, analog fax engines are used by analog fax machines to send and receive images over a PSTN connection, while T.38-based IP fax engines are used in IP-aware fax machines and FoIP media gateways. Principles of the invention, in illustrative embodiments thereof, advantageously enable fax machine vendors to use a single fax engine operative to transmit/receive fax data (e.g., representative of printed materials—text, images, or the like) using both PSTN and IP network protocols. A simple AT command set is included, according to aspects of the invention, for controlling the operation of the new fax engine.
In accordance with one embodiment of the invention, a facsimile apparatus includes a user interface operative to facilitate communications between the apparatus and at least one user application in operative communication with the apparatus, and a network interface operative to facilitate communications between the apparatus and at least one of a plurality of communications networks coupled to the apparatus. The apparatus further includes a controller connected to the user interface and network interface. The controller is operative in a first mode to communicate with a first one of the communications networks using a first protocol and is operative in at least a second mode to communicate with a second one of the communications networks using a second protocol.
These and other features, objects and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
The following drawings are presented by way of example only and without limitation, wherein like reference numerals indicate corresponding elements throughout the several views, and wherein:
It is to be appreciated that elements in the figures are illustrated for simplicity and clarity. Common but well-understood elements that may be useful or necessary in a commercially feasible embodiment may not be shown in order to facilitate a less hindered view of the illustrated embodiments.
Principles of the present invention will be described herein in the context of illustrative embodiments of a universal facsimile engine adapted to be employed in both a public switch telephone network (PSTN) and an Internet Protocol (IP) network. It is to be appreciated, however, that the invention is not limited to the specific apparatus and methods illustratively shown and described herein. Rather, aspects of the invention are directed broadly to techniques for beneficially integrating features of two or more facsimile protocols. In this manner, aspects of the invention provide a single facsimile engine that can be beneficially used in a variety of applications using multiple protocols and/or data formats.
While illustrative embodiments of the invention will be described herein with reference to ITU-T T.30 and T.38 protocols, it is to be appreciated that the invention is not limited to use with these particular protocols. Rather, principles of the invention may be extended to essentially any facsimile communications protocol, both standard and non-standard. Moreover, it will become apparent to those skilled in the art given the teachings herein that numerous modifications can be made to the embodiments shown that are within the scope of the present invention. That is, no limitations with respect to the specific embodiments described herein are intended or should be inferred.
As is well known by those skilled in the art, particularly in the context of modem communications, an AT command is a command line sequence including a string of characters typically sent from data terminal equipment (DTE) to a modem or other data communication equipment (DCE) while the modem is in a command state. A command line preferably has a prefix, a body, and a terminator portion. Each command line (with the exception of the “A/” command) generally begins with the character sequence “AT” and is terminated by a carriage return. Characters that precede the AT prefix are ignored. The command line interpretation begins upon receipt of the ENTER key character. Characters within the command line are parsed as commands with associated parameter values. The basic commands consist of single ASCII characters, or single characters proceeded by a prefix character (e.g., “&” or “+”), followed by a decimal parameter. It is to be understood that the invention is not limited to use with AT commands or command lines in general.
Analog fax engine 100 may be controlled by one or more user applications 112 via an AT command interface with a well-defined set of AT commands, as specified, for example, in the ITU-T T.31 (Class 1) and ITU-T T.32 (Class 2) standards (see, e.g., ITU-T Recommendation T.31, Terminals for Telematic Services, Asynchronous Facsimile DCE Control—Service Class 1, August 1995; and ITU-T Recommendation T32, Terminals for Telematic Services, Asynchronous Facsimile DCE Control—Service Class 2, August 1995, the disclosures of which are incorporated by reference herein in their entirety for all purposes), or an alternative control application. The user application 112 preferably employs a T.30 protocol 110 (if the system supports a class 1 interface), which may be implemented as part of the user application, for communicating with the analog fax engine 100. Conversely, the T.30 protocol may be implemented externally to the user application, such as by a proxy residing between the user application and the analog fax engine 100. Fax image data, representative of printed materials (e.g., text, photographs, or the like) to be transmitted, are sent through the AT interface to the analog fax engine 100, where they are properly formatted by the modem controller 104 and modulated by the fax data pump 106 for transmission via the PSTN 109.
As previously stated, with the prevalence of data communications over the Internet in general, and VoIP technology specifically, since fax transmissions generally utilize the same facilities as voice communications, it is becoming increasingly popular to implement fax transmissions over the Internet, for instance using FoIP. Two separate protocols enable fax transmissions to be sent effectively over an IP network; namely, the T.30 and T.38 protocols. The T.30 protocol was designed to be implemented over a network (e.g., PSTN) that provides relatively smooth and uninterrupted data flows. Unfortunately, however, the T.30 fax protocol using fax data pump 106 does not tolerate latency, jitter, and packet-loss, among other characteristics that are commonly encountered in an IP network. Moreover, compression often implemented by VoIP networks works well for speech (based on the limited frequency response of the human ear and our ability to “fill in the gaps” when certain sounds are missing from spoken words); however, distortion caused by compression and packetization can be enough to cause a T.30 transmission to fail at worst or to produce one or more erroneous image lines at best.
The T.38 fax protocol addresses at least a portion of the problems associated with sending and receiving faxes in real-time over a packet network. T.38 supports the transmission of fax data across an IP network in real time, much like the original Group 3 (G3) fax standards did for the traditional PSTN. In this manner, T.38 preserves the traditional fax environment and yet allows faxes to be successfully sent and received by dynamically adjusting the transmitted fax signal to compensate for jitter, latency, and packet loss, which are common in the IP network. Without T.38, fax devices, which are sensitive to timing, would otherwise experience difficulty reliably sending and receiving faxes over an IP network.
While not explicitly shown, the IP-aware fax engine 200 may further include a modem controller and fax data pump. In the IP network, an IP-based fax session may or may not require a modem controller and data pump, depending on the application employed. The IP-aware fax engine 200 further comprises an IP fax packet buffer 206, or alternative buffer. Buffer 206 is operative to provide an interface between the IP-aware fax engine 200 and an IP network (IPN) 208. Buffer 206 is preferably operative to receive data packets from the T.38 protocol stack 204 and reformat them for transmission over the IP network 208. Likewise, packets received from the IP network 208 by the buffer 206 are preferably reformatted by the buffer for use by the T.38 protocol stack 204.
IP-aware fax engine 200 may be controlled by one or more user applications 210 via an IP signaling protocol unit 212, or an alternative interface/control block. IP signaling protocol unit 212 preferably interfaces with the IP-aware fax engine 200, and sets up fax calls using a known communications protocol, such as, for example, Session Initiation Protocol (SIP), ITU-T H.323 (see, e.g., ITU-T Recommendation H323, Series H: Audiovisual and Multimedia Systems, Infrastructure of audiovisual services—Systems and terminal equipment for audiovisual services, Packet-based multimedia communications systems, December 2009, the disclosure of which is incorporated by reference herein in its entirety for all purposes), or an alternative control and/or signaling protocol. As previously stated, it is to be understood that the invention is not limited to use with any specific communications protocol(s).
The T.30 fax protocol stack 202 is operative to receive fax image data and/or control signals from, or transmit fax image data and/or controls signal to, user application 210. T.30 fax protocol stack 202 is preferably further operative to specify the procedures that a sending and receiving terminal use to set up a fax call, determine the image size, encoding, and transfer speed, the demarcation between pages, and/or the termination of the call, among other functions, according to the T.30 standard. The T.38 protocol stack 204 is operative to “fool” the terminal into thinking that it's communicating directly with another T.30 terminal. T.38 protocol stack 204, in conjunction with buffer 206, will also preferably correct for network delays with so-called spoofing techniques, and missing or delayed packets with fax-aware buffer-management techniques (e.g., store-and-forward processing).
Fax engine 300, like fax engine 200 shown in
Additionally, fax engine 300, like the analog fax engine 100 shown in
While a dedicated analog fax engine for providing fax transmission over a standard PSTN is known, as is a dedicated IP-aware fax engine for providing fax transmission over an IP network, embodiments of the present invention beneficially support multiple fax protocols (e.g., implementing functionalities of an analog fax engine and an IP-aware fax engine) integrated into a single fax engine. By way of example only,
With reference to
The T.30 protocol 406 is preferably operative to control fax frames, image data, etc., under control of the user application 404. An advantage of this arrangement is that the user can control their own existing T.30 stack through the same standard AT command interface to control both analog fax and IP-based (e.g., T.38) fax. More particularly, the same user application as employed with the analog fax engine 100 shown in
For communication with a traditional PSTN, universal fax engine 400 comprises an analog stack 408 including a modem class 1 data communication equipment (DCE) interface 410, a modem controller 412 coupled to the DCE interface, and a modem data pump 414 coupled to the modem controller. The modem data pump 414 is operatively coupled to a PSTN sample buffer 416. PSTN sample buffer 416, which serves as an interface to an analog PSTN, is operative to send and receive pulse-code modulation (PCM) samples to and from, respectively, the PSTN.
For communication with an IP network, universal fax engine 400 comprises an IP-aware stack 418 including a T.38 protocol class 1 data terminal equipment (DTE) interface 420, a T.38 protocol engine 422 coupled to the T.38 class 1 DTE interface, and an IP signaling protocol (ISP) module 424 in communication with the T.38 protocol engine and the T.38 class 1 DTE interface. The T.38 protocol engine 422 is operatively coupled to an IP fax packet buffer 426. IP fax packet buffer 426, which serves as an interface to an IP network, is operative to send and receive T.38 IP fax packets to and from, respectively, the IP network. This interface can be software based; that is, the physical IP interface (e.g., IP stocks) does not have to reside on the same chip as the T.38 stack (e.g., comprising T.38 class 1 DTE interface 420, T.38 protocol engine 422, and ISP module 424). The universal fax engine 400 can send/receive the IP fax packets to/from, respectively, either user application 404 or other hardware where an actual IP connection exists.
In the exemplary embodiment shown in
Universal fax engine 400 further includes a class 1 fax engine controller 428 coupled between the class 1 AT command parser 402 and the analog stack 408 and the IP-aware stack 418. Fax engine controller 428 is operative to control the mode of operation and/or state of the universal fax engine 400. Specifically, fax engine controller 428 is coupled to AT command parser 402, modem class 1 DCE interface 410 and T.38 class 1 DTE interface 420. There are at least three modes of operation for universal fax engine 400; namely, a first mode, which may be an analog fax modem mode, a second mode, which may be an IP-aware fax mode, and a third mode, which may be a FoIP gateway/ATA mode. Each of these illustrative modes of operation of universal fax engine 400 will be described in further detail below in conjunction with
In a receive direction, IP fax data packets from the IP network are decoded into regular T.30 messages, via the IP-aware stack 418, and sent to the user application 404 via the class 1 interface 402. In the transmit direction, T.30 data from user application 404 is encoded into proper T.38 IP fax packets, via IP-aware stack 418, and forwarded to the IP network. This mode is used by terminating T.38 devices, such as, for example, an IP-aware fax modem/machine. An IP network signaling protocol (e.g., SIP, H.323, etc.) can be used to setup a call, but such protocol need not reside in the fax engine 400. Rather, a user can invoke the signaling protocol elsewhere and simply pass the negotiated information to the fax engine.
With reference now to
More particularly, in this mode of operation the fax engine functions as a media gateway or analog telephone adaptor. In a first direction (e.g., PSTN-to-IP network transfer), an analog signal received from the PSTN, via PSTN sample buffer 416, is demodulated and decoded by the analog stack 408 into T.30 data (or data in an alternate communications protocol). This decoded data is then sent, via the fax engine controller 428, to the IP-aware stack 418, where it is encoded into T.38 IP fax packets (or an alternate protocol) and sent out to the IP network. In a second direction (e.g., IP network-to-PSTN transfer), IP fax packets received from the IP network, via IP fax packet buffer 426, are decoded by the IP-aware stack 418 into T.30 messages (T.30 control frame and image data). The T.30 messages are then sent, via the fax engine controller 428, to the analog stack 408 where they are coded and modulated for transmission via the PSTN. An IP network signaling protocol (e.g., SIP, H.323, etc.) may be used to establish a FoIP call, but such protocol need not reside in the fax engine itself. A user can invoke the signaling protocol elsewhere and simply pass the negotiated information to the fax engine 400.
Modes of operation of the universal fax engine 400, or at least a subset thereof, are preferably controlled by way of an AT command interface, or alternative control/interface methodology. By way of illustration only and without loss of generality, embodiments of the invention provide an AT command set, AT+fclass=nclass, defining a new mode class, IP fax class. This class is assigned a number (e.g., 9) which is not currently used by any other mode of the traditional analog modem command set. For example, operational modes of the universal fax engine may be defined as follows:
AT+fclass=9.1, IP-aware fax mode with class 1 (T.31) interface;
AT+fclass=9.2, IP-aware fax mode with class 2 (T.32) interface;
AT+fclass=9.3, FoIP gateway/ATA mode;
AT+fclass=9.4, IP-aware data modem mode;
AT+fclass=9.5, MoIP gateway/ATA mode.
The existing AT+fclass=commands preferably still function as in a traditional analog fax/data modem. For example, the following commands are operative with the universal fax engine:
AT+fclass=0, traditional analog data modem mode;
AT+fclass=1.0, traditional analog fax modem mode with class 1 interface;
AT+fclass=2.0, traditional analog fax modem mode with class 2 interface.
The above exemplary command definitions are presented by way of illustration only. It is to be understood, however, that the invention is not limited to the specific command definitions shown and described herein. Rather, other and/or additional command definitions may be utilized, as will become apparent to those skilled in the art given the teachings herein.
Methodologies of embodiments of the present invention may be particularly well-suited for implementation in an electronic device or alternative system, such as, for example, a network router/switch device. By way of illustration only,
It is to be appreciated that the term “processor” as used herein is intended to include any processing device, such as, for example, one that includes a central processing unit (CPU) and/or other processing circuitry (e.g., network processor, DSP, microprocessor, etc.). Additionally, it is to be understood that the term “processor” may refer to more than one processing device, and that various elements associated with a processing device may be shared by other processing devices. The term “memory” as used herein is intended to include memory and other computer-readable media associated with a processor or CPU, such as, for example, random access memory (RAM), read only memory (ROM), fixed storage media (e.g., a hard drive), removable storage media (e.g., a diskette), flash memory, etc. Furthermore, the term “I/O circuitry” as used herein is intended to include, for example, one or more input devices (e.g., keyboard, mouse, etc.) for entering data to the processor, one or more output devices (e.g., printer, monitor, etc.) for presenting the results associated with the processor, and/or interface circuitry for operatively coupling the input or output device(s) to the processor.
Accordingly, an application program, or software components thereof, including instructions or code for performing the methodologies of the invention, as described herein, may be stored in one or more of the associated storage media (e.g., ROM, fixed or removable storage) and, when ready to be utilized, loaded in whole or in part (e.g., into RAM) and executed by the processor 802. In any case, it is to be appreciated that at least a portion of the components shown in
At least a portion of the techniques of the present invention may be implemented in one or more integrated circuits. In forming integrated circuits, die are typically fabricated in a repeated pattern on a surface of a semiconductor wafer. Each of the die includes a memory described herein, and may include other structures or circuits. Individual die are cut or diced from the wafer, then packaged as integrated circuits. One skilled in the art would know how to dice wafers and package die to produce integrated circuits. Integrated circuits so manufactured are considered part of this invention.
An IC in accordance with embodiments of the present invention can be employed in any application and/or electronic system which is adapted for providing fax communications (e.g., fax modem/machine). Suitable systems for implementing embodiments of the invention may include, but are not limited to, personal computers, portable communications devices (e.g., cell phones), fax devices, etc. Systems incorporating such integrated circuits are considered part of this invention. Given the teachings of the invention provided herein, one of ordinary skill in the art will be able to contemplate other implementations and applications of the techniques of the invention.
Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be made therein by one skilled in the art without departing from the scope of the appended claims.
