WO1999030477A1

WO1999030477A1 - System and method for dual-mode speech and data interface with a selection signal

Info

Publication number: WO1999030477A1
Application number: PCT/US1998/025976
Authority: WO
Inventors: Jeffrey Michael Lucak
Original assignee: Ericsson Inc.
Priority date: 1997-12-10
Filing date: 1998-12-08
Publication date: 1999-06-17
Also published as: WO1999030477A8; AU1715999A

Abstract

An apparatus, system, and method are presented for permitting a user to select whether the user's subscriber line will transmit in either the data or audio mode. A dual-mode apparatus is possible because of a select of which either connects the subscriber line to audio facilities or data facilities. The subscriber line belonging to the recipient is automatically connected to the data or audio facilities, based on the mode selected by the user.

Description

SYSTEM AND METHOD FOR DUAL-MODE SPEECH AND DATA INTERFACE WITH A SELECTION SIGNAL

BACKGROUND OF THE PRESENT INVENTION Field of the Invention

The present invention relates generally to signal transmission in telecommunication systems and methods, and specifically to a dual mode speech and data interface with an activation code.

Background and Objects of the Invention In recent years, the amount of data being communicated across telecommunications networks has increased significantly. With the increasing number of personal computers and FAX machines, and the rising popularity of the Internet, the amount of data transmitted over telecommunications networks is expected to increase even more. The amount of data being transmitted in a typical data transmission is also increasing. Whereas, most previous data transmissions were textually-based, data transmissions increasingly involve audio, graphical, and even high resolution video data. While one typical page of text may contain about 3K bytes of informational content, a single second of sound typically requires 8K bytes, a picture-quality graphic requires around 15K bytes, and a single second of movie-quality video requires as much as 500K bytes.

As is well understood, high-speed data transmissions are necessary to make practical use of data transfers. Slow data transfers result in unacceptable transmission delays, make interactions impractical, and lead to customer dissatisfaction. A medium for data transmission that is popular today is a channel in a telecommunications network. However, because telecommunications channels were originally designed for audio transmissions, data must be adapted for audio transmission.

Referring now to FIGURE 1, a portion of a telecommunications system 100 is shown with two end offices 110a, 110b, each connected to a plurality of subscriber lines 120a, 120b, and interconnected by a trunk 140. In order to transmit data from a device 150a to another device 150b, §_g., two computers, the devices 150a, 150b are connected to the subscriber lines 120a, 120b, respectively. However, because the subscriber lines were designed for audio transmission, the end office 110a expects an incoming signal with a frequency in the audible range

(an audio signal). Because the end office 110a expects an audio signal, the end office 110a only examines the portion of the signal which is in the audible frequency range (100 Hz to 5 KHz) when digitizing the signal for transmission across the trunk 140. Likewise, when the digitized signal is received at the receiving end office 110b from the trunk 140, the reconstruction performed by the receiving end office 110b only reconstructs audio signals and cannot reconstruct signals at higher frequency ranges. The audio signal is then transmitted across the subscriber lines 120b to the destination device 150b.

Accordingly, the data from the sending device 150a must first be converted to an audio signal which is expected by the end office 110a. The conversion is usually performed by what is known by those skilled in the art as a modulator/demodulator or modem. Likewise, the audio data forwarded by the end office 110a across trunk 140 to the end office 110b must then be converted to a data signal compatible with the receiving device 150b. This conversion is also generally performed by a modem.

This audio/data conversion imposes another limitation on the speed of the data transmission, which can only be as fast as the modem can convert. Currently, some commercially available modems are capable of converting at speeds up to 56 Kb/s. However, because the vast majority of audible sounds fall within the 300 Hz to 3 KHz range, the digitization of the signal by the end office 110a has a tendency to be imperfect at the edges of the audible range (100 - 300Hz, and 3 - 5 KHz). Therefore, the actual speeds at which the data is transferred between two devices 150a, 150b, is often substantially lower because the transmission facilities used for the connection are optimized to audio signals. Another proposal for high-speed data transmission is the Integrated Services

Digital Network (ISDN). An ISDN subscriber line (such as 120a) is recognized by an end office (such as 110a) to carry a data signal. The digitization process is not limited to the audio range as in an ordinary voice call. Also, the end office 110a utilizes special trunks 140 which can ensure bit integrity at high data transmission rates. While the use of an ISDN line eliminates the aforementioned conversion limitation, the ISDN protocol is generally very complex. Furthermore, the more expensive ISDN lines are not practical for a subscriber who only occasionally transfers data.

It is, therefore, an object of the present invention to transmit data across a telecommunications network without having to convert the data to an audio signal. It is a further object of the present invention to utilize a channel which is also usable for ordinary speech transmission.

SUMMARY OF THE INVENTION

The present invention is directed to a system, method and apparatus for transmitting data across a telecommunications network by selecting the mode of transmission, when transmitting in the data mode, connecting the subscriber line to a data communications device, and when transmitting in the audio mode, connecting the subscriber line to an audio communications device. The present invention is also directed to an end office having a subscriber line and an interface with a data and an audio communications device. The present invention is also directed to a device for transmitting data with an interface which is able to transmit the data across a subscriber line which receives power from the end office. The present invention is also directed to a system for transmitting data across a telecommunications system which includes a control panel for controlling the mode of transmission, and a selector for connecting the subscriber line either to a data communications device or an audio communications device.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed inventions will be described with reference to the accompanying drawings, which illustrate sample embodiments of the invention and which are incorporated in the specification hereof by reference, wherein: FIGURE 1 is a diagram of a portion of a telecommunications system;

FIGURE 2 is a block diagram of an end office embodying the present invention;

FIGURE 3 is a diagram illustrating end offices in a telephone network; and FIGURE 4 is a block diagram illustrating a pair of end offices embodying the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS The numerous innovative teachings of the present application will be described with particular reference to the presently preferred exemplary embodiments. However, it should be understood that these embodiments provide only a few examples of the many advantageous uses of the innovative teachings herein. It should be understood that statements made in the specification of the present application do not necessarily delimit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. •

Referring now to FIGURE 2, a block diagram of an end office 200 is illustrated. The end office 200 is connected to a subscriber line 220 which is connected to a subscriber device 210. The subscriber device 210 can be, but is not limited to, a FAX machine, a modem, or any other data communications device. As discussed, when the subscriber device 210 transmits data, the output of the subscriber device 210 can be connected directly to the subscriber line 220 with a digital modem not restricted to encoding the data into an audio signal. With further reference to FIGURE 2, the end office 200 includes a Line-Interface Card (LIC)

230 which is connected to a call processing module 240.

The LIC 230 interfaces the subscriber line 220 with the end office 200 and communicates parameters regarding the subscriber line 220 to the call processing module 240. Among the parameters communicated include Dual-Tone Multi- Frequency (DTMF) signals. For example, if a user (not shown) presses one of the numeric keys on a telephone 210, a DTMF is generated and transmitted across the subscriber line 220 to the LIC 230. The LIC 230 decodes the DTMF and indicates to the call processing module 240, that a particular key has been pressed. Those skilled in the art will recognize that there are a number of devices 210 which can automatically generate DTMF signals corresponding to directory numbers without requiring a user to press a key.

The LIC 230 also includes an analog/digital pulse code modulator 231 (A/D PCM), a data modem 232, and a selector 233. The A/D PCM 211 digitizes and reconstructs audio signals transmitted on the subscriber line 220. The data modem 232 is used when data signals are received on the subscriber line 220 (such as 140 in FIGURE 1 ). Unlike the A/D PCM, the data modem 232 expects to receive a data signal instead of an audio signal. The data modem 232 also employs error correction coding to facilitate the transmission. Consequently, the digitization and reconstruction performed by the data modem 232 is optimized for integrity at frequencies beyond the audio range. The data modem 232 can be implemented by, for example, what is known in the art as a Digital Subscriber Loop (DSL). The selector 233 connects the subscriber line 220 either to the A D PCM 231 or the data modem 232, depending upon the mode of transmission.

The selector 233 preferably connects the subscriber line to the A/D PCM 231 by default and is controlled by the call processing module 240. The selector 233 can be toggled by the user by setting the subscriber line 220 off-hook and dialing an activation code similar to a code for a caller feature such as call forwarding. Upon dialing the activation code, the LIC 230 decodes the DTMF signals and forwards the dialed numbers to the call processing module 240 which then sends a control signal to the selector 233, causing the selector 233 to connect the subscriber line 220 to the data modem 232. Whenever the user goes on-hook, the LIC 230 informs the call processing module 240, which sends a control signal causing the selector 233 to connect the subscriber line 220 to the A/D PCM 231, the default position.

Referring now to FIGURE 3 of the drawings, several end offices (EOs) 300 are illustrated in a telephone network 390. The EOs 300 also provide an Integrated

Services Data Network (ISDN) User Part(ISUP) protocol for Signal Transfer Points (STPs) 310, as is understood in the art.

Each STP 310 serves as a router, and switches messages received from a particular EO 300 through the network 390 to their appropriate destinations (another EO 300). It should be understood that the STPs 310 preferably receive such messages in packet form the EO 300. These packets are either related to call connections or database queries. If the packet is a request to connect a call, the message is forwarded to a destination end office (another EO 300), where the call will be terminated.

When the user is transmitting data across a subscriber line (such as 220 in FIGURE 2), the EO 300 serving the user will indicate that the call connection will be transmitting data in the packet of information the EO 300 sends to the STP 310, which then forwards the packet of information to the destination end office (another EO 300).

Referring now to FIGURE 4, an originating end office 420 and a destination end office 440 connected by a trunk connection 430 are illustrated. When setting up the call connection, the originating end office 420 selects a particular trunk 430 to carry the call to the destination end office 440 according to whether the call contains data or audio signals. If the call is carrying audio signals, the end office 420 uses an ordinary trunk 430 which may not maintain bit integrity of the digitized audio signals. On the other hand, if the call is carrying data signals, the originating end office 420 selects a trunk 430 that can assure bit integrity for digital data signals. For example, the originating end office 420 could use, but is not limited to, the clear channel trunks used in ISDN communication.

The destination end office 440 includes a call processing module 441 and an LIC 442. The LIC 442 contains an A/D PCM 449, a data modem 443, and a selector 444, as described in connection with FIGURE 2. The selector 444 connects a subscriber line 445 to the data modem 443 when data is transmitted and connects the subscriber line 445 to the A/D PCM 449 when audio data is transmitted. By default, the selector 444 connects the subscriber line 445 to the A/D PCM 449 for transmissions to a destination device 446.

At the destination end office 440, the call processing module 441 examines the packet of information forwarded by the STP 310 (of FIGURE 3). If the packet of information indicates that data is being transmitted, the call processing module 441 issues a control signal to toggle the selector 444 accordingly, connecting the subscriber line 445 to the data modem 443. The destination end office 440 issues an alert to the destination device 446 indicating an incoming call. For example, a distinctive ringing rhythm could be used if the call is carrying data signals and an ordinary ringing rhythm could be used if the call is carrying audio signals.

For the duration of the call, the data is transmitted across the trunk 430 to the destination end office 440, and then to the user (not shown) at the destination device 446 across the subscriber line 445. At the termination of the call, the call processing module 441 issues a control signal, toggling the selector 444 back to the A/D PCM 449.

Although the invention has been described with a certain degree of particularity, it should be recognized that elements thereof may be altered by persons skilled in the art without departing from the spirit and scope of the invention. For example, while a data transmission to a destination end office with a dual-mode line interface card has been illustrated, in another embodiment, the destination end office could be connected to the destination device by what is known as an ISDN line. In such an embodiment, the line interface card at the destination end office would not include an A/D PCM and a selector. Therefore, the invention is limited only by the following claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A method for transmitting communication signals from a first device to a second device, said method comprising the steps of: receiving, at a first end office, said communication signals from said first device; selecting, within said first end office, a communication mode for transmitting said communications signals to said second device, a data communication mode being selected if said communication signals are data and an audio communication mode being selected if said communication signals are audio; connecting said first device to said second device pursuant to said communication mode selection; and transmitting said communication signals from said first device to said second device pursuant to said communication mode selection.

2. The method of claim 1, wherein said selecting step further comprises: transmitting a communication mode selection signal from said first device, across a first subscriber line to said first end office.

3. The method of claim 2, wherein said selection signal further comprises: a plurality of Dual-Tone Multi-Frequency signals.

4. The method of claim 1, wherein said selecting step further comprises: connecting a first subscriber line to a data communications means within said first end office if said communication signals are data; and connecting said first subscriber line to an audio communications means within said first end office if said communication signals are audio.

5. The method of claim 1 , wherein said transmitting step further comprises: transmitting said communication signals from said first end office to a destination end office, said destination end office being connected to said second device; and transmitting said communication signals from said destination end office to said second device.

6. The method of claim 1, wherein said connecting step further comprises the steps of: transmitting a routing signal from said first end office to a second end office, said routing signal including a communication mode indicator; connecting a second subscriber line from said second device to a data communications means within said second end office if said communication mode indicator indicates a data mode transmission; and connecting said second subscriber line from said second device to an audio communications means within said second end office if said communication mode indicator indicates an audio mode transmission.

7. The method of claim 6, wherein said routing signal transmitted to said second end office is within an Integrated Services Digital Network User Part packet.

8. The method of claim 4, wherein said data communications means comprises a Digital Subscriber Loop.

9. The method of claim 5, wherein said destination end office issues an alert signal to said second device, said alert signal indicating said communication mode selection.

10. The method of claim 9, wherein said second device, receiving said alert signal, generates a first ringing signal if said communication signals are audio, and generates a second ringing signal if said communication signals are data.

11. An end office for facilitating the transmission of communication signals from a first device to a second device, said end office comprising: audio transmission means for transmitting said communication signals in audio through said end office from said first device to said second device pursuant to an audio communication protocol; data transmission means for transmitting said communication signals through said end office from said first device to said second device pursuant to a data communication protocol; and selection means for selecting between said data and audio transmission means for transmitting said communication signals, said selection means selecting said data transmission means if said communication signals are data and said audio transmission means if said communication signals are audio.

12. The end office of claim 11 , wherein said data transmission is for error correction coding.

13. The end office of claim 11 , further comprising: a subscriber line connecting said end office to said first device; and wherein said selection means further comprises a selector, said selector connected to said subscriber line, said data transmissions means, and said audio transmissions means.

14. The end office of claim 13 further comprising: a call processor for controlling said selection means.

15. The end office of claim 14, wherein said call processor further comprises: a controller for controlling said selection means responsive to said selection signal received from said subscriber line.

16. The end office of claim 15, wherein said selection signal further comprises a plurality of Dual-Tone Multi-Frequency signals.

17. The end office of claim 11 , wherein said data communications means comprises a Digital Subscriber Loop.

18. The end office of claim 11 , further comprising: a subscriber line, said subscriber line connecting said second device to said end office; and an alerting means for issuing an alert signal to said second device, said alert signal indicating if said communication signals are data or audio.

19. A telecommunications system for transmitting communication signals, said telecommunications system comprising: a source device for transmitting said communication signals; a destination device for receiving said communication signals; and a first end office, connected between said source and destination devices, said first end office comprising: a first audio transmission means for transmitting said communication signals from said source device through said first end office, to said destination device pursuant to an audio communication mode; a first data transmission means for transmitting said communication signals from said source device, through said first end office, to said destination device pursuant to a data communication mode; and selection means for selecting between said first data and first audio transmission means for transmitting said communication signals, said selection means selecting said first data transmission means if said communication signals are data and said first audio transmission means if said communication signals are audio.

20. The system of claim 19, wherein said source and destination devices are each selected from a group consisting of facsimiles, computers, modems, mobile telephones, and wireline telephones.

21. The system of claim 19, wherein said system further comprises: a second end office, said second end office connected between said first end office and said second device.

22. The system of claim 19, further comprising: a transmitter within said first end office for transmitting a routing signal to a second end office, said second end office being disposed between said first end office and said destination device, said routing signal including a communication mode indicator, said second end office comprising: a second data transmission means for transmitting said communication signals through said second end office to said destination device pursuant to said data communication mode; a second audio transmission means for transmitting said communication signals through said second end office to said destination device pursuant to said audio communication mode; and selection means for connecting a subscriber line from said destination device to said second data transmission means if said communication mode indicator indicates a data mode transmission indicator, and for connecting said subscriber line to said second audio transmission means if said communication mode indicator indicates an audio mode transmission.

23. The system of claim 22, wherein said second end office comprises alerting means for issuing an alerting signal to said second device, said alerting signal indicating said communications mode.

24. The system of claim 23, wherein said second device further comprises a ring generator, said ring generator generating a first ringing signal if said communication mode is audio, and a second ringing signal if communication mode is data.

25. The system of claim 22, wherein said routing signal transmitted to said second end office is an Integrated Services Digital Network User Part packet.

26. The system of claim 19, wherein said first data transmission means is for error correction coding.

27. The system of claim 19, wherein said first data transmission means is a Digital Subscriber Loop.

28. A line interface card for forwarding communication signals from a first device to a second device, said line interface card comprising: transceiving means for receiving said communication signals from said first device and for transmitting said communication signals to said second device; an audio communication means for transmitting said communication signals pursuant to an audio communication mode, said audio communications means; a data communication means for transmitting said communication signals pursuant to a data communication mode; and selection means, said selection means connected to said incoming subscriber line, said audio communication means, and said data communication means, said selection means connecting said incoming subscriber line to said data communications means when the communication mode is data, and said selection means connecting said incoming subscriber line to said audio communications means when the communication mode is audio.

29. The line interface card of claim 28, wherein the communication mode is controlled by a selection signal from said first device across incoming subscriber line.

30. The line interface card of claim 29, wherein said selection signal comprises a plurality of dual-tone multi-frequency signals.

31. The line interface card of claim 29, wherein said selection signal is a user-defined selection signal.

32. The line interface car of claim 29, wherein said data communications means is for error correction coding.