Telecommunication system for automatic switching between voice and data communications

We claim:

1. A telecommunication system for providing voice and data communications between at least two stations over a telephone line that can be dynamically switched between a voice mode and any of a plurality of data modes, each of said stations comprising:

a telephone for voice communications;

switching means for selectively connecting said telephone to said telephone line in said voice mode and disconnecting said telephone from said telephone line in said data modes;

a modem for selectively providing data communications over said telephone line in any of a plurality of data modes;

means for transmitting a start signal over said telephone line to request that remote stations switch to one of said data modes prior to transmission of data by said modem, said start signal including a mode signal indicating one of said data modes;

means for detecting a start signal, including said mode signal, transmitted over said telephone line by a remote station; and

a controller for monitoring said start signal detector and controlling said switching means and said modem to automatically switch from voice mode to a selected data mode when data is being received or transmitted.

2. The telecommunication system of claim 1, wherein said means for transmitting said start signal comprise a plurality of tone generators having preselected frequencies.

3. The telecommunication system of claim 1, wherein said means for detecting said start signal comprise a plurality of tone detectors for detecting tones at preselected frequencies.

4. The telecommunication system of claim 1, wherein said modem is capable of communicating data at any of a plurality of preselected data transmission rates and wherein said start signal comprises a signal indicating one of said data transmission rates.

5. The telecommunication system of claim 1, wherein said start signal comprises at least one tone having preselected frequencies followed by a sequence of HDLC flags.

6. The telecommunication system of claim 1, wherein said mode signal comprises at least one tone having preselected frequencies.

7. The telecommunication system of claim 1, wherein said mode signal comprises data modulated using the CCITT V.21 protocol indicating one of said data modes.

8. The telecommunications system of claim 1, wherein one of said data modes is the VoiceView protocol.

9. The telecommunication system of claim 1, wherein one of said data modes is a facsimile data mode consistent with the CCITT T.30 protocol.

10. The telecommunication system of claim 1, wherein one of said data modes is a modem data mode consistent with the CCITT V.22bis protocol.

11. The telecommunication system of claim 1, wherein each station further comprises means for exchanging information on the data modes supported by each station.

12. The telecommunication system of claim 11, wherein a first station transmits a query over said telephone line to a second station, and said second station responds to said query by transmitting information indicating the data modes that it supports.

13. A telecommunication system for providing voice and data communications between at least two stations over a telephone line that can be dynamically switched between a voice mode and any of a plurality of data modes, each of said stations comprising:

a telephone for voice communications;

a modem for selectively providing data communications over said telephone line in any of a plurality of data modes, said modem having a receive port coupled to said telephone line and a transmit port;

switching means for selectively connecting said telephone to said telephone line in said voice mode and disconnecting said telephone from said telephone line in said data modes, and for selectively connecting said transmit port of said modem to said telephone line in said data modes and disconnecting said transmit port of said modem from said telephone line in said voice mode;

means for transmitting a start signal over said telephone line to request that remote stations switch to one of said data modes prior to transmission of data by said modem, said start signal including:

(a) at least one start tone having preselected frequencies; and

(b) a mode signal indicating one of said data modes;

means for detecting a start signal, including said start tone and said mode signal, transmitted over said telephone line by a remote station; and

a controller for monitoring said start signal detector and controlling said switching means and said modem to automatically switch from voice mode to a selected data mode when data is being received or transmitted;

a processor for providing data to be transmitted by said modem to remote stations and for receiving data from remote stations via said modem; and

a display for displaying data from said processor.

14. The telecommunication system of claim 13, wherein said start signal comprises the following sequence:

a period of silence;

a stad tone having a preselected frequency;

a plurality of HDLC flags; and

a mode signal indicating one of said data modes.

15. The telecommunication system of claim 13, wherein said mode signal comprises at least one tone having preselected frequencies.

16. The telecommunication system of claim 13, wherein said mode signal comprises data modulated using the CCITT V.21 protocol indicating one of said data modes.

17. The telecommunication system of claim 13, wherein said modem is capable of communicating data at any of a plurality of preselected data transmission rates and wherein said start signal comprises a signal indicating one of said data transmission rates.

18. The telecommunication system of claim 13, wherein each station further comprises means for exchanging information on the data modes supported by each station.

19. The telecommunication system of claim 18, wherein a first station transmits a query over said telephone line to a second station, and said second station responds to said query by transmitting information indicating the data modes that it supports.

20. A telecommunication system for providing voice and data communications between at least two stations over a telephone line that can be dynamically switched between a voice mode and any of a plurality of data modes, each of said stations comprising:

data circuit-terminating equipment (DCE) having:

(a) a telephone for voice communications;

(b) a modem for selectively providing data communications over said telephone line in any of a plurality of data modes, said modem having a receive port coupled to said telephone line and a transmit port;

(c) switching means for selectively connecting said telephone to said telephone line in said voice mode and disconnecting said telephone from said telephone line in said data modes, and for selectively connecting said transmit port of said modem to said telephone line in said data modes and disconnecting said transmit port of said modem from said telephone line in said voice mode;

(d) means for transmitting a start signal over said telephone line to request that remote stations switch to one of said data modes prior to transmission of data by said modem, said start signal including:

(1) at least one start tone having preselected frequencies; and

(2) a mode signal indicating one of said data modes;

(e) means for detecting a start signal, including said start tone and said mode signal, transmitted over said telephone line by a remote station; and

(f) a DCE controller for monitoring said start signal detector means and controlling said switching means and said modem to automatically switch from voice mode to a selected data mode when data is being received or transmitted; and

data terminal equipment (DTE) controlling operation of said DCE having:

(a) a processor for and controlling said DCE controller, for providing data to be transmitted by said modem to remote stations and for receiving data from remote stations via said modem; and

(b) a display for displaying data from said processor.

21. The telecommunication system of claim 20, wherein said start signal comprises the following sequence:

a period of silence;

a start tone having a preselected frequency;

a plurality of HDLC flags; and

a mode signal indicating one of said data modes.

22. The telecommunication system of claim 20, wherein said mode signal comprises at least one tone having preselected frequencies.

23. The telecommunication system of claim 20, wherein said mode signal comprises data modulated using the CCITT V.21 protocol indicating one of said data modes.

24. The telecommunication system of claim 20, wherein said modem is capable of communicating data at any of a plurality of preselected data transmission rates and wherein said start signal comprises a signal indicating one of said data transmission rates.

25. The telecommunication system of claim 20, wherein each station further comprises means for exchanging information on the data modes supported by each station.

26. The telecommunication system of claim 25, wherein a first station transmits a query over said telephone line to a second station, and said second station responds to said query by transmitting information indicating the data modes that it supports.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of telephony. More specifically, the present invention discloses a telecommunication system that provides automatic switching between a voice mode and a variety of data modes.

2. Statement of the Problem

The present invention is intended to address the problem of communicating both voice and data by telephone over a single conventional telephone line. It is often desirable to be able to transmit data over a single telephone line interspersed with verbal discussions between the parties. This data can be in the form of visual images relevant to the conversation. For example, a travel agent might wish to show a telephone customer a travel itinerary as they discuss it, or a broker might want to show a customer a visual confirmation of a financial transaction that the customer has just made orally over the telephone. Image data can be transmitted over a telephone line, for example, using conventional facsimile machines or the VoiceView.TM. products marketed by Radish Communications Systems, Inc. of Boulder, Colo. Alternatively, this data can be in the form of one or more data files to be transferred by modem between the parties' computers.

A number of telephone systems have been invented in the past to allow transmission of both voice and data over a single telephone line by switching between a voice mode and a single data mode, including the following:

______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ Davis 5,164,982 Nov. 17, 1992 Emmons et al. 4,932,047 June 5, 1990 Yoshida 4,815,121 Mar. 21, 1989 Cooper-Hart et al. 4,715,059 Dec. 22, 1987 Dumas 4,656,654 April 7, 1987 Artom 4,387,271 June 7, 1983 ______________________________________

Davis discloses a telecommunications display system for accommodating both voice and data over a single telephone line. The receiving party ("subscriber") is provided with a display terminal 14 that is connected to the telephone line 22, 52 between the telephone network 50 and the base of the user's telephone 12 as shown in FIG. 1 of U.S. Pat. No. 5,164,982. The display terminal includes a voice/data selector that can automatically recognize digital data and switches from voice communication to data communication modes. This patent discusses one embodiment of the VoiceView.TM. products marketed by Radish Communications Systems, Inc.

Emmons et al. disclose an example of a conversational video phone. The device communicates both audio signals and freeze-frame video images over a standard telephone line.

Yoshida discloses a telephone communication system that recognizes speech and automatically switches from data to speech transmission.

Cooper-Hart et al. disclose a conversational freeze-frame video phone that has been marketed by Luma Telecom, Inc. under the name "Luma." This system includes a camera for periodically capturing an image that is converted into digital data and transmitted over the telephone line to a remote unit in a single short burst. Audio transmission is interrupted upon detection of a video signal being transmitted. The data format and transmission rate for the video signal are fixed.

Dumas discloses a teleconferencing system that supports both audio and graphic communications. Each user has a personal computer (PC) with a smart modem that monitors the telephone line for a predetermined set of identification codes indicating that graphics are about to be sent by another conference participant. Here again, the data format appears to be fixed.

Artom discloses another example of a telephone system for combining voice and data communications over a single telephone line.

In addition to the prior art listed above, a number of modems and other telecommunications systems have been invented in the past that allow selection of multiple data formats or modes of communication that are established at the beginning of the call, including the following:

______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ Pan 3,423,534 Jan. 21, 1969 Parikh et al. 4,168,469 Sep. 18, 1979 Cain et al. 4,621,366 Nov. 4, 1986 Grenzebach et al. 4,661,657 Apr. 28, 1987 Levine et al. 4,876,740 Oct. 24, 1989 Greszczuk 4,931,250 June 5, 1990 Walsh 5,202,899 Apr. 13, 1993 Shirai et al. 5,182,762 Jan. 26, 1993 Kloc et al. 5,241,565 Aug. 31, 1993 Berland 5,282,238 Jan. 25, 1994 ______________________________________

The patent to Parikh et al. shows a data communications adapter to permit communications using the Synchronous Data Link Control format (SDLC).

Greszczuk discloses a multimode modem that sends a sequence of handshake signals corresponding to a variety of modem types, and then configures itself to operate in the mode indicated by the response received from the far-end modem. Walsh discusses another example of a similar system.

The modem disclosed by Shirai et al. negotiates the data transmission rate and data compression technique with the far-end modem during the initial handshaking procedure. The remaining references are only of general interest.

Finally, a number of modems and other telecommunications systems have been invented in the past that allow modems to exchange information concerning various features or data rates that are supported during an initial handshaking protocol, including the following:

______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ Hendrickson 4,001,504 Jan. 4, 1977 Bremer 4,663,766 May 5, 1987 Shih 4,727,370 Feb. 23, 1988 Copeland 4,782,498 Nov. 1, 1988 McGlynn et al. 4,905,282 Feb. 27, 1990 McGlynn et al. 4,953,210 Aug. 28, 1990 Hallman 5,146,472 Sept. 8, 1992 ______________________________________

The two patents to McGlynn et al. show a feature negotiation protocol for modems. The originating modem initiates negotiations by sending a list of supported features. The answering modem responds by confirming that all of the listed features are supported, by returning a subset of the features list, or by sending a different features list.

Copeland discusses a handshake procedure between modems for exchanging data such as device type, modes supported, speeds supported, signal quality conditions, etc.

The Walsh and Greszczuk patents listed previously are also relevant to this category of prior art. The modems described in these patents transmit an initial sequence of handshake signals corresponding to a variety of modem types. The modem then configures according to the response from the far-end modem.

The Bremer patent is an example of a modem with an automatic data rate selection feature. The remaining patents listed above are only of general interest.

3. Solution to the Problem

None of the prior art references show a telecommunication system providing automatic switching between voice and any of a plurality of data modes over a conventional telephone line using the present communications protocol. In particular, the present system allow the units to exchange information concerning their respective communications capabilities and the data modes that each unit supports. The units can then dynamically select different data modes throughout a conversation to transfer data in various formats.

SUMMARY OF THE INVENTION

This invention provides a telecommunication system for voice and data communications over a conventional telephone line that can be dynamically switched from voice mode to any of a plurality of data modes (e.g., fax, modem, or VoiceView protocols) during a single conversation. Each station includes a telephone for voice communications and switching means for selectively connecting the telephone to the telephone line in voice mode and disconnecting the telephone while operating in one of the data modes. A modem provides data communications over the telephone line in any of a plurality of data modes. Voice is the default mode of operation. Prior to switching into a data mode, the originating station first transmits a start signal over the telephone line that includes a mode signal indicating one of the data modes. If a station detects a start signal transmitted by a remote station, a controller directs the switching means and modem to automatically switch from voice mode to the selected data mode in preparation for receiving data from the originating station. The stations also can also query one another to exchange information on their respective capabilities.

A primary object of the present invention is to provide a telecommunication system providing automatic switching between voice and and any of a plurality of data modes over a single telephone line.

Another object of the present invention is to provide a telecommunication system that can dynamically select different data modes throughout a conversation to transfer data in various formats.

Yet another object of the present invention is to provide a telecommunication system that can be readily incorporated into a wide variety of data devices, such as modems, fax machines, and VoiceView products, and enables these devices to exchange information concerning their respective communications capabilities and the data modes that are supported.

These and other advantages, features, and objects of the present invention will be more readily understood in view of the following detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more readily understood in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of the overall invention showing communication between two stations over a telephone network.

FIG. 2 is a schematic block diagram of the data circuit-terminating equipment (DCE) 14.

FIG. 3 is a diagram of the signals transmitted by a DCE constituting the data mode start sequence.

FIG. 4 is a diagram of the mode tone (MTone) portion of the data mode start sequence.

FIG. 5 is a table of the different data modes for each combination of first and second tones shown in FIG. 4.

FIG. 6 is a diagram of an alternative embodiment of the data mode start sequence in which the mode tone sequence is replaced with data encoded in a V.21 HDLC frame to identify the data mode.

FIG. 7 is a diagram of a successful data mode start sequence between an originating DCE and an answering DCE using modem data mode (V.22bis protocol).

FIG. 8 is a diagram of a successful data mode start sequence between an originating DCE and an answering DCE using facsimile data mode (CCITT T.30 protocol).

FIG. 9 is a diagram of a capabilities query and response sequence for a DCE.

FIG. 10 is a diagram of a capabilities exchange sequence for a DCE.

FIG. 11 is a diagram of an unsuccessful data mode start sequence for fax or modem data mode in which the start sequence is rejected by the answering DCE.

FIG. 12 is a diagram of message format used for communicating capabilities information between DCEs.

FIG. 13 is a diagram of the format of the capabilities query message I-field.

FIGS. 14a through 14d are diagrams of the formats of capability elements within a capabilities query message for: (a) single octet format; (b) double octet format; (c) triple octet format; and (d) variable length format for 3 or more octets, respectively.

FIG. 15 is a table of the codings for the "capability type identifier" field in the capability elements shown in FIGS. 14a through 14d.

DETAILED DESCRIPTION OF THE INVENTION

Overview

Turning to FIG. 1, a schematic block diagram is provided showing two stations communicating over a telephone line 16, 26 via a public switched telephone network 50. Each station includes a conventional telephone set 12, 22 for voice communications. Data circuit-terminating equipment (DCE) 14, 24 is inserted between the telephone 12, 22 and the telephone network 50 to selectively couple the telephones 12, 22 for voice communications, and to selectively provide data communications in any of a variety of data formats, protocols, and/or transmission rates. The DCE 14, 24 is also tied to data terminal equipment (DTE) 10, 20, such as a personal computer for data communications. An RS-232 interface 13, 23 can be employed to connect the DCE 14, 24 to a serial port of the DTE computer system 10, 20. Alternatively, the DCE can be built in and attached via the internal bus of the DTE.

The present system can be employed, for example, by telemarketers, travel agencies, brokerage houses, financial institutions, or any other field of use where there is a need to share visual data during a telephone conversation. Such a telephone call is typically predominated by voice communications using the telephones 12 and 22. However, at desired times during the conversation, either party can momentarily interrupt the telephone conversation and transmit data over the telephone line to the remote station where it can be viewed and stored by the other party. For example, one station may include a database of products for sale, financial records, or airline schedule information that the party at the remote station wishes to see.

The telecommunication linkage is established in voice mode in the conventional manner by one party dialing the telephone number of the other party. The party at the central station accesses the database and generates a display screen 15 or creates a file containing the requested data. This can be accomplished using a DTE 10, such as a personal computer having a computer processor, a display screen 25, and a keyboard. At an appropriate time during the conversation, the party at the central station activates a data transmission command (e.g., by pressing a predetermined key combination on the computer keyboard, or by clicking a mouse on a predetermined icon on the computer display screen 15). The DTE processor 10 directs the DCE 14 to disconnect its telephone 12 and to transmit a start signal over the telephone line requesting that the remote DCE 24 switch to data mode. This start signal also indicates the format and transmission rate (the "mode") in which the data will be transmitted. Upon receipt of the start signal, the remote DCE 24 automatically disconnects its telephone 22 to temporarily suspend voice communications and configures itself to receive data in the specified mode. The data is then downloaded by the central station DTE 10 to its DCE 14, which modulates and transmits the data over the telephone line to the remote DCE 24. The remote DTE 20 uploads the received data from its DCE 24 and displays the data on its screen 25 for the remote user. Both stations automatically return to voice mode after the data has