GB2335110A

GB2335110A - Data communication

Info

Publication number: GB2335110A
Application number: GB9804857A
Authority: GB
Inventors: David Goadby
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-07
Filing date: 1998-03-07
Publication date: 1999-09-08
Also published as: GB9804857D0

Abstract

A data communication method which can securely and reliably send, and receive, binary data streams consisting of any pattern of 1's and 0's, of any length, between two or more devices over any telephone system, which incorporates Caller Line Identification (CLI), without requiring the called device to go OffHook. The two required signaling states are determined by the existence or absence of the CLI message which is controlled by the calling device dialing the codes dictated by the Telecommunications Carrier.

Description

/1- 2335110 DATA COMMUNICATION METHOD USING THE TELEPHONE SYSTEM This

invention relates to a method of communication between electronic devices using a telephone system.

Many established methods are used to communicate information between electronic devices using telephone connections. Such methods include Modulator Demodulators (MODEMS) for Public Switched Telephone Network (PSTN) systems and special adapters for digital circuits such as Integrated Services Digital Network (ISDN). All of these systems work by the calling system dialing the required device which, upon receiving the ringing signal, connects to the telephone line by changing it's state to OffHook. At this time there is a sequence of messages exchanged between the caller and called devices that form the basis of the connection. After completion of the data exchange either or both of the devices will cancel the connection by changing status to On Hook.

The above method has one drawback in that the state change from On Hook to Off Hook in response to the ringing signal results in the Telecommunications Carrier levying a connection charge. This charge is followed by further online charges. Even lines which are ftee of charge for the caller are paid for by the called party. No connection is free of charges in both directions.

This invention provides a two way communication method which incurs no charges by either the calling or called device by using the information contained within the Caller Line Information (CLI). The CLI data is placed on the telephone line by the Telecommunications Carrier just before the ringing signal. The CLI data contains, amongst other things, the callers' telephone number and is meant to be extracted and decoded for purposes such as call filtering and automatic lookup of caller details. The caller's telephone number element of the CLI signal can usually be disabled by the caller. In the United Kingdom the caller dials 147 1. This invention uses the ability of the caller to enable and disable the CLI to create a stream of digital data where the existence of the CLI is taken to be one state e.g. a binary 1 and the absence of the CLI is taken to be the opposite state e.g. a binary 0. Thus, it is possible to send a complete message using the CLI. Similarly the called device can respond to the callina device by similar means.

The calling device will consist of a minimum of a dialing module and a source of data. A called device will consist of a minimum of a CLI detector module and line answering module. A diagram outlining a typical device capable of acting as either a called or calling device is shown in Figl.

2 The following sequence illustrates a possible use of the invention whereby the calling device sends the binary code 1010 to the called device which is at telephone number 0123-45678 using the existence of CLI to represent a '1' and the absence of the CLI to represent a binary V. The code 1461 is used to enable CLI and the code 1471 is used to disable CLI. The CLI codes are representative only and do not indicate the actual codes required for any particular Telecommunications Carrier.

1. The calling device transmits a 'I 'by dialing 1461 0123-45678. Once the calling device has detected a ringing tone or, after a predetermined time which is sufficient for the called device to ring at least once, the calling device rings off.

The called device detects CLI containing 0123-45678 which is decoded to mean data value '1' from calling device 0123-45678. The called device logs the d but does not answer the phone and stays On Hook.

The calling device now transmits a '0' by dialing 1471 0123-45678. Once the calling device has detected a ringing tone or, after a predetermined time which is sufficient for the called device to ring at least once, the calling device rings off.

4. The called device detects CLI containina no number which is decoded to mean a data 0 value '0' from calling device 0123)-45678. The called device logs the 0 but does not answer the phone and stays On Hook.

To send another '1' to the called device the step 1 above is repeated.

6. To send another '0' to the called device the step 3 above is repeated.

7.

Afler each transmission the called device detects and logs the transmitted code value.

8. The sequence is now complete and the called device my respond to the calling device with codes resulting from the received message. Since the telephone number of the calling device is in the CLI the called device already knows where the message came from.

The sequence is further illustrated in the example in Fig2.

3 The method can be used to send data of any type or size from one or more calling devices to one or more called devices.

The present invention allows a data device to share a telephone line with another, secondary, telephone device such as a telephone, Fax or Modem, by only allowing the secondary telephone device to ring after a predetermined number of ringing signals have been received. This facility is provided by the connection (Cl) to (C6) in Figl whereby the Data Connection circuit inhibits the passing of the ringing signal from (C4) to (C6) until such time as the controlling device permits or requires it.

If secondary telephone devices are attached then the data integrity of this invention is assured even if one of the attached devices is answered (off hook) before, during or after data transmission. If a secondary telephone device is off-hook before transmission, the calling device will get a busy (engaged) signal and will retry later. If the secondary telephone device is placed off-hook in response to the ringing the data has already been received.

Although is it possible for the system to be corrupted by unintentional, or intentional, callers dialing the Called Device with the CLI disabled, the use of mathematical error checking and correcting systems such as Parity, Hamming Code and Cyclical Redundancy Checking will ensure data integrity.

4 CLA11MS 1. A communication method whereby a calling device can reliably send data consisting of a stream of binary I's and O's to a selected receiving device without the receiving device selecting On Hook status.

2. A communication method as claimed in 1 whereby the identity of the sender of an information stream of binary I's and O's can be determined by the called device using the data in the CLI message.

A communication method as claimed in 1 whereby a previously called device can reliably send a response to the calling device with data consisting of a stream of binary I's and O's to the sending device without the sending device selecting On Hook status.

A communication method as claimed in 1 whereby a single Master calling device may send and receive a binary message stream to one or more slave receiving devices.

7Z A communication method as claimed in 1 whereby a number of Master calling devices Z:) my send and receive a binary message stream to one or more slave receiving devices.

6. A communication method as claimed in 1 whereby the data stream consists of a sequence of binary I's and W. The data stream may be from 1 to any number of units in length.

7. A communication method as claimed in 1 whereby the received data contains the identity of the sender of the data in order that the called device may respond.

8.

10.

A communication method as claimed in 1 and 7 whereby the received data contains the identity of the sender of the data which can be used for secure data transmission.

9. A communication method as claimed in 1 whereby any number of secondary telephone devices can be connected to the same telephone line as either the Calling or Called devices without restricting their functionality.

A communication method as claimed in 1 and 9 whereby the secondary telephone will not ring unless required to do so and, as a consequence, the data transfer is non-intrusive.

11. A communication method as claimed in 1 and 10 whereby the data transfer is undetectable.

A communication method as claimed in 1 and 9 and 11 whereby the data transmission integrity is maintained even if an attached telephone device is inadvertently picked up W (answered).