WO2001019095A2 - Systeme de communication - Google Patents

Systeme de communication Download PDF

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Publication number
WO2001019095A2
WO2001019095A2 PCT/GB2000/003305 GB0003305W WO0119095A2 WO 2001019095 A2 WO2001019095 A2 WO 2001019095A2 GB 0003305 W GB0003305 W GB 0003305W WO 0119095 A2 WO0119095 A2 WO 0119095A2
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WO
WIPO (PCT)
Prior art keywords
communications
network
communications network
address
video
Prior art date
Application number
PCT/GB2000/003305
Other languages
English (en)
Other versions
WO2001019095A3 (fr
Inventor
Simon Christopher Gawne
Trevor John Coleman
Philip Geoffrey Claridge
Original Assignee
Initia Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Initia Inc. filed Critical Initia Inc.
Publication of WO2001019095A2 publication Critical patent/WO2001019095A2/fr
Publication of WO2001019095A3 publication Critical patent/WO2001019095A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/58—Arrangements providing connection between main exchange and sub-exchange or satellite
    • H04Q3/62—Arrangements providing connection between main exchange and sub-exchange or satellite for connecting to private branch exchanges
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/1307—Call setup
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13097—Numbering, addressing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13106—Microprocessor, CPU
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13166—Fault prevention
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13204—Protocols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13209—ISDN
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/1322—PBX
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/1328—Call transfer, e.g. in PBX
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13282—Call forward, follow-me, call diversion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13337—Picturephone, videotelephony
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13342—Arrangement of switches in the network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13389—LAN, internet

Definitions

  • the present invention relates to a communications system which is arranged to interconnect at least two communications devices, and in particular video communications devices.
  • the first type includes systems which use a combination of analogue (typically with touch tone signaling) and standard digital (e.g. on ISDN) or proprietary digital links to connect handsets.
  • analogue typically with touch tone signaling
  • standard digital e.g. on ISDN
  • PBX Public Switched Telephone Networks
  • POTS Plain Old Telephone Standards
  • LANs local area networks
  • PBX local area networks
  • a Gatekeeper or similar piece of hardware is required.
  • the PBX equivalent functions are split with the Gatekeeper providing the control functions and the LAN infra-structure providing the switching for the direct transfer of audio, video, and user-to-user data and call control information. While the Gatekeeper controls calls, voice and video is typically transferred directly between the end points, and not via the Gatekeeper. Thus, not only do such systems add to the cost of the network, but they do not offer the sophisticated call handling features that are available on standard PBX networks .
  • the bandwidth limitations are such that it is not possible to transfer high quality video images over such networks.
  • only low quality video images can be transferred using one of the ITU compression standards such as H.320 (for the transfer of video images over ISDN connections), or H.324 (for the transfer of video images over a POTS) , and these images are not of sufficiently good quality for use in video communications devices.
  • a method of operating a communications system having at least two communications devices, each communications device being coupled to first and second communications networks which operate in accordance with respective communications protocols, the method comprising, initializing communication by interconnecting the communications devices via the first communications network; and, once communication is established via the first communications network, further interconnecting the communications devices via the second communications network.
  • the present invention therefore provides a communications system which utilizes first and second communications networks to couple to respective communications devices.
  • This system allows communication to be established via a first communications network, with a second connection being subsequently established to allow further communication via a second communications network.
  • the system can also be used to establish a connection via the first communications network, and then allow all subsequent communication to be via the second communications network. This is particularly advantageous if the cost of using the first network is significantly higher than the cost of using the second network. This may happen for example if the second communications network is the Internet which allows cheap communications links to be established.
  • the method preferably further comprises attempting to re-connect the communications devices via the second communications network if a connection still exists via the first network. This ensures that should the transfer of data across the second communications network fail, then the communications devices will automatically attempt to reestablish the connection, thereby ensuring that the transfer is maintained.
  • An additional benefit of this is that any variations in the connections via the first communications network automatically result in corresponding changes in the connections via the second communications network.
  • any suitable method of ensuring the connection is maintained via the second communications network can be used.
  • each communications device has a respective first address associated with the first communications network.
  • the method of interconnecting the communications devices via the first communications network comprises causing a first communications device to transfer data and a provided first address to the first communications network, and causing the first communications network to transfer the data to a second communications device in accordance with the provided first address.
  • the first communications network transfers the data in accordance with the provided address thereby ensuring that the data reaches the intended destination.
  • any suitable method may be used.
  • the first communications network transfers data in accordance with the provided first address and one or more switching rules. These switching rules define the call handling features that are available on the first communications network.
  • the call handling features can be implemented. This allows the provided first address to differ from the first address of the communications device which ultimately receives the data, which may happen for example if the call is redirected, forwarded, transferred. Alternatively, however, any suitable form of routing may be used and it is therefore possible that the provided first address is the first address of the second communications device.
  • each communications device has a respective second address associated with the second communications network, wherein the method of interconnecting or reconnecting the communications devices via the second communications network comprises causing one of the communications devices to transfer its second address to the other communications device, via the first communications network, and causing the other communications device to transfer data to the one communications device via the second communications network, in accordance with the second address of the one communications device.
  • one of the communications devices may determine the second address of the other communications device from a look-up table stored in memory either within the communications device, or on either of the communications networks. This could be achieved by providing a look-up table in which the first and second addresses of each communications device are associated so that when one address is known, the other address can be looked up. Thus, once one of the communications devices is provided with the first address of a communications device, the second address of the communications device could be looked up.
  • the communications system operates to transfer video and audio data between the communications devices, and wherein the method of initializing communication comprises transferring audio data between the communications devices via the first communications network.
  • the method of initializing communication comprises transferring audio data between the communications devices via the first communications network.
  • any suitable data may be transferred between the communications devices over the first and second networks.
  • video data may be transferred over the second communications network using the ITU H.323 standard, or user-to-user data may be transferred using the ITU T.120 standard.
  • the method further comprises transferring video data via the second communications network. If video data is transferred via the second communications network and audio data via the first communications network, this can lead to problems of lip sync in that corresponding portions of audio and video data may take different times to travel between communications devices. In this case, the audio data will usually arrive prior to the video data. However, by transferring the video and audio data via the same second communications network this can lead to delays in the audio data which may make conversation awkward. Accordingly, either method may be used depending on the preference of the user.
  • a communications device for communicating via first and second communications networks, the device comprising: a first interface for coupling to the first communications network; a second interface for coupling to the second communications network; and, a processor coupled to the first and second interfaces, the processor being adapted to initialize communication by communicating with a second communications device via the first communications network, and once communication is established via the first communications network, to further communicate with the second communications device via the second communications network .
  • the present invention also provides a communications device for communicating via first and second communications networks. In this case the device includes first and second interfaces which operate to transfer data to the respective networks. A processor is also provided which controls the transfer of data onto the respective network.
  • This allows communication to be established via a first communications network, with a second connection being subsequently established to allow further communication via a second communications network.
  • this provides benefits regarding the transfer of high bandwidth data and the provision of call handling features, as well as having implications regarding the cost of communication.
  • the processor is adapted to monitor communication via the first and second communications networks, and if the processor determines that the connection via the second communications network is broken but that the connection via the first network still exists, the processor is adapted to attempt to re-connect the communications devices via the second communications network.
  • any method of ensuring that re- connection of the video communication is established may be used.
  • each communications device has respective first address associated with the first communications network, wherein the processor attempts to initialize communication by transferring data and a provided first address to the first communications network.
  • the provided address may be stored in a memory either on one of the communications networks, or within the communications device itself, and accessed by the processor as required.
  • the communications device includes an input for receiving the provided first address.
  • the provided first address may be stored in the communications device or on one of the communications network, with the address being retrieved when it is required.
  • each communications device has respective second address associated with the second communications network.
  • the processor is generally adapted to attempt to interconnect or re-connect to the second communications device via the second communications network by transferring its second address to the other communications device, via the first communications network, or by receiving the second address of the second communications device, via the first communications network, and transferring data to the second communications network, in accordance with the second address of the one communications device.
  • the communications device generally includes an input for receiving video and audio data, and an output for displaying video images and generating audible sounds corresponding to received video and audio data.
  • the video and audio data may be generated using a video camera and a microphone, or the like. Alternatively, however the video and audio data may be downloaded from a new recorded data source. Similarly, video images and audio signals may be output or alternatively, the data may be output to a store for subsequent play back at a later time.
  • a communications system for coupling two communication devices, the system comprising: first and second communications networks which operate in accordance with respective communications protocols; and, at least two communications devices each communications device being coupled to both the first and second communications networks the system being adapted to initialize communication by interconnecting the communications devices via the first communications network and, once communication is established via the first communications network, to further interconnect the communications devices via the second communications network .
  • the present invention also provides a communications system for coupling to communications devices. This utilizes first and second communications networks which operate to transfer respective data as set out above.
  • the first communications network comprises at least one of a PBX network, a PSTN or a POTS. This is particularly advantageous as these networks allows sophisticated call handling as part of their normal operation. However, any suitable network, or a combination of any of the above, may be used.
  • the first communications network transfers data in accordance with one or more switching rules which define call handling features, including call transfer, call re-direct and call forward.
  • any suitable switching rules may be used.
  • the second communications network comprises at least one of a LAN, a WANs or the Internet.
  • the advantage of using a network such as a LAN or a WAN, or the Internet is that these provide a high available bandwidth allowing high quality video images to be transferred in real time.
  • the Internet advantageously allows global communication to be achieved relatively cheaply, using an existing network infrastructure.
  • the LAN or WAN will usually operate in accordance with a communications protocol such as the Token Ring, ATM or Ethernet Protocols.
  • the second address would comprise an IP address.
  • any suitable communications network may be used, and this may depend on the data to be transferred. Examples of the present invention will now be described with reference to the accompanying drawings, in which: -
  • Figure 1 is a schematic view of a first example of a communications system according to the present invention
  • Figure 2 is a schematic diagram of a modified version of the communications system of Figure 1 ;
  • FIG 3 is a schematic diagram of a second example of a communications system in accordance with the present invention
  • Figure 4 is a schematic diagram of a third example of a communications system in accordance with the present invention.
  • Figure 5 is an example of a communications device suitable for use in the communications systems of Figures 1 to 4.
  • Figure 1 shows a communications system including first and second end stations A,B coupled together via a PBX type network 1 and a LAN 2.
  • the PBX type network could be either a standard PBX, a POTS or a PSTN
  • the LAN 2 can be any LAN, WAN or communications network which is capable of transferring video data.
  • the communications network may be a Token Ring, ATM, or Ethernet network or the Internet .
  • Each end station A,B is designed to operate as a video phone and may be formed from either a computer modified with appropriate input and output devices, or a specialized unit.
  • Each end station A,B includes an input device 10 and an output device 13, each of which is coupled via a bus 11 to a microprocessor 12.
  • the processor 12 is coupled to a memory 14 which operates to temporarily store data which is to be transferred or which has been received from the PBX network 1 or the LAN 2.
  • the processor 12 is coupled to the PBX network 1 via a bus 15 and a PBX interface 16, and to the LAN 2 via the bus 15 and a LAN interface 17.
  • the input device 10 will include a video camera, a microphone, and a keyboard (not shown)
  • the output device 13 will include a VDU and a speaker. This allows video images, audio signals and user commands to be input to and output from the respective end station A,B.
  • Each end station A,B also has a unique PBX address and a unique LAN address which allows data to be transferred thereto, via the respective PBX network 1 or LAN 2.
  • Each end station will typically store its own respective addresses either in the memory 14 or within the respective PBX or LAN interfaces 16,17.
  • the general operation of the end stations A,B to transfer data is as follows.
  • audio and video information is input into the input device 10, this is transferred via the bus 11 to the processor 12.
  • the processor 12 separates the data into data which is to be transferred via the PBX network 1 and data which is to be transferred via the LAN 2. This will generally comprise audio and video data respectively.
  • Any data which is to be transferred immediately is then directed via the bus 15 to either the PBX or LAN interface 16,17, otherwise the data is temporarily stored in the memory 14, until it is transferred.
  • Data received by the PBX interface 16, from the processor 12, is modified so that it is in a suitable format for transfer over the PBX network 1.
  • the data is then output onto the PBX network 1, and transferred across the PBX network 1 in accordance with the PBX address contained in the packet header.
  • any data to be transferred onto the LAN 2 is sent to the LAN interface 17.
  • the data is segmented into data packets and an appropriate data packet header is added including the LAN address of the intended destination end station A,B.
  • the data is transferred to the PBX interface 16 or the LAN interface 17 respectively.
  • the data is modified as required before being transferred via the bus 15 to the processor 12.
  • the processor 12 transfers the video and audio data to the output device which displays video images representative of the video data on the display, whilst the audio data is used to generate audio signals from the speaker.
  • each end station has both audio and video capabilities, and are attached to both the PBX network 1 and the LAN 2, it is possible for each end station to make calls in any of the following ways:
  • Voice calls via the PBX emulating a standard voice only handset (the LAN is unused) .
  • Video calls via the PBX using low bandwidth video conferencing standards such as H.324 or H.320 (the LAN is unused) .
  • Hybrid video calls where at least the initial voice call is routed via the PBX, and the LAN is used to supplement the bandwidth, in accordance with the present invention.
  • Operation of the system of Figure 1 to allow a hybrid video call to be made from the end station A to the end station B, in accordance with an example the present invention, will now be described.
  • the user initiates the call as a standard audio only call via the PBX network 1.
  • the end stations A,B operate as conventional audio only end stations, such as telephones, and the LAN is not used. For example, if the user is to initiate the call from end station A, then the end station A will require the PBX address of the end station B.
  • PBX address typically takes the form of a standard telephone number or the like, of the end station B, via the input device 10.
  • the PBX address may be stored in the memory 14 and simply accessed by the processor 12 of the end station A, as required.
  • the processor 12 then initiates a normal telephone call by transferring a call set-up message onto the PBX network 1, the message including the PBX address of the end station B, in the usual way.
  • the processor of the end station B and alerts the end station user via the output device 13. Once the user indicates that the call is to be accepted, for example by picking up a handset, this completes the connection of the two end stations A,B via the PBX network 1.
  • the user can carry out a normal telephone conversation via the PBX network 1. This is achieved by having any audio information input into one of the end stations A,B, transferred to the other end station B,A, via the connection over the PBX network 1. Once communication is established via the PBX, the end stations can then operate to further transfer video data.
  • the triggers that can cause the end stations to transfer video data include: 1. The end station answering an incoming call from the
  • PBX network 1 could automatically cause the end station to attempt video communication.
  • the user In the case in which the user requests that the call be extended to include video communication, the user will input a command via the input device 10. This command is transferred via the bus 11 to the processor 12, which determines that a video connection is required. In the other cases, the fact that a video connection is required is determined automatically by the processor 12 of at least one of the end stations A,B.
  • the end stations A,B When it is first determined that a video connection is required, the end stations A,B will not necessarily have the LAN address of the other end station B,A (this depends on the way in which the LAN address are exchanged which is described below) . If this is the case, the system operates to cause at least one of the end stations A,B to determine the LAN address of the other end station B,A.
  • the end stations A,B can exchange or infer the LAN address of the other end station B,A using one or more of the following mechanisms as appropriate for the PBX in use
  • An entity on the LAN may have a look-up table of the PBX and corresponding LAN addresses of called end stations. Accordingly, the called end station (the end station B) can use the PBX address received from the calling end station (the end station A) via the PBX network 1 to look-up the LAN address of the calling end station A. 2.
  • the LAN address can be carried between the stations using end-to-end information fields in the call set-up message data. Typically this is available on digital PBX networks only, for example in the User-User information element defined within call set-up message data of the Q.931 ISDN standard (see section 4.5 of ITU Q.931 standard March 1993 edition) .
  • the LAN address of the other end station B,A will be known by the end station A,B, when the requirement for a video connection is determined. 3.
  • the LAN address can be carried once the call is established via end-to end control messages. Again, this is typically available for digital PBX networks only. (For example the ISDN User Information message of the Q.931 ISDN standard see section 3.3.13 of ITU Q.931 standard March 1993 edition).
  • the LAN address can be carried in the audio channel established between the stations.
  • the simplest most robust (but also most invasive solution) is to use touch tone to signal the digits.
  • Faster less obtrusive alternatives include older modem standards that require little or no line equalisation or training (e.g. V.21, V.22).
  • the audio channel is an all digital connection the address can be exchanged by directly embedding the LAN address in the digital data passed between the end stations.
  • the information When the LAN address is sent digitally in the audio data over a digital audio link, the information will typically also include some form of pattern that can be used to recognize the presence of information and some form of error correction or detection to ensure that the address is valid.
  • the LAN address would typically be sent more than once, and may only use the less or least significant bits of the audio channel to minimize audible intrusion of this data. Where the intrusion is noticeable then the signaling can be blanked from being sent to the end user (either by muting the first period of the call or detecting the incoming information and muting the audio out) . There is no reason that the end station LAN address should not be sent throughout the call over the audio channel, though this is not required by the present invention.
  • either one of the end stations A,B may operate to determine the LAN address of the other end station B,A.
  • both of the end stations A,B can try to exchange LAN addresses, thereby completing the call in parallel.
  • the end station on which the request for a video connection has been made either transfers its own LAN address to the other end station, or operates to look-up the address of the other end station from the entity on the LAN 2.
  • At least one of the end stations A,B receives or determines a LAN address of the other end station B,A, it will operate to initiate video communication.
  • the processor 12 of the respective end station A,B will generate a signal which is to be transferred via the bus 11 to the output device 13, indicating to the user that video communication is to be established.
  • the input device 10 will then be activated to generate video images which are transferred via the bus 11 to the processor 12.
  • the processor 12 then transfers the video data via the bus 15 to the LAN interface 17.
  • the data is segmented and placed in the required transmission format before being transferred onto the LAN 2.
  • the video data is transferred over the LAN 2 in accordance with the LANs normal transmission protocol .
  • the other end station B,A will then receive the video data via the LAN interface 17.
  • the video data is transferred via the processor to the output device for display as a sequence of video images .
  • the end station B,A which receives the video data will then determine the LAN address of the other end station A,B, thereby allowing video data to returned to the other end station. This may be achieved by any of the methods outlined above or, alternatively, at least one of the first video data packets received by the end station B,A will include the LAN address of the other end station A,B.
  • An alternative solution which avoids the requirement for transfer of the LAN address is for the end station A which initiates the call to monitor the input PBX address and use a parallel set of routing information to place a parallel call over the LAN 2. This can fail however, if the PBX re-routes calls based on destinations being busy or more complex routing algorithms (as may be used in call centres) . Should the connection via the LAN 2 fail, then the end stations are configured to attempt to re-establish the connection. This is done by causing one or more of the end stations A,B to re-determine the LAN address of the other end station B,A. The above described process can then be repeated to re-establish the connection via the LAN 2.
  • the system described above allows video data to be transferred via the LAN 2 whilst call set-up is controlled by the PBX network 1.
  • a further benefit of this system is however that causing the end stations A,B to attempt to reconnect when a connection over the LAN 2 fails, causes various call handling features available on the PBX network 1, to be automatically implemented for the video connection via the LAN 2.
  • the preferred operation of the system to provide hybrid video calls for the example of the end station A calling the end station B, can be summarized by the following steps: 1.
  • the end stations A,B connected to the LAN 2 have respective LAN addresses (typically an IP address) .
  • the end station A calls the end station B via the PBX network 1 using signaling native to the PBX (i.e. the end station A appears to the PBX as a conventional end station and the LAN 2 is not used) .
  • the end station A passes its LAN address to the end station B (in some PBX this information may be implicitly inferred rather than explicitly sent) .
  • the end station B then establishes a LAN connection with the end station A (typically using standard IP address location mechanisms) , undertakes some basic validation (e.g. both stations are capable and wish to make a video call, typically using mechanisms within the H.323 standard), and establishes parallel audio, video and/or user-to-user data connections.
  • a LAN connection typically using standard IP address location mechanisms
  • some basic validation e.g. both stations are capable and wish to make a video call, typically using mechanisms within the H.323 standard
  • establishes parallel audio, video and/or user-to-user data connections typically using mechanisms within the H.323 standard
  • FIG. 2 shows a modification of the communication system of Figure 1 in which a third end station C has been added.
  • communication can be established between any of the end stations A,B,C in the manner described above with respect to Figure 1.
  • the user of end station A can simply enter a call forward command via the input device 10, the command including the PBX address of the end station C.
  • the PBX therefore follows its normal operating protocols so as to disconnect the call from the end station A and reconnects the call to the end station C. This is achieved by breaking the connection between the end stations A,B and simultaneously establishing a new connection between the two end stations B,C, in the manner described above.
  • the two end stations B,C now communicate via the PBX network 1 and as a result, the end station B is unaware that the connection via the PBX network 1 has been modified.
  • the end station 1 continues to transfer and receive audio data via the PBX network 1, whilst the end station A determines that the call has finished and accordingly ceases to transmit video images .
  • the end station B is therefore no longer receiving any video data from the end station A, even though a connection over the PBX network 1 is still present.
  • the end station B determines that the video connection over the LAN 2 has failed and attempts to reconnect the video connection via the LAN 2.
  • the end station B will use one of the abovementioned methods to allow one of the end stations B,C to determine the LAN address of the other end station C,B. Video communication will then occur between the two end stations B,C in the manner described above.
  • the end station B will use the PBX address of the end station A to determine a corresponding LAN address. Accordingly, when the call is transferred, it is necessary for the look-up table to be modified to associate the LAN address of the end station C with the PBX address of the end station A. This would be a temporary association such that the end station B can determine the LAN address of the end station C from the PBX address of the end station A.
  • the simple transfer procedure is as follows : 1.
  • the end stations A,B connect as described above and establish a parallel video connection.
  • the end station A signals to the PBX (using standard PBX voice protocols) that it wishes to transfer the call to end station C.
  • the end station A clears the corresponding video call.
  • the end stations B,C exchange their LAN addresses via the PBX and make a parallel video connection.
  • An alternative call control function is call forward.
  • video communication can be initiated as described above.
  • the end station A attempts to connect with the end station B.
  • the PBX connects the end station A to the end station C.
  • the end stations A,C transfer LAN addresses and establish a parallel connection via the LAN 2.
  • a further option is 3 way operation which is achieved as follows:
  • the end stations A,B connect as described above and establish a parallel video connection.
  • the end station A signals to the PBX (using standard PBX voice protocols) that it wishes to include the end station C in the call.
  • the voice call is made to the end station C, the PBX is assumed to normally provide audio mixing functions.
  • the end stations A,C exchange their LAN addresses via the PBX network 1, make a parallel video connection via the LAN 2, and may also request internal or external video mixing (MCU) resource to allow 3 way video images between the three stations.
  • MCU video mixing
  • the end station C typically answers an incoming call from the PBX and then sends its LAN address to the end station A via the PBX network 1.
  • any signaling of the LAN address over the audio connection may have to be intrusive to pass through the audio mixer (audio mixers typically mute audio input below a certain level) .
  • FIG. 3 is shown in Figure 3.
  • a Gatekeeper 3 is coupled to the LAN 2.
  • the Gatekeeper 3 operates to provide normal call control, billing and security features that are provided on a LAN.
  • each end station A,B must register its respective LAN address with the Gatekeeper, which then operates in the normal way.
  • One of the end stations A,B requests a call token (a digital LAN address) from the Gatekeeper, via the LAN, when a call is sent or received via the PBX network 1.
  • a call token (a digital LAN address) from the Gatekeeper, via the LAN, when a call is sent or received via the PBX network 1.
  • the station requesting the token would pass its LAN address to the Gatekeeper. 2.
  • the token is then sent through the PBX network lusing the techniques described above .
  • the token is returned to the Gatekeeper via the LAN 2, from the end station B,A that receives the token, together with the LAN address of the end station that received the call .
  • the Gatekeeper has all of the end station LAN addresses and can validate if a video call is allowed, can then directly initiate the video call, or instruct one of the end stations to initiate the video call.
  • the system can be extended to include a Gateway to allow communications with external networks.
  • a Gateway to allow communications with external networks.
  • An example of such a system is shown in Figure 4.
  • the system includes an end station D which is not video equipped and can therefore only handle audio only calls, and a Gateway 4, as shown.
  • the operation of such a system to receive an incoming call is as follows.
  • An external video/audio call from a distant end point arriving at the Gateway 4 would be separated into audio and video components.
  • the audio component would be sent over a trunk interface to the PBX network 1 (typically primary rate ISDN) .
  • the video component of the call would be held (and a video status message could be sent by the Gateway 4 to the distant caller) .
  • the PBX network 1 would route the call to the video equipped end station B or he non-video equipped end station D.
  • the non-video equipped end station D communicates via the PBX network 1 only and the Gateway can provide dummy video if required to the distant caller.
  • the video equipped end station B and the Gateway could exchange LAN addresses, as described above, and make an additional video connection. It should be noted that while the Gateway can handle multiple incoming calls it can differentiate between the different LAN address that may be exchanged by referring to the address of the channel on the trunk connection used between the Gateway 4 and the PBX network 1.
  • the called number passed to the PBX network 1, from the Gateway 4 could be prefixed to that the PBX network 1 selects video equipped end stations in preference to non-video equipped end stations D.
  • non-video equipped end stations such as the end station D shown in Figure 5
  • the end station D communicates with a video equipped end station A,B,C the call set up will occur in the normal way as described above.
  • the end station A,B,C D will be unable to determine the LAN address of the end station D. Accordingly, the end station A,B,C will simply function as a non-video equipped end station, allowing basic audio communication to continue uninterrupted.
  • lip sync may be overcome by identifying respective audio and video data packets and ensuring that the receiving end station processes corresponding data packets simultaneously thereby ensuring that the corresponding audio and video data packets are output to the user simultaneously.
  • the PBX network 1 or the LAN 2 could be replaced by a number interconnected networks , in any of the above examples.
  • the PBX network 1 could be replaced by one or more separate networks including any of a PBX, a POTS and/or a PSTN, as long as the networks are arranged to allow connections to be established between any of the end stations A,B,C,D, which may be coupled to any of the networks.
  • the LAN 2 could be replaced by a number of interconnected LANs and/or WANs, including the Internet, which also allow data to be transferred between end stations coupled to the different networks.

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  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Small-Scale Networks (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Communication Control (AREA)

Abstract

L'invention concerne un procédé d'exploitation d'un système de communication doté d'au moins deux dispositifs de communication (A, B). Chaque dispositif de communication (A, B) est couplé à un premier et à un deuxième réseau de communication (1, 2) qui fonctionnent selon des protocoles de communications respectifs. Ledit procédé consiste à initialiser la communication par l'interconnexion des dispositifs de communication, par l'intermédiaire du premier réseau de communication (1). Une fois la communication établie, les dispositifs de communication sont interconnectés par l'intermédiaire du deuxième réseau de communication (2).
PCT/GB2000/003305 1999-09-06 2000-08-25 Systeme de communication WO2001019095A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9921038.7 1999-09-06
GBGB9921038.7A GB9921038D0 (en) 1999-09-06 1999-09-06 Communication system

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WO2001019095A2 true WO2001019095A2 (fr) 2001-03-15
WO2001019095A3 WO2001019095A3 (fr) 2001-10-11

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GB (1) GB9921038D0 (fr)
WO (1) WO2001019095A2 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996016497A1 (fr) * 1994-11-21 1996-05-30 Oracle Corporation Transfert de grands objets binaires en environnement reseau
FR2753862A1 (fr) * 1996-09-26 1998-03-27 Tebeka Henri Procede et systeme de communication interactive entre deux appareils telephoniques via le reseau internet
WO1998037665A1 (fr) * 1997-02-02 1998-08-27 Fonefriend Systems, Inc. Boite de commutation internet, systeme et procede de telephonie par internet

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996016497A1 (fr) * 1994-11-21 1996-05-30 Oracle Corporation Transfert de grands objets binaires en environnement reseau
FR2753862A1 (fr) * 1996-09-26 1998-03-27 Tebeka Henri Procede et systeme de communication interactive entre deux appareils telephoniques via le reseau internet
WO1998037665A1 (fr) * 1997-02-02 1998-08-27 Fonefriend Systems, Inc. Boite de commutation internet, systeme et procede de telephonie par internet

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GB9921038D0 (en) 1999-11-10

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