Video conferencing network

• US 4,710,917 A
• Filed: 04/08/1985
• Issued: 12/01/1987
• Est. Priority Date: 04/08/1985
• Status: Expired due to Term

• Current Assignee: Datapoint Corp. (Dynacore Holdings Corporation)
• Original Assignee: Datapoint Corp. (Dynacore Holdings Corporation)
• Inventors: Arends, Thomas C., Barry, Michael W., Tompkins, E. Neal
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Chin, Wellington
• Application Number:
  US06/721,281
• Time in Patent Office: 967 Days
• Field of Search: 370/62, 370/110.1, 370/58, 370/71, 370/73, 370/124, 370/76, 179/18 BC, 179/2 TV, 179/2 TS, 358/85, 379/202, 379/204, 379/206
• US Class Current: 709/204
• CPC Class Codes: H04M 3/561 by multiplexing
• CPC Class Codes: H04Q 11/04 for time-division multiplexing H04Q11/0001 takes precedence

Abstract

A video conferencing network includes remote video terminals (10) interconnected to a switching network (66) through coaxial cables (16). The switching network (66) is operable to provide an audio and video data path between two or more video terminals (10). The switching network (66) operates as both an audio/video crosspoint switch and also as a network controller. In the network control mode, the switching network (66) operates in both a master mode for maintaining data communication with all of the video terminals (10) and also in a slave mode for maintaining status of devices attached to the switching network (66). In the master mode, the switching network (66) receives requests from each of the video terminals (10) and services these requests to determine available data paths for interconnection with other video terminals. In the slave mode, the switch (66) is in data communication with all of the video terminals (10) to determine the status thereof which is stored in a slave status table. This information in the status table is transferred to a separate network table that is maintained in the master mode for network purposes.

Claims

1. A video conferencing network, comprising:

a plurality of video terminals each having a unique address for transmitting and receiving audio, video and data;

switching means for receiving audio and video information at one of a plurality of audio/video ports and selectively transmitting said received audio and video information to one or more of the remaining of said audio/video ports;

data manager means for receiving data at one of a plurality of data ports, determining which of the remaining of said data ports the received data is to be transmitted to in accordance with predetermined routing information and transmitting the received data to the determined one of said data ports;

communication link means disposed between each of said video terminals and a select one of said audio/video ports on said switching means and a select on of said data ports on said data manager means;

slave means for controlling the configuration of said switching means in response to receiving a reconfiguration signal from said data manager means, said slave means in data communication with a select one of said data ports on said data manager means;

network master means for cotnrolling the network, said network master means receiving data from said data manager means and transmitting data thereto, said network master means communicating with said video terminals and said slave means, said network master means generating said reconfiguration signal for transmission to said slave means through said data manager means to reconfigure said switching means; and

data link means for interfacing between said network master means and one of said data ports on said data manager means.

2. The network of claim 1 wherein said switching means comprises:

audio multiplexer means for receiving audio from all of said audio/video ports and summing audio from select ones of said ports in accordance with said reconfiguration signal for transmission to one or more of the remaining of said audio/video ports; and

video multiplexing means for receiving video from each of said audio/video ports and selectively connecting the received video from one of said ports to one or more of said audio/video ports such that only one of the received video signals is transmitted to any one of said video terminals.

3. The network of claim 1 wherein said communication link means comprises:

a transmission medium associated with one of said video terminals, one of said audio/video ports on said switching means and one of said data ports on said data manager means;

first encoding means associated with each of said video terminals for receiving audio, video and data from the associated one of said video terminals and encoding it in a predetermined manner for transmission along a first path in said transmission medium, said first encoder means receiving encoded audio, video and data from a second path in said transmission medium and outputting decoder audio, video and data to the associated one of said video terminals; and

second encoding means for receiving encoded audio, video and data from said first path in said transmission medium and outputting decoded audio and video to said switching means and decoded data to said data manager means, said second encoding means receiving audio and video from said switching means and data from said data manager means and encoding said received audio, video and data in said predetermined manner and transmitting it on said second path in said transmission medium.

4. The network of claim 3 wherein said transmission medium includes a third bidirectional path for carrying information not associated with the network, information carried on said third path isolated from information carried on said first and second paths that is associated with the network.

5. The network of claim 3 wherein said transmission medium comprises a coaxial cable and said predetermined encoding pattern comprises frequency division multiplexing.

6. The network of claim 5 wherein said first and second encoding means comprise:

means for demodulating the encoded transmission to separate the transmitted audio, video and data information; and

means for receiving audio, video and data information and modulating a carrier frequency for transmission through said coax.

7. A video conferencing network, comprising:

a plurality of remotely disposed video terminals for transitting and receiving audio, video and data and each attached to one of a plurality of network ports, each of said network ports for receiving and transmitting audio, video and data;

switch means for receiving audio and video from each of said network ports and interconnecting the received audio and video for transmission to select ones of said network ports in accordance with a predetermined interconnect pattern;

data manager means for receiving data from each of said network ports, identifying the destination of the received data, and routing the received data to the one of said network ports corresponding to the identified destination;

slave means attached to one of said network ports for reconfiguring said switch means in accordance with said predetermined interconnect pattern, said slave means controlled by data received from said data manager means;

network master means attached to one of said network ports for controlling the operation of the network, said network master means operable to transmit data to and receive data from said data manager means to establish communication with said video terminals and said slave means, said network master means generating said predetermined interconnect pattern for transmission to said slave means through said data manager means; and

communication link means for interfacing said switch means and said data manager means with said network ports.

8. The video conferencing network of claim 7 wherein each of said remote terminals comprises:

camera means for converting an image to a video signal;

display means for receiving a video signal and converting it to an image;

microphone means for receiving audio information from a transmission medium associated with each of said remote terminals and converting it to an audio signal;

speaker means for receiving an audio signal and converting it to sound information for transmission through said associated transmission medium;

audio/video multiplex means for receiving the locally generated audio and video signals and the audio and video signals from the associated one of said network ports and routing the received signals to either said display means, said speaker means or the associated one of the said network ports; and

control means for controlling said video terminal and the operation thereof and for data interface with said network master means through said data manager means.

9. The network of claim 8 wherein said audio/video multiplex means comprises:

an audio multiplexer for receiving the audio signals from said microphone means and from the associated one of said network ports and for selectively transmitting received audio to either said speaker means or to the associated one of said network ports; and

a video multiplexer for receiving a video signal from said camera means and from the associated one of said network ports and for selectively interconnecting the received video with said display means or with the associated one of said network ports.

10. The network of claim 8 and further comprising preview display means for receiving of video signals from said audio/video multiplexing means and converting the received video to video images, said preview display means having a surface area less than that of said display means.

11. The network of claim 8 wherein said control means is operable to control said video terminal to receive video from the associated one of said network ports and inhibit transmission of Video thereto.

12. The network of claim 8, and further comprising interface means for interfacing with an external local processor for utilizing said external local processor to increase the processing capacity of said video terminals, said interface means operable to receive video signals from said external local processor for input to said audio/video multiplexing means.

13. The network of claim 7 wherein said video terminals operate asynchronously with respect to data communication on the network, said video terminals communicating with said network master means to gain access to other of said video terminals on the network or to allow access from other of said video terminals on the network.

14. The network of claim 7 wherein said predetermined interconnect pattern contains information for said switch means to interconnect select ones of said video terminals in a conference with said switch means receiving video from each of said video terminals in the corresponding conference and transmitting only one of the received video signals to any one of said video terminals in the corresponding conference in accordance with a predetermined priority pattern generated by said network master means, said switch means receiving audio from each of said video terminals in the corresponding conference and summing the received audio for each of said video terminals in the corresponding conference for transmission thereto with the exception of the video generated by the receiving one of said video terminals such that each of said video terminals in the corresponding conference receives only summed audio from the others of said video terminals in the corresponding conference.

15. The network of claim 14 wherein said priority pattern generated by said network master means designates one of said video terminals in the associated conference as a primary video terminal with the video from said primary video terminal received by the remaining of said video terminals in the associated conference and one of said video terminals in the associated conference as a secondary video terminal with the video from said secondary video terminal received by said primary video terminal, the remaining of said video terminals in the associated conference designated as m-ary video terminals, said priority pattern generated only when three or more of said video terminals are in a conference, each of said video terminals operable to transmit a request to said network master means to become said primary video terminal such that said network master means updates the priority status of the requesting one of said video terminals to primary and degrades the status of the prior said primary video terminal to said secondary video terminal and the prior said secondary video terminal to one of said m-ary video terminals.

16. The network of claim 15 wherein each of said video terminals generates the request for primary status in response to receiving voice information from the user of said workstation, said voice being present for a predetermined amount of time.

17. The network of claim 15 wherein each of said video terminals further comprises means for generating a conference lock signal for transmission to said network master means, said network master means inhibiting alteration of said priority pattern upon receipt of said conference lock signal by one of said video terminals such that one of said video terminals generating said conference lock signal has the status thereof updated to said primary video terminal, said status maintained until a signal is received from said primary video terminal to unlock the conference.

18. The network of claim 7 wherein said switch means comprises:

cross point switch means for receiving video and audio information from each of said network ports having one of said video terminals associated therewith and operable to provide access of each of the audio and video signals to each of the remaining of the associated network ports;

video multiplex means associated with each of said network ports associated with said switch means and operable to receive all of the video output signals from said interconnect means for selective output of only one of the received video signals; and

audio multiplex means associated with each of the network ports associated with said switch means and operable to receive all the audio signals output by said interconnect means for summation thereof and output to the associated one of said network ports, said audio multiplex means inhibiting reception and summation of the audio received from the associated one of said network ports;

said audio multiplex means, video multiplex means and said interconnect means controlled by said slave means.

19. The network of claim 7 wherein said data manager means comprises:

first buffer means for receiving data from each of said network ports and storing the received data in one of a plurality of buffers, each associated with one of said network ports for storage of received data;

second buffer means having a plurality of buffers, each associated with one of said network ports for storage of data for transmission to the associated one of said network ports;

said first and second buffer means effecting data communications with the associated one of said network ports for reception of data from or transmission of data to either said video terminals, said network master means or said slave means, said network master means, said slave means and said video terminals operating asynchronously with respect to each other and said data manager means;

memory means for storing a status table having stored therein the status of all of said network ports, the status determining which of said video terminals, said network master means or said slave means is attached thereto; and

central processing means for strobing the buffers in said first buffer means and retriving received data therefrom, the destination of the received data determined by said central processing means and routed to the one of said buffers in said second buffer means for transmission of data therefrom.

20. The network of claim 19 wherein all data received by said data manager means has destination information encoded therein indicitive of the one of said network ports that it is directed towards.

21. The network of claim 19 wherein all of said video terminals, said network master means and said slave means have a predetermined unique identifying code associated therewith and all of the data received by said data manager means has the unique identifier encoded therein, said central processing means associating the unique identifier with information in said status tables such that the received data can be routed to the one of said network ports that the one of said video terminals, said network master means or said slave means having the corresponding unique identifier is associated therewith.

22. The network of claim 19 wherein said slave means is operable to communicate with each of said network ports associated with said data manager means to determine the status thereof and update said status table in said memory means associated with said data manager means.

23. The network of claim 22 wherein said network master means further comprises network master memory means for storage of network status tables indicitive of the status of all of said video terminals associated with said network ports, said network master means updating said network master table with information stored in said data manager status tables to data communication with said slave means, said slave means effecting a transfer of data from said data manager status tables to said network master means for storage in said network master memory.

24. The network of claim 7 and further comprising data manager memory means for storing status tables having information stored therein regarding the status of all of said network ports, said data manager means operable to access said data manager memory means after identifying the destination to which received data is to be routed such that received data can be routed to the correct one of said network ports.

25. The network of claim 24 wherein each of said video terminals has a unique identifier associated therewith and said network master means has a unique identifier associated therewith, said unique identifiers for said video terminals and said network master means stored in said data manager memory means and associated with the one of said network ports that they are attached to.

26. The network of claim 24 wherein said slave means is operable to communicate with each of the devices on said network ports to determine the status thereof, said slave means updating said data manager memory means with status information obtained thereby.

27. The network of claim 26 and further comprising network master memory means for storing said predetermined interconnect pattern and network status information, said network master means communicating with said slave means through said data manager means to retrieve status information from said data manager memory means to update said network master memory means, said slave means accessing said data manager memory means in response to commands from said network master means to transfer status information to said network master means for storage in said network master memory means.

28. The network of claim 7 wherein each of said video terminals further comprises means for initiating a conference with another of said video terminals in the network, said accessing means operable to generate a message directed to said network master means requesting a conference with a predetermined one of the remaining of said video terminals in the network, said network master means effecting a conference in response to a request from one of said video terminals.

29. The network of claim 28 wherein said network master means further comprises means for generating a message directed toward the one of said video terminals to be placed in conference with the accessing one of said video terminals, said video terminals further comprising means for responding to a request from said network master means to be placed in a conference with the accessing one of said video terminals such that the said network master means is a apprised of the status of the requested one of said video terminals, said network master means communicating with said slave means after receiving said response from the requested one of said video terminals to reconfigure said switch means to provide an audio and video path from the requesting one of said video terminals to the requested one of said video terminals.

30. The network of claim 29 wherein each of said video terminals comprises means for selectively inputting or outputting audio and video information to the data link effected by said network master means.

31. The network of claim 29 wherein each of said video terminals further comprises means for outputting an audible signal on the audio path effected by said network master means when said video terminal is the requested one of said video terminals such that the requesting one of said video terminals can receive an audio feedback indicitive of a completed audio path.

32. The network of claim 31 and further comprising means for outputting an audible signal to the user at the requested one of said video terminals to indicate that an audio and video path has been provided to a requesting one of said video terminals in the network such that the user of the requested one of said video terminals is apprised of the request.

33. The network of claim 29 wherein each of said video terminals further comprises means for accessing the video transmitted from the requesting one of said video terminals prior to transmitting video therefrom such that the user is allowed to preview the video from the requesting one of said video terminals prior to transmitting video thereto.

34. The network of claim 7 wherein said network master means further comprises means for controlling each of said video terminals to enter a hold mode, said video terminals in the hold mode looping back the transmitted video therefrom for reception thereof such that the user of said video terminal in the hold mold receives there transmitted vided.

35. The network of claim 34 wherein the loop back video is looped back internal to said video terminal in the hold mold such that it is not transmitted to the said switch means for processing thereby.

36. The network of claim 7 wherein said communication link means comprises:

a transmission medium associated with each of said network ports for carrying audio, video and data between said switch means, said data manager means and said network port;

first interface means disposed at said network ports for interfacing between the devices attached to said network ports between said transmission medium; and

second interface means disposed at the other end of said transmission medium for interfacing between said transmission medium and said data manager means and said slave means;

said first interface means receiving audio, video and data from the device associated with said network port and encoding it for transmission along a first path in said transmission medium, said first interface means receiving and decoding from a second path in said transmission medium encoded audio, video and data for transmission to the associated one of said network ports; and

said second interface means receiving and decoding encoded data from said first path in said transmission medium for transmission of said decoded audio and video to said switch means and said decoded data to said data manager means, said second interface means receiving data from said data manager means and audio and video from said switch means and encoding the received audio, video and data for encoding thereof and transmission on said second path in said transmission medium;

said first and second paths in said transmission medium isolated to allow full duplex communication.

37. The network of claim 36 wherein said transmission medium comprises a coaxial cable and said first and second interface means encode audio, video and data through frequency division multiplexing techniques.

38. The network of claim 36, wherein said transmission medium further comprises:

a third path isolated from said first and second path for carrying information therealong;

said first interface means interfacing with said third path and with a peripheral network device, said peripheral device operating independent of the video conferencing network; and

said second interface means interfacing with said third path and with a peripheral network, said peripheral network operating independent of the video conferencing network such that said peripheral network device and said peripheral network utilize said transmission medium and operate in parallel with the video conferencing network and independent therefrom.

39. The network of claim 36 wherein transmission of data along said first and second paths in said transmission medium is asynchronous such that said data manager means and the device attached to said network ports communicate asynchronously.

40. The network of claim 7 wherein said communication link means comprises:

a first transmission medium disposed between said network port and said switch means and having a first path and a second path, said first path for carrying audio and video from said network port to said switch means and said second path for carrying audio and video from said switch means to said network port;

first audio/video interface means for encoding audio and video from said network port for transmission along said first path and receiving encoded audio and video from said second path for decoding thereof at said network port;

second audio/video interface means for receiving encoded audio and video from said first path for decoding and routing to said switch means and for receiving audio and video from said switch means for encoding thereof and transmission along said second path;

a second transmission medium disposed between said data manager means and said network port for data transmission;

first data interface means for interfacing data communications between said network port and said second transmission medium; and

second data interface means for interfacing between said second transmission medium and said data manager means.

41. The network of claim 40 wherein said second transmission medium provides a first and second path for data transmission, said first path transmitting data from said network port to said data manager means and said second path transmitting data from said data manager means to said network port such that a full duplex data path is provided.

42. The network of claim 40 wherein said second transmission medium comprises a local area network.

43. The network of claim 40 wherein said first transmission medium is comprised of a broadband multichannel communication link for transmission of encoded audio and video and said first and second audio/video interface means comprise audio/video modems for modulating and demodulating audio and video onto a particular one of the channels in said broadband link, each of said audio and video modems selecting one channel for transmission of encoded audio and video and one channel for reception of audio and video.

44. The network of claim 43 wherein said audio/video modems are operable to transmit or receive audio and video from any of the channels in said broadband link, said audio/video modems controlled by said network master means to determine the channel over which audio and video is to be transmitted or received from.

45. The network of claim 7 wherein said communication link means associated with said network master means carries data only and is comprised of:

a transmission medium for transmitting data;

first data interface means disposed between said transmission medium and said data manager means for interfacing data communications therebetween; and

second data interface means connected between said network master means and said transmission medium for interfacing data communications therebetween.

46. The network of claim 45 wherein said transmission medium comprises a local area network.

47. The network of claim 7 and further comprising:

data manager memory means for storing status information for all of said network ports, said data manager means accessing said data manager memory means to determine which of said ports correspond to the identification information in the received data, the received data routed to the corresponding one of said network ports;

said slave means communicating with said network ports to determine status thereof from response information received from said video terminals or said network master means attached to said network ports, said slave means operable to update the status of said data manager memory means; and

network manager memory means for storage of network status information, said network master means communicating with said slave means through said data manager means to control said slave means to access said data manager memory means to transfer data therefrom for storage in said network master memory means to update the status contained therein.

48. The network of claim 47 wherein:

said data manager means comprises a plurality of secondary data manager means, each of said secondary data manager means associated with a predetermined number of said network ports for receiving data therefrom and transmitting data thereto, each of said data manager means interfaced with the one of said network ports associated with said network manager means; and

said data manager memory means comprise a plurality of secondary memory means each associated with one of said secondary data memory means for storing status information for only the ones of said network ports as interfaced with the associated one of said secondary data manager means.

49. The network of claim 48 wherein said slave means is comprised of a plurality of secondary slave means each associated with one of said secondary data manager means and the associated one of said secondary memory means;

and

said switch means comprises a plurality of secondary switch means each associated with one of said secondary data manager means and for receiving audio and video from each of said network ports interfaced with the associated one of said secondary data manager means and interconnecting the received audio and video for transmission to select ones of said network ports in accordance with said predetermined interconnect pattern, each of said secondary switch means interfaced with each of the remaining ones thereof for transfer of audio and video information therebetween;

said secondary slave means controlling the configuration of the associated ones of said secondary switch means.

50. The network of claim 48 wherein said network master means comprises a plurality of secondary network master means, each associated with one of the associated network ports of said secondary data manager means;

said secondary network master means having a predetermined priority such that only one of said secondary network master means is operable at any given time; and

means for activating the next sequential one of said secondary network master means in the priority scheme when the highest priority one of said secondary network master means is removed from the network.

51. A method for effecting a video conference between remote network ports, comprising:

disposing a video terminal at each of the remote points, each of the video terminals generating output audio and video and receiving input audio and video information, each of the video terminals transmitting receiving data;

interconnecting the audio and video inputs and outputs of select ones of the video terminals in accordance with a predetermined interconnect pattern;

receiving data from the network ports at a central routing device, identifying destination of the data and routing the data to the corresponding destination;

controlling the interconnection of video terminals from one of the ports by establishing data communication therewith, data generated at the controlling point routed through the central routing device to the destination port and data received from the routing device having the controlling port as its destination, the predetermined interconnect pattern generated at the controlling device; and

controlling the interconnection of the audio and video inputs and outputs of the select ones of the video terminals at a slave port by receiving the interconnect pattern at this slave port from the controlling port through the routing device.

52. The method of claim 51 wherein the step of generating the output audio and video signal comprises sensing an image and converting the image to a video signal and receiving audio information from a transmission medium associated with each of the terminals and converting it to an audio signal in the step of receiving audio and video information comprises receiving the video signal and converting it to an image for display and receiving the audio signal and converting it to sound information for transmission through the associated transmission medium.

53. The method of claim 51 and further comprising selectively inhibiting transmission of video from a select one of the video terminals while receiving video from another of the video terminals that is selectively interconnected therewith.

54. The method of claim 51 wherein data communication between the controlling port and video terminals and the slave port is asynchronous.

55. The method of claim 51 wherein the interconnection of video terminals is controlled to place select ones of the video terminals in a conference with all of the video of each of the video terminals received at a central switching point and only one video transmitted from the central switching point to each of the video terminals in accordance with a predetermined priority pattern generated at the controlling port and receiving audio from each of the video terminals at the central switching point that are in the conference and summing the received audio for each of the video terminals in the conference for transmission thereto with the exception of the video generated by the receiving one of the video terminals such that each of the video terminals in the conference receives only summed audio from the other video terminals in the conference.

56. The method of claim 55 wherein the priority pattern generated at the controlling designates one of the video terminals in the conference as a primary video terminal with the video from the primary video terminal received by the remaining of the video terminals in the conference and one of the video terminals in the conference as a secondary video terminal with the video from the secondary video terminal received by the primary video terminal, the remaining of the video terminals in the conference designated as m-ary video terminals, the priority pattern generated only when three or more of the video terminals are in a conference, each of the video terminals operable to transmit a request to the controlling port to become the primary video terminal such that the controlling port updates the priority status of the requesting one of the video terminals to primary and degrades the status of the prior primary video terminal to the secondary video terminal and the prior secondary video terminal to one of the m-ary video terminals.

57. The method of claim 56 and further comprising generating a request for primary status at each of the video terminals in response to receiving voice information that exceeds a predetermined threshold from the user of the video terminal, the voice signal exceeding the predetermined threshold for a predetermined amount of time.

58. The method of claim 56 and further comprising generating a conference lock signal at one of the video terminals for transmission through the central routing device to the controlling port, the controlling port inhibiting alteration of the priority pattern upon receipt of the conference lock signal such that the video terminal generating the conference lock signal has the status thereof updated to the primary video terminal, the status maintained until the signal is received from the primary video terminal to unlock the conference.

59. The method of claim 51 the step of receiving and routing the data at the central routing device comprises:

receiving the data from each of the network ports and storing it in one of the plurality of buffers, each buffer associated with one of the network ports for storage of received data;

identifying the port to which the data stored in the received buffers is to be routed;

routing the identified data to one of a plurality of output buffers, each buffer associated with one of the network ports for storage of output data for transmission thereto;

step of receiving data for storage in the receiving buffers and the step of transmitting data from the output buffers effected by asynchronous communication between the network ports;

storing a status table having stored therein the status of all of the network ports, the status determining whether the network port associated with the video terminal, a controlling port or a slave port;

the step of determining the destination from the received data determined in accordance with the information stored in the status table.

60. The method of claim 59 wherein the data received and stored in the received buffer has destination information encoded therein indicitave of one of the network ports that it is directed towards.

61. The method of claim 59 wherein all the video terminals, the controlling port and the slave port have a predetermined unique identifying code associated therewith and all the data received at the central routing point has a unique identifier encoded therein, the unique identifier decoded from the data and associated with information in the status table such that the received data can be routed to the appropriate one of the network ports having the unique identifier associated therewith.

62. The network of claim 59 and further comprising storing network status tables at the controlling port indicitive of the status of all of the video terminals associated with network ports, the controlling port updating the network status tables with information stored in the data routing status tables without a controlling port to control the network from information stored in network status tables.

63. The network of claim 51 and further comprising:

initiating a conference at each of the video terminals by generating requests data for the controlling port and transmitting the request data thereto, the controlling port operable to generate a request message and direct it to the destination port to request access thereto, the video terminal at the network port receiving the request data generating response data and transmitting it to the control port to indicate status thereof, the control input operable to interconnect the access requesting video terminal and the requested video terminal if the response of the requested video terminal is appropriate in accordance with a predetermined protocol.

64. The method of claim 63 and further comprising generating an audible ring back signal at the requested video terminal prior to receiving audio or video from the interconnection effected by the controlling port such that the requesting video terminal is provided audio feed back.

65. The method of claim 64 and further comprising generating an audible signal at the requested one of the video terminals in response to the controlling port effecting an audio and video communication path to the requesting one of the video terminals such that the user is apprised of the interconnection, audio and video transmission from the requested video terminal inhibited from being transmitted over the audio and video interconnection.