Automatic ISDN switch

Details Automatic ISDN switch Automatic ISDN switch

1999-08-23

2002-10-15

Kuntz, Curtis (Department: 2643)

Television

Two-way video and voice communication

User positioning

C379S202010, C370S260000, C370S261000

Reexamination Certificate

active

06466251

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to switching of communication signals, e.g., integrated services digital network (“ISDN”) signals. A preferred embodiment of the present invention is an automatic ISDN switch that automatically detects the presence of an ISDN device at one of a plurality of locations and automatically routes all audio, video, and data to that one location while locking out all of the other locations connected to the switch. The ISDN switch of the present invention has numerous applications, including by way of example videoconferencing using a 128 kbps (128,000 bits per second), 256 kbps, 384 kbps, or 512 kbps ISDN configuration.
BACKGROUND OF THE INVENTION
Videoconferencing has recently undergone an evolution. Prior to this evolution, videoconferencing equipment was typically semi-permanently installed in a dedicated location with dedicated, permanently installed communication lines. The recent evolution took the form of making videoconferencing equipment mobile. In the past few years, most videoconferencing equipment on the market has been marketed as being mobile and by far the majority of videoconferencing systems sold over the past few years have been mobile systems.
There are a number of standard communications methodologies that can be used in videoconferencing. Currently, the most widely used videoconferencing communications medium in the United States and internationally is ISDN, which is the basis for a number of different specific communications configurations. One ISDN videoconferencing communications family of standards is known as H.320 (ITU-T) promulgated by the International Telecommunications Union (formerly known as CCITT). One implementation allows 384 kbps transmission of information using three individual ISDN-BRI (Integrated Services Digital Network-Basic Rate Interface) telephone lines. This form of videoconference transmission is also known or described as “six-channel transmission” in the videoconference industry, because it uses six ISDN channels, each of which carry 64 kbps of digital information. Each ISDN-BRI telephone line includes two separate 64 kbps lines or channels, as they are referred to in the videoconferencing industry. The H.320 standard encompasses video (e.g., videoconferencing), audio, and control using one or more 64 kbps ISDN lines. A majority of corporate videoconferencing installations currently use six 64 kbps ISDN lines, using three two-channel ISDN-BRI lines; while other applications such as medical videoconferencing applications use as many as eight 64 kbps ISDN lines.
One obvious benefit of using mobile ISDN videoconferencing equipment is that one videoconferencing unit can be used at a number of locations in the same facility. However, connecting ISDN devices to an ISDN line is complicated by the fact that ISDN lines must be properly terminated with an industry standard network U-interface, such as an NT-1, an NT-3, or a Triple NT-1. Only a single device (more specifically a U-interface) may be connected to a BRI line. Businesses requiring use of ISDN lines in more than one location have had two acceptable prior art options: (i) installing multiple data lines for each possible location or (ii) installing a patch panel at the point of termination with which one can physically manipulate the termination point of the ISDN line(s). A third prior art option, daisy-chaining, is not an acceptable option because it has problems of signal quality consistency, security, and accessibility, as will be discussed below.
The first prior art option, installing multiple data lines for each possible location, is very costly and inconvenient. One implementing the first prior art option would be charged for the installation of each set of three ISDN lines (recall that with the majority of corporate or industrial videoconferencing installations—as compared to typical home usage—each location requires access to three two-channel BRI telephone lines), the digital monthly services charges for each set of three ISDN lines for each location, even when lines are not used, and the cost of the (3) CAT-5 wires to each location beyond the initial point of termination. Thus, to implement this first option using current wiring standards, it is necessary to run multiple data lines from the point of presence (the phone room in typical installations) to each possible destination. If, for example, a 384 kbps ISDN configuration were to be needed in 3 different rooms, it would be necessary for a total of 9 data lines be run (3 ISDN 2 channel lines from point of presence to destination). The cost and type of cabling must be considered for such an implementation; expensive CAT-5 or CAT-6 wiring is specified. The cost of this option can become prohibitive with only a few locations. Moreover, under these stringent installation methods, flexibility of conference locations is not an option due to the fact that the wiring must be permanently installed.
Additionally, the first prior art option is inconvenient to use with a mobile videoconferencing unit. As known to those in the art, each videoconferencing system has an ISDN network interface (e.g., an NT-1, an NT-3 or an Triple NT-1) that acts to terminate the ISDN line(s) used in that system and an ISDN video codec. Each 64 kbps ISDN line has its own unique telephone number. As also known to those in the art, the ISDN video codec must be programmed with the telephone number(s) for each ISDN line(s) used. Thus, moving a mobile videoconferencing unit from one location to another requires that six telephone numbers be programmed into the ISDN video codec, which typically must be done by busy MIS personnel. At least one ISDN video codec in the art, i.e., a unit from Polycom Inc., includes software that attempts to automatically detect the phone numbers associated with the ISDN lines and program those numbers into the video codec. However, this autodetection process can take 5-10 minutes and is not always successful; the system might fail to detect the telephone numbers. Also, executing the autodetection process still typically requires MIS personnel to perform.
The second prior art option is to install a patch panel in the telephone closet or another location with which one can physically manipulate the termination point of the ISDN line(s). This option has a great deal more flexibility than the first option, in that one can wire multiple rooms for access and simply ‘patch’ the data lines to the destination at the time of need; however, it suffers from relatively high cost and is inconvenient as well.
More specifically, the second option requires that all communication lines be brought to the point of presence and terminated in a patch bay. Located near the incoming patch bay, typically underneath, is a patch panel. Simply put, the electrical connection between the patch bay and the patch panel resembles the old switchboard banks that telephone operators would use to directly electrically connect a caller to a destination. The same antiquated manual process used to route telephone calls, before and during the 1950's is currently used to route ISDN lines with the patch panel. Because ISDN technology requires termination at each end to properly operate, the patch panel routes the ISDN lines to a single termination point and isolates all other signal access locations. The patch panel has the benefit of giving the user security, in that the data lines can only be connected to a single destination; therefore, eavesdropping through another room is not possible. Another advantage of the patch bay over the first prior art option is that there is flexibility in provisioning data lines; more data lines can be added without changing the wiring plant. In the alternative, manual switches are used instead of the manual patch panel in this prior art option.
There are difficulties with the patch panel method of connecting ISDN lines as well. One of the primary drawbacks of using a patch panel to route ISDN lines to various destination locations is inconvenience. Switching the ISDN lines f

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