Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1997-10-17
2001-01-16
Vu, Huy D. (Department: 2733)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
Reexamination Certificate
active
06175576
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to communications systems using modems, and more specifically, to signaling capable modems and telecommunication systems that promote compatibility in new and existing networking technologies.
2. Description of Related Art
With advancements in communications technology, multimedia and telecommunication services have become more prevalent in our industry. The emergence of multimedia in the marketplace, coupled with the adoption and increasing implementation of new networking technologies such as integrated services digital network (ISDN), frame relay (FR) network, broadband ISDN and the Internet has brought to the attention of network designers certain practical communication compatibility issues associated with the integration and coexistence of these new networks with the standard ‘telephony’ network, also known as plain old telephone service (POTS) or public switched telephone network (PSTN). Furthermore, the advances in voiceband modem, or standard non-signaling modem, technology has made their capability suitable for many multimedia applications.
Modem technology also benefits when a universal service is available that has made its use ubiquitous and easy. The implementation of a universal service allows for the advancement of such technology at a faster rate. Therefore, there is a need for interworking between the new (e.g., ISDN, FR, the Internet) and the existing (e.g., voiceband modems, POTS) networking technologies.
One major compatibility issue relates to the diverse types of calls that a caller using multimedia terminal devices can initiate to a called party whose subscriber line characteristics and terminal device media support capabilities are unknown. For example, when a caller using an ISDN compliant multimedia service wants to communicate with a called party whose access line arrangement and terminal device media support capabilities are unknown, the caller can start a call based on the lowest common denominator capability and after the connection, establish the higher available capabilities, acquiring a higher capacity channel. Such requirements from the terminal devices can often be too demanding, since the terminals need to have a number of standard technological capabilities. This problem is exacerbated as the number of communication standards grows. On the other hand, if the call is initiated using a higher capability by the calling terminal than can be recognized by the called terminal, the called terminal may not be able to respond and establish an intelligible communication link. This turn of events leads to a loss of time in the user utilizing trial and error techniques until call establishment is acknowledged by the called terminal, if acknowledged at all.
In addition to the above-mentioned concerns with call initiations, other concerns exist for call modification. During a call, sometimes it is necessary to modify the nature of the connection or application that is using the connection, such as when a user changes a normal telephone call to a conference call in which the capacity of the channel being used must be expanded. This problem has been addressed in the ISDN environment, which implements signaling to tell when modification is necessary. Unfortunately, current PSTN modem equipment is unable to implement this capability.
SUMMARY OF THE INVENTION
The present invention provides an effective communication system for assuring compatibility between new and existing networking technologies, thereby providing a universal service and alleviating trial and error techniques.
According to the invention, a signaling capable modem is first defined. The signaling capability uses an out-of-band signaling channel and a Q.931 message set in a manner similar to ISDN terminals. This signaling channel could be implemented as a virtual circuit (VC) or a sub-channel using time division multiplexing (TDM). The invention also includes an inter-working/conferencing platform, which in the preferred embodiment is implemented by software and which is referred to as an enhanced services platform (ASP). The ESP enables interoperability between called and calling terminals. This interoperability exists among these modems as well as with other signaling capable devices and terminals (voice, data, video, image, etc.).
In accordance with the invention, all terminals start their call setup procedure by calling the ESP which has a designated number. The ESP then performs a series of tests and comparisons between the called terminal and previously stored, default values located in the ESP's memory. Based upon the calling modem, or terminal's signaling capability and type, and the called modem's or called terminal's signaling capabilities, the ESP establishes the best possible connection between the modem or terminal requesting the call and the modem or terminal receiving the call.
The ESP also provides for the testing of whether the closest bearer capability between the calling terminal and the receiving terminal is null, or disconnected, upon which detection of disconnection will provide for the termination of the call and a lack of disconnection will provide completion of the call.
To accomplish the above tasks, the ESP should have the following functional capabilities and features. The ESP should know the bandwidth and application capability of each terminal, whether that terminal supports voice, data, video, image, or some other means for communication. This is done by the ESP setting up a table in memory after negotiating and interrogating the capabilities and requests of each terminal. The ESP should identify the communication application based on a table for some terminals. Default entries for telephones and standard modems may also be stored in the table located in memory.
Each terminal can also request to teardown the call whereby the ESP will perform the teardown. The ESP can also recognize circuit teardown, an example being the loss of a carrier, and then de-establish a connection. After is call teardown, the ESP reconfigures the application table since the highest common denominator might have changed to a higher level or the lowest common denominator might not exist anymore. The ESP then notifies other links of the dropped party. Finally, if there is only one terminal connected to the ESP, the ESP clears all calls and the call table.
The ESP also provides for in-call modification of any previously established call to a destination terminal via the ESP. Such a modification would be characteristic of a change in the needed capacity of an established connection to a destination terminal due to the nature of the newly requested application, an example being a request to establish a conference call while on a normal telephone call.
Features of the invention include a dependable solution to a lack of compatibility between new and existing networking technologies. Maximum support capability is made available without the use of trial and error techniques. Active modification of channel capacity is provided to allow for multiple tasks simultaneously and the changing of functions without a need for the opening of a new channel, or re-dialing, for different channel capacities. The invention also allows for multiple connections to single or multiple destinations. This allows for the best available communication quality based on a lowest common denominator.
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Boakye Kwame
Mohammadi Khashayar
Kwoh Jasper
Paradyne Corporation
Vu Huy D.
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