Abstract:
An effective communications system for assuring compatibility between new and existing networking technologies is described which may be utilized to prevent the use of trial and error techniques in the establishing of the best possible connection between a calling terminal or modem and a destination terminal or modem. An enhanced services platform is provided which establishes the connection based on the signaling capabilities of both the calling and destination terminal, provides for in-call modification, and provides for call teardown.

Description:
This application claims priority to and the benefit of the filing date of U.S. provisional application entitled “A Signaling Capable Telecommunication System and Method,” filed Jun. 11, 1997, and accorded Ser. No. 60/049,318. 
    
    
     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&#39;s memory. Based upon the calling modem, or terminal&#39;s signaling capability and type, and the called modem&#39;s or called terminal&#39;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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and benefits of the invention will be more clearly understood with reference to the specification and the accompanying drawings in which: 
     FIG. 1 is a block diagram of applications that may connect through a network to an ESP; 
     FIG. 2 is an illustrative diagram showing the major component interconnections in a system for implementing the present invention; 
     FIGS. 3A and 3B are flowcharts illustrating call establishment in the preferred embodiment of the present invention; 
     FIG. 4 is a flowchart illustrating in-call modification in the preferred embodiment of the present invention; and 
     FIG. 5 is a flowchart illustrating call teardown in the preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a high level, block diagram illustrating a possible architecture of a signaling capable telecommunication system according to the present invention. The telecommunication system comprises an enhanced service provider (ESP)  22  terminating a plurality of customer terminals. In the preferred embodiment, ESP  22  is capable of terminating customer terminals over a variety of communication links and protocols. For example, terminals may access the ESP via a non-signaling capable modem  10 , a signaling capable modem  12 , a link running TCP/IP  14 , a basic rate ISDN (BRI) line  16 , a digital subscriber line service (xDSL; hybrid rate, symmetric, asymmetric, etc.)  18 , or a traditional telephone  20 . FIG. 2 illustrates the components of ESP  22  in greater detail. 
     As shown in FIG. 2, ESP  22  includes a processor  30  in communication with a memory device  32  via a local interface. Memory device  32  holds the software program and data for the signaling capable telecommunication system  34 . In addition, processor  30  has access to a plurality of communications interface devices  38  that terminate the customer terminals discussed hereinbefore in reference to FIG.  1 . The hardware and software architecture of communications interface  38  will vary depending on the type of line and/or protocol being terminated. In the example shown, separate communications interface modules  38  are used to terminate terminals accessing ESP  22  over an ISDN  40 , a public switched data network (PSDN)  42 , a PSTN  44  or via an Internet protocol based network (IP)  46 . 
     Operation of the preferred embodiment is described hereafter. Referring to FIG. 1, a non-signaling modem  10  calls an ESP  22  through a network that supports the non-signaling modem. Other terminals are also supported by the ESP  22  by connecting through networks which support the terminals. Examples of such terminals are a modem capable of signaling  12 , a device which utilizes a transmission control protocol/internet protocol (TCP/IP)  14 , a device using a BRI  16 , a device using xDSL  18 , or a telephone  20 . 
     Referring to FIG. 2, the ESP  22  according to the present invention is illustrated. In the preferred embodiment, the ESP stores default entries in a table  36  located in memory  32  containing a software program and data for the signaling capable telecommunications system  34 . These default entries may be programmed by a user to show the capabilities of telephones  20 , standard modems  10 , or any other telecommunication mechanism that may have standard operational values. In this illustration a standard modem is a modem without signaling capability. 
     After an ESP customer makes a call to the ESP  22 , a processor  30  reads the maximum bandwidth and application capability of each terminal, whether the application be voice, data, video, image, or another application, through a communications interface  38  and stores the maximum communication capabilities in the table  36 . As is shown in FIG. 2, different communication interfaces  38  may be utilized for different networks such as a PSDN  40 , an IP based network  44 , a PSTN  42 , or an ISDN. 
     Referring to FIG. 3A, a flow diagram representing call establishment according to the preferred embodiment of the current signaling capable telecommunication system is shown. A call is made by a terminal to the designated ESP  22  through a network. Once the call is received the ESP  22  recognizes the bearer capability of the requested call  50 . The bearer capability describes the communication capability of the channel being used to call the ESP  22 . Thus, if a channel is being established for a voice transmission, the bearer capability is a voice channel. Similarly, if a channel is being established for a video transmission, the bearer capability is a video channel. The ESP  22  then compares the bearer capability of the requested call  50  to the default values in the table  36  (FIG.  2 ), thereby checking for deviation. In the preferred embodiment, the default values in the table  36  (FIG. 2) are the default values for a voiceband modem, which is a normal, non-signaling modem, or a telephone  20 . The ESP  22  then checks whether the calling terminal is a voiceband modem  52 . When the calling terminal is a voiceband modem the ESP  22  recognizes the bearer capability of the requested call. The calling modem is then checked for signaling capability  58 . If such capability is present, the modem establishes an out-of-band signaling channel  62  which provides for the continuous supervision of the connection, during the life of the connection. Alternate embodiments may implement the out-of-band signaling channel as a Virtual Circuit or a sub-channel using time division multiplexing (TDM). After establishment of the out-of-band signaling channel  62  the modem or terminal requests connections for the applications relevant to the modem or terminal call  66 . These applications are directly related to the type of modem or terminal that is being used, an example being a fax transmission for a fax modem. Finally, the modem or terminal requests connections, via the out-of-band signaling channel, to the destination terminal(s) for a set of services  64 . In the preferred embodiment the set of services pertain to the specific parameters needed to perform an application at the highest quality level. 
     When the calling modem does not have signaling capability a normal mode handshake is applied between the ESP  22  and terminal or modem  60 . This modem or terminal could support voice, data, video or any of numerous communication means. 
     The ESP  22  then calls a destination terminal or modem using a numbering plan  68  such as E.163 or E.164. Completion of this call leads to further establishment of the requested call based upon the called terminal&#39;s capabilities as is further discussed in the detailed description of FIG.  3 B. 
     If, as previously checked, the calling terminal is not a voiceband modem, the calling terminal is tested for the presence of a D-channel  54 . Where a D-channel exists the modem or terminal requests connections for the applications that are to be implemented by the terminal  66 . The terminal then requests connections to destination terminal(s) for the set of services on the signaling channel  64 . If, however, the calling terminal does not have a D-channel, a normal mode handshake is applied between the ESP  22  and the calling terminal or modem  60 . Once again, the calling modem or terminal could support voice, data, video or any of numerous combinations of these or other applications. The ESP  22  then calls a destination terminal or modem using a numbering plan  68  such as E.163 or E.164. Further steps for completion of the established call are discussed in the detailed description of FIG.  3 B. 
     Referring to FIG. 3B, a flow diagram representing call establishment according to the preferred embodiment of the current signaling capable telecommunication system and continuing from FIG. 3A, is shown. The ESP  22  then checks the destination terminal for D-channel signaling capability  70 . If the destination terminal has D-channel signaling capability the ESP  22  exchanges the previously stored maximum capabilities from the table  36  (FIG. 2) in the memory  32  (FIG. 2) of the signaling capable telecommunications system, with the capabilities of the destination terminal to establish a best/closest bearer  84 . In the preferred embodiment the standard used to control the signaling is Q.931. The Q.931 standard defines a protocol that performs such services as routing of chosen numbers and knowledge of whether the destination is not reached or the called line is busy. The ISDN recommendation Q.931 is implemented as a server that is reached through a socket interface. This makes it possible to connect to the ISDN server from any host over a data network, such as TCP/IP network. 
     At this point a call has not been established; only a D-channel check has been performed, and that does not necessarily require that the call be established. If, however the destination terminal does not have D-channel signaling capability, the ESP calls the destination terminal  80  and checks for signaling capability  82 . If the modem is signaling capable, the terminal establishes an out-of-band signaling channel  88 . The ESP and destination terminal then exchange capabilities and establish the bearer at the best/closest rate  84 . If, however, the destination terminal does not have signaling capability a normal mode handshake is used  86  between the destination modem and ESP  22 . After a normal mode handshake is established for the non-signaling capable modem  86  the ESP and destination terminal exchange capabilities and establish the best/closest bearer capability  84 . A further check is made by the ESP  22  as to whether the closest bearer capability is null  90 , or has been disconnected. If the closest bearer capability is null the call is terminated  94 . Otherwise, the ESP, calling modem and the destination modem communicate through the previously established channel  92 . 
     Referring now to FIG. 4, after a call has been established through the previously established channel, as has been discussed in the aforementioned detailed descriptions of FIGS. 3A and 3B, in-call modification is provided for. In the illustrative embodiment, in-call modification is permitted for any signaling capable terminal  100  (SCT), an example being a modem capable of signaling. The terminal requests to add or drop a specific application activation  102 , which was previously activated during call establishment  66  (FIG.  3 A). Examples of when this sequence would be necessary would be when a request is made to fax a document while on a conference call or when a user changes a normal telephone call to a conference call, in which the capacity of the channel being used must be expanded. The ESP  22  notifies the SCT of the change request  104  by the terminal, at which point the SCT acknowledges the ESP  106 . The ESP  22  then reconfigures the table  110  in memory  32  (FIG.  2 ). Finally, the ESP  22  sets-up or deactivates the newly requested applications  112  from the terminal. 
     In reference to FIG. 5, a call teardown option is provided so each terminal may request to teardown the previously established call. Call teardown is achieved by the ESP  22  after a request has been received from a terminal  120 . Call teardown, such as the loss of a carrier, can also be recognized by the ESP  22 , at which point the ESP will de-establish the corresponding connection. After teardown the ESP  22  reconfigures the application table  124 . By this process, if the lowest common denominator between applications is removed, the application table will adjust the remaining applications accordingly to show a higher, lowest common denominator between the running applications. After adjustment, the ESP  22  notifies the other links of the dropped party  126 . Finally, if only one terminal remains, the ESP  22  (FIG. 1) clears all calls from the table  128 . 
     Although the illustrative embodiment described hereinabove implements a virtual circuit to establish the out-of-band signaling channel, one of ordinary skill in the art will appreciate that other circuits having similar signaling capabilities such as dedicated time division multiplexed bandwidth, may be substituted. 
     Although the invention has been shown and described with respect to exemplary embodiments thereof, various other changes, omissions and additions in form and detail thereof may be made therein without departing from the spirit and scope of the invention.