Abstract:
An enhanced computer telephony (CT) network design for a private branch exchange (PBX) telephone system network improves the computer telephony interface (CTI) capabilities of the network. Bi-directional data from remote telephone switching nodes of different PBX systems, each using a common software application, is combined into a single data stream by the network to simplify control of the remote PBX systems. Commands to, and events received from, the different PBX switching nodes are combined by use of a gateway to automatically and transparently route digital information for control of the correct remote system node.

Description:
BACKGROUND  
         [0001]    Customer owned private branch exchange (PBX) systems are in widespread use. PBX systems adequately serve a large number of stations or telephone extensions in a single location. Frequently, however, customers have multiple locations, each having a PBX system or hybrid key system associated with it. These systems typically are controlled by computer-telephone integration (CTI) processors into various types of networks.  
           [0002]    An early communications switching concept was disclosed in U.S. Pat. No. 4,527,012 to allow telephone call processing to be carried out by a host computer connected to a telephone system. The host computer viewed the telephone system as a peripheral device. The host computer then controlled the switching system with a series of high level commands exchanged between the switching system and the host computer. The commands were referenced to physical system ports to control the operation of those ports directly, based on the current call processing state. The connection of the host computer to the telephone system was accomplished by using a serial port (such as the RS-232 port). The system of this patent, however, and systems similar to it, are not inherently capable of connections or control using a computer network like TCP/IP because of the electrical network interface limitations of serial ports. In addition, computer programs of the type disclosed in the &#39;012 patent must be aware of each equipped physical system port, and maintain a separate cross reference to correlate ports functionally to the assigned extension numbers, trunk numbers and so forth.  
           [0003]    A different approach is disclosed in U.S. Pat. No. 4,653,085. In the system of this patent, computer telephony is implemented by attaching an adjunct processor to an associated telephone system port and sending control information for calls requiring additional call processing using a data exchange with the adjunct computer to simulate the actions of a connected station. The system of this patent requires all telephone calls, which are to be handled according to the stored program in the adjunct processor, to be transmitted by the telephone system to the port associated with that adjunct processor. The adjunct processor then sends direct commands back to the telephone system indicating the disposition of the call by directly sending a command to the port being served. Consequently, the adjunct computer simulates the behavior of a human operator. This system is limited by the volume of traffic which can be processed by a single operator (adjunct computer), and therefore it is not suitable for system-wide call handling tasks without terminating multiple ports to simulate the activities of multiple human operators.  
           [0004]    U.S. Pat. No. 5,414,762 is directed to a system for providing computer control to a variety of PBX systems. In the system of this patent, a controller is used to allow one or more computers from a group of computer clients to send commands to a PBX by way of a server computer, and also to receive status information from the connected PBX. A converter which is specific to a particular PBX manufacturer is provided to allow the brand of PBX to be changed without having to modify the communications protocol, and therefore, the application software, that the computer client contains. The primary focus of this system is to allow the same client software to control a variety of PBX platforms. The system of the patent, however, provides no functional support for an application software developer to address the needs of multiple PBX systems, or for expanded networks of PBX systems in multiple locations. In either of these cases, the application software must be enhanced to allow it to be aware of, and to properly control, multiple PBX nodes. Because the application software resides at the client level, it can only control one call per work station and cannot address the needs of the entire system. An approach to resolve problems associated with routing calls to geographically distributed PBX nodes is disclosed in U.S. Pat. Nos. 5,546,452 and 5,848,143. The systems of these patents use a central controller with global authority to allow resident software to route calls appropriately to agents who are connected at various locations within the PBX network. The systems disclosed in these patents require the central processor to be equipped with routing and management software specifically designed for the expected call processing activity. These systems do not facilitate the transposition of a generic computer telephony application from a single PBX to networked PBX environment, and must take full control of the PBX network by correlating the identities of logged-in agents with a physical node and port locations in the PBX. As a consequence, the approach used in the systems of these patents requires a facility which must undergo continuous parallel maintenance to keep up with PBX user changes.  
           [0005]    U.S. Pat. No. 5,479,487 discloses a system for allowing a centrally located scripting language to control a call as it passes between functional partitions within a call center system. The system creates a scripted development environment for distributed call processing products; but it does not address cases where there is a distributed network of PBX systems which require computer telephony control from some centralized application.  
           [0006]    U.S. Pat. No. 6,011,844 is directed to a system for saving long distance toll charges. The system uses interconnected computer gateways to coordinate the switching of calls between network call centers. Each of these call centers receives telephone traffic according to methods designed to provide the lowest cost handling of each call, and only “bridges in” calls over the long distance network when necessary. The system of this patent is narrowly focused on reducing call traffic over the long distance network which may be handled in a local call center. The system is not capable of centralized consolidation of events arriving from different connected PBX nodes.  
           [0007]    With the advent of intelligent networks within the public telephone system, U.S. Pat. No. 6,094,479 is directed to a solution which allows for the public network service control element to link with a PBX located within a customer&#39;s private network by using a gateway between the private and public network segments. The gateway, however, is limited in its functionality because it simply provides a standard means to link between two networks, and does not address the problems created when a customer makes the transition from single to multiple PBX nodes within a private network.  
           [0008]    U.S. Pat. No. 6,181,788 is directed to a system for achieving uniform control of mixed platforms in telephony. Not all PBX manufacturers use the same protocols to implement computer-telephone integration (CTI) interfaces to a control computer. This patent is directed to a solution to solve software interface problems for customers who have a network of mixed types of PBX systems. The solution proposed in the &#39;788 patent is to use the CTI processors to convert the protocols from each PBX and then network together the CTI processors by way of a peer-to-peer network. Each CTI processor contains its own software with some form of messaging used to loosely link the various systems at each site. This patent is directed to the problem of mixed or different PBX system types. The patent does not address the problem of system scaling (that is, adding additional PBX&#39;s to a customer&#39;s system), and control of networked systems using a common software application.  
           [0009]    It is desirable to enhance the CTI functionality of a PBX network having multiple nodes by combining bi-directional data from remote telephone switching nodes (different PBX systems) into one data stream to simplify the control of the remote system.  
         SUMMARY OF THE INVENTION  
         [0010]    It is an object of this invention to provide an improved system and method for serving multiple telephone switches.  
           [0011]    It is another object of this invention to provide an improved method and system for a private branch exchange (PBX) telephone system network.  
           [0012]    It is an additional object of this invention to provide an improved interface network linking a plurality of PBX systems over a wide area network.  
           [0013]    It is a further object of this invention to provide an improved system and method employing computer telephony interface (CT) for a private branch exchange (PBX) telephone system network using a common software application for linking each of the PBX exchanges together in a transparent manner to users at any of the exchanges.  
           [0014]    In accordance with a preferred embodiment of the invention, a computer telephony interface CT) for a private branch exchange (PBX) telephone system network utilizes a gateway processing system located on an adjacent computer. Each of the PBX systems has a unique address; and they are linked together through a wide area network (WAN), local area network (LAN), or the Internet to the Gateway processing system. The processing system includes translation tables for the addresses, as well as individual station extensions; so that calls originating from any one of the PBX systems on the network and directed to a station on any of the other PBX systems on the network pass their event (call progress) notification through the gateway where it is translated and directly sent to all users (applications) that requested the information in a manner which is transparent to the users of the system. Thus, the users are not aware that more than one PBX system is involved in the call event. The system also allows for changing the data in the translation table to allow relocation of a device associated with a particular extension number to any one of the PBX systems in the network without requiring individual programming at that, or any other, network. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a schematic diagram of a preferred embodiment of the invention;  
         [0016]    [0016]FIG. 2 is a flow chart useful in explaining the initialization of the system;  
         [0017]    [0017]FIG. 3 is a flow chart illustrating software application processing;  
         [0018]    [0018]FIG. 4 is a flow chart illustrating an operation of the system shown in FIG. 1; and  
         [0019]    [0019]FIG. 5 is a flow chart illustrating an operation of the system shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0020]    Reference now should be made to the drawings, which illustrate a preferred embodiment of the invention. FIG. 1 is a block diagram illustrating the inclusion of a CT gateway processor as part of the system. As shown in FIG. 1, four separate PBX systems  10 ,  20 ,  30  and  40 , all using a common software application, are employed as part of a PBX network for a single user, such as a business with offices in four different locations. Each of the PBX systems is connected with the public switched telephone network (PSTN), shown as  12  for the PBX  10 , and includes a plurality of telephone devices or locations, shown as  14  for the PBX  10 , each of which are reached by a particular extension number. For the PBX systems  20 ,  30  and  40 , the PSTN links are shown as  22 ,  32  and  42 , respectively; and the telephones associated with the individual PBX&#39;s  20 ,  30  and  40  are indicated as  24 ,  34  and  44 , respectively.  
         [0021]    In the system shown in FIG. 1, all of the different PBX locations are linked through a wide area network (WAN)  50 , through a site router  52 , for communication with one another. For the PBX  10 , the local interconnections to a local area network (LAN)  60  are indicated; and the LAN  60  is shown as utilizing a computer-telephony integration (CTI) applications processor  62  associated with it for executing applications for communicating between the different PBX systems on the network over the WAN  50 .  
         [0022]    Also illustrated in FIG. 1 is a CTI application desktop and telephone  64  connected to the LAN  60 , which can be linked to and through the PBX  10  in a conventional manner. Other system devices with which the computer telephony interface (CT) gateway processor  66  communicates also may be included; and stub-outs showing potential connections to such other devices on the LAN bus  60  are indicated in FIG. 1. It should be noted that communications through the CT gateway  66  to different PBX nodes, such as the remote nodes  20 ,  30  and  40  are effected by using a standard site router device  52  to send and receive TCP/IP packets in data transfers in a conventional manner.  
         [0023]    The operating software of the system control arrangement which is effected by the CT Gateway  66  constantly accesses and updates information from a common translation database as data arrives by way of the WAN  50  or LAN  60  on behalf of each of the switching system notes  10 ,  20 ,  30  and  40 . Each switch node has a respective socket  74  which it uses for communications to the CT Gateway  66 . The Gateway stream process  70  continuously polls these sockets  74  in the event that the switching node has sent data to it. All of this is placed into a resulting consolidated event data stream made available to one or more CT software applications automatically. This is illustrated generally in the circuit of FIG. 1 by the interconnections from the listening or incoming IP sockets  68  to the CT stream gateway processor  70 .  
         [0024]    Although the system described immediately above refers to specific “sockets”, rather than relying on actual physical connections employed by previous product designs, the CT Gateway  66  only requires that a standard TCP/IP network connection be available between the connected devices. This allows a network installer to quickly verify that all required devices are properly interconnected into the network logic without having to interconnect complicated panels of physical RS-232 ports. The end result is an interconnection topology based on standard TCP/IP networks recognized by the computer industry. The application-level information present within the TCP/IP packets acts as a transport for the majority of the communication network infrastructure of the preferred embodiment of the invention illustrated in FIG. 1.  
         [0025]    In order to transparently program and/or control each of the various telephony devices, such as  14 ,  24 ,  34 ,  44 , or “extensions” used with any one of the PBX systems  10 ,  20 ,  30  or  40 , an extension number and node translation data base memory  72  is provided for mapping all of the extensions in all of the PBX systems  10 ,  20 ,  30  and  40  into a single random access memory  72 . Once this is done, the specific extension number, as well as the IP address for the PBX  20 ,  30 ,  40  or  10  with which it is associated, is stored in the memory  72 ; and a link from a calling party at any of the PBX system nodes is made by the CT Gateway processor  70  through corresponding output node “sockets”  74 , equal in number of the number of PBX systems  10 ,  20 ,  30 ,  40  (or whatever number) used in the completed network. Once again, while specific reference is made to “sockets” on the output side of the processor  70 , it should be noted that standard TCP/IP network connections are utilized to effect the transfer of data from the CT Gateway  66  back onto the LAN  60 , and then on through the site router  52  and the WAN  50 , if necessary, to the desired location.  
         [0026]    In order for the Gateway to provide data to applications, the CT Gateway  66  must be integrated into the user&#39;s network to provide services to this network. The CT Gateway must then be started, either manually or automatically, as determined by the user. The processing which occurs during startup is illustrated in FIG. 2. Prior to this initialization, the user is required to configure valid IP address and ports for each of the PBX systems to be used, as well as configuring the master or listening socket  68  for the gateway. This master socket is used by the Gateway to listen for clients requesting connections to the server. Upon commencing initialization, the gateway connects to each switch node using the respective socket  74 . The processing begins as shown on FIG. 2 “Start Gateway Processing”  80 . The gateway first obtains the operating status and software version of the switching node at  84 . It will then query the individual device identifiers for the node  86  at  86  placing each device entity obtained into the Gateway database  88  and  90 . Once all the database has been obtained, the gateway will inform the PBX system node of the gateway presence at  92  and begin monitoring the node for any system event data at  94 . It will also configure the PBX system node so that the data it sends is in the format required by the gateway.  
         [0027]    Once all of the PBX systems have completed this initialization, the Gateway will begin to listen for applications request for service through the master socket  68 . The client application on the CTI application desktop  64  will attempt to establish communication with the Gateway by sending a logon message to the gateway by way of the master socket  68 . Once the Gateway has recognized this application, it will send a “power up” response indicating it is ready to begin servicing the client&#39;s application on the CTI application  64 . The logon message sent by the client must take the form of: 
         &lt;ByteCount&gt;&lt;Type of Socket&gt;&lt;Password&gt;0×00[&lt;AppName&gt;0×00] 
         [0028]    where:  
         [0029]    ByteCount—(the byte count for the data being passed)  
         [0030]    Type of socket—passed as hex 87 (0×87)  
         [0031]    Password—up to 15 ASCII characters  
         [0032]    Appname—up to 32 ASCII characters. This is optional, but it is useful in knowing which socket connection is connected to which application when running multiple applications.  
         [0033]    Upon receiving the Power Up response from the CT Gateway  66 , the application on the desktop  64  is free to send any commands to allow it to perform its task. In most cases this will require the application to begin monitoring a device or set of devices. This results in monitor start request arriving at the CT Gateway  66  from the application desktop  64 . These commands are processed and are routed to the proper PBX node socket  74  by determining which device is affected in the command and mapping it to the corresponding PBX node using the gateway database  72 . In the event that the gateway determines that a monitor already exists for a particular device, it will not need to forward the command to a PBX node, but simply creates a suitable response for the application on desktop  64  immediately. In the event the device is not yet monitored, a command is sent to a PBX node which will shortly thereafter send a command response back to the socket  74 . The Gateway receives this command response and determines which application the response is destined for and routes it to the application on the desktop  64  only.  
         [0034]    In the event the monitored device generates an event, the event is routed to the socket  74 , which is polled shortly thereafter by the gateway processor  70 . At this point the Gateway  66  determines the device and type of event and then determines if any application will require this event. The event then is forwarded onto any interested applications, such as those on the desktop  64 .  
         [0035]    The system also routinely polls the application sockets  68  looking for commands to send to the phone system. The commands are processed and the affected extension information is used along with the database  72  to determine to which switch socket(s)  74  connection the command is to be routed. After the command(s) is sent and acknowledged by the switch node which posts a response at socket  74 , the Gateway then subsequently routes the response to the associated application which originated the command.  
         [0036]    In the course of normal processing, as data arrives at a socket  74  for each PBX node, the system uses the sequence number of the message to determine if there has been any data lost between messages. In the event that there has been lost data, the Gateway  66  generates an error event to each application which uses the specified node and once again performs initialization processing on that node. Once the node completes re-initialization the application processing can recommence. While the node is not responding, the application is unable to route commands to the switching system (unless they are node aware, as described subsequently).  
         [0037]    In special cases, an application can command the Gateway  66  to let it be more intelligent about the topography of the switching environment. It allows the application to know what nodes are present, as well as to be less affected by the failure of any one node. This mode of operation is referred to as node awareness and allows a single node failure not to adversely affect the behavior of the external application. In the event of loss of communication at any single node, the Gateway  66  sends the application a link status failure and attempts to recommence communication with the failing phone system node. The application is still able to send commands to all of the other operating nodes. This is in stark contrast to a non-node aware application, which cannot communicate with any node until communication is restored to the failing node.  
         [0038]    In the course of normal processing, extensions can be added or deleted from a switching node. These changes result in extension change events sent to the socket  74  for the associated PBX node. Upon polling the socket, the gateway  66  adjusts the database  72  with respect to the extension change event.  
         [0039]    [0039]FIG. 3 is an example of one manner of programming which illustrates an operation of the system to complete initialization. The system, at  104 , allows each software application to internally initiate and begin sending device monitor sequences to open communications links with associated devices. If some devices already are being monitored, confirmation is made at  106 ; and then the device numbers (telephone extensions) and the node numbers mapping is done at  108 . After the device and nodes mapping, the system issues translated device “extension numbers” for initialization commands at  1   10 ; and these are provided with application numbers and command ID mapping at  112 . Software applications then are confirmed to the PBX nodes at  114 ; and command sequence numbers are initialized and associated with the software applications at  116 . The operation of the sequence number verifier, that is the Gateway and the PBX node, are accomplished at  11   8 ; and the software application initialization is completed at  120 . The system is now prepared to operate as a communications link which is transparent to the users at each of the different PBX nodes  10 ,  20 ,  30  and  40 .  
         [0040]    As processing continues in an example of a typical gateway process, as shown in FIG. 4, the Gateway monitors the polled data arriving from each CTI application. If the Gateway receives a command from an application (system event) at  130 , the Gateway  66  invokes acceptable call handling routines at  132 , and issues appropriate call control commands at  134  in accordance with the standard PBX operating procedures. These commands are supplied to the device number and node number mapping for translation at  136 , and from there, the command is sent to the appropriate PBX system node and device, as shown at  138 . This means that the system node IP socket  74  (FIG. 1) which is specific to the device (extension number) is selected; and the information is transmitted back out through the LAN and through the site server  52  through the WAN  50  to the appropriate selected one of the PBX&#39;s  10 ,  20 ,  30  or  40  which has that particular extension  14 ,  24 ,  34  or  44  associated with it. In the example shown in FIG. 4, the command is processed and acknowledged by the PBX node at  140  in a conventional manner, and a confirmation at  141  is sent back through the Gateway  66  which determines through a lookup table at  142  which CTI application is waiting for this command confirmation message. The Gateway  66  sends the command confirmation message at  142  to the appropriate CTI application at  144 . At  146 , the basic all control sequence is complete; and a call is effected between the calling and called parties without either of the parties knowing whether they are operating within a single one of the PBX systems  10 ,  20 ,  30  or  40 , or whether the call has been handled from one system, through the Gateway, to another. As far as the individual parties are concerned, the call appears to be handled entirely within the same PBX.  
         [0041]    As processing continues in conjunction with the sequence described in FIG. 4, the CT Gateway also monitors the polled data arriving from each of the PBX nodes at  160  (FIG. 5). If the event received indicates a system change at  161 , the Gateway  66  reads the nature of the update at  160  and makes changes to the mapping provided by the specific device number (extension number) and PBX node device translation database at  162 , and supplies this information to the device number and node number mapping memory. These changes are made automatically.  
         [0042]    The changes also occur on an ongoing basis; and once a change has been committed to the database at  162 , the translation of packets from that point on is done according to the revised translation mapping information stored in the database ( 72  of FIG. 1). These changes occur continuously and transparently to the software applications that are utilizing the gateway in the manner described above in conjunction with FIG. 4. The overall process is designed for the applications software to be able to complete the processing of the appropriate call event and continue to provide real time control of the selected devices connected to each PBX node. If the event does not reflect a system change, or once the system change update has been completed by the Gateway, the Gateway then determines which, if any, CTI applications want to receive the event at  164 . The Gateway determines this by looking at which monitor sessions each CTI application has initiated. The Gateway send the event to all appropriate CTI applications through the LAN at  166 . The event handling sequence is complete at  168 .  
         [0043]    The system can be programmed differently to employ the Gateway  66  in operations other than the ones shown by way of example in FIGS. 3, 4 and  5 . Other versions of the system may incorporate telephone switches that purely exist within the computer servers. The network topologies for such systems are capable of combining the functions of the CT Gateway process into one (presumably a “main” system) PBX node to eliminate the need for a separate server to house the CT Gateway process. Then, any CT application will be able to login to the main phone system server to obtain a consolidated data stream from the entire network of PBX nodes. Such a version further simplifies the network topology and makes processing more efficient.  
         [0044]    The foregoing description of the preferred embodiment of the invention is to be considered as illustrative and not as limiting. Various changes and modifications will occur to those skilled in the art for performing substantially the same function, in substantially the same way, to achieve substantially the same result, without departing from the true scope of the invention as defined in the appended claims.