Abstract:
A software-based telecommunications switch architecture with distributed supervision, network communications, and signal processing provides an expandable call volume handling capacity without having to add additional supervisory processing capability. The call signals are processed by a plurality of media control platforms which communicate with a supervisory network services processor and communicate with the network through a packet manager. The switch can be expanded by adding more media control platforms without the need to provide a new or additional network services processor or packet manager.

Description:
This application claims the benefit of priority under 35 U.S.C. 119(e) to two abandoned U.S. Patent Provisional Application Ser. Nos. 60/279,295 and 60/279,279, both filed on Mar. 28, 2001, the contents of each of said application being incorporated by reference herein. 
    
    
     This application is also related to the following U.S. Patent Applications: U.S. patent application Ser. No. 10/108,603 filed Mar. 28, 2002 entitled Distributed Architecture for a Telecommunications System; U.S. patent application Ser. No. 10/109,128 filed Mar. 28, 2002 entitled Method and Apparatus for a Messaging Protocol in a Distributed Telecommunications System; U.S. patent application Ser. No. 10/109,196 filed Mar. 28, 2002 entitled Method and Apparatus for Providing A Software Adaptation Layer in a Telecommunications System; U.S. patent application Ser. No. 10/115,435 filed Mar. 28, 2002 entitled Method and Apparatus for a Deriving a Standard MAC Address from A Physical Location; U.S. patent application Ser. No. 10/109,157 filed Mar. 28, 2002 entitled Method and Apparatus for A Centralized Maintenance System within a Distributed Telecommunications Architecture; and U.S. patent application Ser. No. 10/109,149 filed Mar. 28, 2002 entitled Method and Apparatus for Providing a Proprietary Data Interface in a Distributed Telecommunications System, the contents of each of said applications being incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     In a traditional PSTN network, calls are routed through dedicated switching assemblies. To expand the capability of this system, more or larger switching assemblies are utilized. Given the rapid expansion of telecommunications, in part owing to the increase in digital and wireless traffic, the switching system has had to rapidly expand to handle the call volume. 
     Computer networking technology and the Internet offer two models of flexibility and scalability that the telephone industry has looked to for the future. In that regard, industry groups have established the concept of the “Softswitch,” a software-based switching network. These efforts are described in part at two industry websites: the International Softswitch Consortium at www.softswitch.org and the Multiservice Switching Forum at www.msforum.org. 
     Notwithstanding this work, there remains a need for a switching system that may be easily scaled and can handle a variety of protocols and signalling formats (e.g., SS7, ATM, VoIP, MGCP, H.323, H.248). By breaking down the functions performed in a softswitch and distributing those functions over several computing platforms, a more flexible and scalable architecture is achieved. Further, by selectively providing different forms and levels of redundancy for the various platforms, a more reliable system can be obtained. Finally, by providing a platform that translates from one of the several external protocols to an internal, proprietary protocol, the switch can have universal application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a telephone system incorporating a soft switch; 
         FIG. 2  is a block diagram of a portion of a soft switch illustrating the fault tolerance and scalability of the switch. 
         FIG. 3  is a block diagram of an alternative telephone system incorporating a soft switch; and 
         FIGS. 4 and 5  are process flow diagrams for the systems of  FIGS. 1 and 3 . 
     
    
    
     DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 1 , the telephone system  10  has an originating central office  20  and a terminating central office  30  interconnecting subscribers  40  and  42 . In place of a traditional switching network, there is an ATM (asynchronous transfer mode) or IP (internet protocol) network  50  (or a network employing some other transmission medium). The central offices  20  and  30  are connected to each other through the network  50  via media gateways  60  and conventional interfaces such as TDM trunks. Subscribers may also connect to the soft switch  100  directly via access devices (e.g., integrated access devices [IADs] and cable modem termination system [CMTS]) or as packet subscribers, in lieu of conventional PBX, analog, and ISDN devices. 
     The routing of voice and data through the network  50  is controlled by a soft switch  100  comprising one or more media control platforms (MCPs)  140 , a network services processor (NSP)  180 , and a packet manager (PM)  200 . By establishing these various components of the soft switch  100 , the work is efficiently distributed over several elements. If desired, the work could be apportioned in a different fashion, for example, subdividing the media control platforms  140  or perhaps the packet manager  200 , or even combining certain of the elements. An integrated signaling gateway (ISG)  120  is also provided in the system  10  of  FIG. 1  and serves as an interface between the system  10  and the soft switch  100 . 
     When a subscriber wishes to place a call, the originating central office  20  sends a signaling message to the integrated signaling gateway  120 . The message may be in any suitable format such as SS7. The integrated signaling gateway  120  distributes the message to the media control platform  140  and also forwards outgoing messages (e.g., notifications of a call) to the terminating central office  30 . Additionally, the integrated signaling gateway  120  has responsibility for the integrity of the interconnections with the central offices  20  and  30 . Should one of these interconnections be damaged or otherwise be unable to function, the integrated signaling gateway  120  will attempt to reestablish them and the coordination with the central offices  20  and  30 . 
     The media control platforms  140  are responsible for controlling calls, including call setup and release. Media control platforms are logically assigned to a set of trunks, subscriber lines, or access devices, handling the originating and terminating sides of a call. Because the media control platforms each handle multiple trunks, lines or devices, perhaps 8000 apiece, it is conceivable that the originating and terminating trunks or lines could be assigned to the same media control platform. However, for clarity, a second media control platform  160  is shown in  FIG. 1 . 
     The network services processor  180  is responsible for call routing and maintains a database representative of the network. It also handles administrative, billing, call feature control, and maintenance functions, as well as overall supervision and configuration for the switch  100 . With respect to configuration of the network  50  and the soft switch  100 , the network services processor  180  maintains a network/switch configuration database  182  of the trunks and/or lines assigned to each of the media control platforms  140 ,  160 . The configuration database provides the media control platforms  140 ,  160  and the packet manager  200  with the information necessary to route calls from the originating endpoint  40  to the terminating endpoint  42 . In an actual implementation, the network/switch configuration database  182  could be subdivided into a number of databases, perhaps separating the switch configuration data from the network configuration. To maintain supervision over switching activities, the network services processor  180  further comprises a call status database  184  that holds the call states of the trunks and lines handled by the soft switch  100 . 
     When the network services processor  180  receives a routing request from the originating media control processor  140 , the network services processor  180  consults its database to determine the proper routing for the call and provides the routing information for the endpoints of the call to the media control platforms  140 ,  160  handling the originating and terminating sides of the call. Also, the network services processor  180  tracks the call states of the components of the soft switch  100  and the subscribers. Finally, the network services processor  180  is responsible for setting up subscriber and trunk features of the links and subscribers. 
     The packet manager  200  provides an Interface between the soft switch  100  and the media gateway  60  (or another access device). Externally, i.e., outside of the soft switch  100 , the packet manager  200  supports the protocol employed by the network  50  (e.g., ATM, IP, SIP, MGCP, H.323, H.248). Internally, the packet manager  200  utilizes a proprietary protocol, which may include a legacy protocol ported to the environment of the soft switch  100 . Except for initial configuration and maintenance issues where the packet manager  200  communicates with the network services processor  180 , the packet manager  200  communicates primarily with the media control platforms  140 ,  160  and the media gateways  60 . The media control platforms  140 ,  160  provide information to the packet manager  200  for connecting each side of the call through the network  50 . The packet manager  200  then passes this information (i.e., “connection information”) on to the media gateways  60  on the originating and terminating sides of the call. 
     The soft switch is shown by itself in  FIG. 2  (less an optional integrated signaling gateway  120 ). The components of the soft switch  100  communicate with each other over a local area network (LAN)  110 . As can be seen from this figure, the soft switch  100  also provides for redundancy by designating multiple elements for several of the components of the soft switch  100 . For example, real-time duplicates of the network services processor  180  and the packet manager  200  can be provided, with each of the pairs (i.e., the network services processors and the packet managers) operating in a microsynchronous mode and providing fault tolerant redundancy. Alternatively, either or both of the network services processor  180  and the packet manager  200  could be operated in a software redundant mode, where the load is shared between two processors and synchronization and backup is achieved through software. 
     The media control platforms  140 ,  160  can be teamed in pairs that share the load in an “active/active” mode (each media control platform being “active”). If one of the platforms fails, the other takes over. For any given pair of media control platforms, they will each be cognizant of the current status of calls the other is handling by way of a synchronization channel  190 . Although the synchronization channel  190  is shown as a separate link in  FIG. 2 , the synchronization information would likely travel over the local area network  110 , and not over a separate communications channel. Therefore, in the event one has to assume the load of the other, the transition can be effected almost immediately without having to provide call status information. The trunk assignments (0001-8000, 8001 — 16000, etc.) are arbitrary and may be assigned in quantities and orders suitable to the application. Conceivably, greater protection could be achieved by providing media control platforms in groups of three or more. 
     Additionally, the internal communications links, e.g., one or more local area networks  110 , may be provided with redundancy to insure a communications path in the event one of the connections fails. During operation, each pair of links will share the traffic load. In the event of a failure or some other inability of one of the links to carry traffic, the other link of a given pair will take over the entire traffic load until the former can be repaired or replaced. 
     To maximize the utility of the soft switch  100 , the protocols used in the switch  100  are shielded from the outside. The packet manager  200  translates external commands to a form recognized by the software utilized by the soft switch  100 . This is explained in greater detail in the above-referenced U.S. patent application Ser. No. 10/109,128, titled “Method and Apparatus for a Messaging Protocol in a Distributed Telecommunications System,” filed Mar. 28, 2002, and incorporated by reference herein. 
     The system  10  shown in  FIG. 1  utilizes the current SS7 infrastructure. The soft switch  100  also may be used in a system that uses the Internet or some other network for signaling, as in an ATM or IP network, as illustrated by the system  210  shown in  FIG. 3 . Instead of sending call signaling from the central offices  20  and  30  to an integrated signaling gateway  120  (see  FIG. 1 ), all signaling is sent over the same paths as the voice or data. Thus, the subscribers  40  and other devices ultimately reach the network  50  through originating and terminating access gateways  300  and  320 . The signaling information that formerly entered through the integrated signaling gateway  120  now travels over links to the packet manager  200 . Otherwise the soft switch  100  behaves in the same fashion as the system  10  of  FIG. 1 . 
     How the systems function in establishing and ending a call is illustrated in the process flow diagrams of  FIGS. 4 and 5 . There, the origination or call setup and the release or tear down of a call are illustrated. Further, these diagrams show how the various operations are distributed over various portions of the soft switch  100 , rather than being handled by one monolithic processor. 
     To establish a call, beginning in  FIG. 4 , a subscriber (or equivalent) goes off hook (also referred to as “seizure”) and an origination message is generated and ultimately received by the “originating” media control platform  140 . This message includes the destination digits, i.e., the called party number. The originating media control platform  140  will then notify the network services processor  180  that a call is being requested, telling the network services processor  180  that the trunk or line is busy and request digit translation (call routing). 
     In turn the network services processor  180  will select an outgoing channel and notify a second media control platform  160  (the “terminating media control platform”) that a call is coming and at the same time will send the identity of the terminating media control platform  160  to the originating media control platform  140 . The two media control platforms  140 ,  160  will then communicate, exchanging information so that the respective gateways  60 ,  300 , or  320  can set up the proper connections to the network  50 . The call is then completed through the network  50 , achieving call setup or call status “talk.” 
     At some point, the call will end and the path will be released. The media control platform responsible for the first party to release the line will communicate this status change to the other media control platform and the network services processor  180 . Then, the media control platforms will notify their respective gateways that the path is to be torn down. The completes the release of the path. 
     Scalability is achieved by providing additional media control platforms as necessary to accommodate the number of trunks or lines serviced by the soft switch  100 , as shown in  FIG. 2 . Since the supervisory portion, i.e., the network services processor  180 , can handle an increasing number of trunks and similarly the packet manager  200  is capable of coordinating the connections to the network  50 , only the media control platforms need be expanded, as shown in  FIG. 2 . In this fashion, the soft switch  100  can be enlarged horizontally rather than adding separate, stand-alone switching systems which must be coordinated. Here, in the soft switch  100 , an expandable coordination and communication capacity is provided by the network services processor  180  and the packet manager  200 , respectively. 
     It should be understood that the division of labor set forth in  FIGS. 1-6  is one of many possibilities. For example, in  FIG. 2 , the packet manager  200  could have been split into two parts, one part handling call signaling communications and the other handling network communication issues. Similarly, the media control platforms and the packet manager could be combined, allowing for expansion of both as the network expands. This is noteworthy in the case of  FIG. 2  where the packet manager will handle an increasing load as the number of trunks served increases. Then, in the same fashion as the media control platform, the packet manager would be expanded by adding additional “packet manager processors” and the trunk load increased.