Abstract:
Methods and systems for interfacing packet and circuit telephony operations in a distributed telecommunications network. Initially, one or more digital circuit switches can be associated with the distributed telecommunications network. Thereafter, one or more network transmission elements within the distributed telecommunications network can be connected to one or more of the digital circuit switches. One or more broadband switches can then be associated with one or more of the network transmission elements, such that the broadband switches thereof interface with network transmission elements and the digital circuit switches to coordinate combined circuit and packet signaling, routing and calling processing services among varying terminals of the distributed telecommunications network.

Description:
TECHNICAL FIELD 
   The present invention is generally related to telecommunications networks. The present invention is additionally related to telecommunications switching networks. The present invention is also related to telecommunications network architectures that provide communications among varying calling parties in multiple switching networks. 
   BACKGROUND OF THE INVENTION 
   Telecommunications switching networks traditionally have included SS7 signaling capabilities for communications over a telephone-signaling network. Such communications are primarily carried out utilizing a 64 kbits/s bearer channel that utilizes time division multiplexing (TDM,) and which is usually referred to as a narrowband network. This traditional switching network can be manufactured and supported by devices and systems such as the 5ESS® Switch which is manufactured by Lucent Technologies. A new generation of digital switching systems is evolving utilizing higher-bandwidth bearer channels and optical cable (OC) interfaces as the transmission medium to carry data and voice traffic. This new type of switch can provide significant bandwidth improvement, and is usually referred to as a broadband switch. 
   To inter-network bearer traffic between narrow and broadband switches, switch operators have begun utilizing transmission network elements to interface between narrowband (e.g., TDM) and broadband networks where the transmission network element requires no change to the narrowband switch transmission and signaling interfaces or procedures. At the same time, an on-going control information signaling standard, which is known as a Bearer Independent Call Control (BICC), and which is currently under development by the ITU standard committee and industry accepted procedures such as Internet Device Control Protocol (IPDC), can distribute and provide signaling, control and user information directly between narrowband and broadband network elements 
     FIG. 1  depicts a block diagram generally illustrative of a prior art telecommunication circuit switch network  100  associated with a switch office. Network  100  generally includes an administrative module  102 , which can communicate with a communication module  104  that in turn can communicate with a switching module  106 , a switching module  108  and/or a number of other switching modules, up to and including a switching module  192 . 
     FIG. 2  illustrates a block diagram of the 64 kbps channel network for a prior art switching module  200 , which can include a telephone line/trunk unit (LTU)  208  that communicates with a time slot Interface (TSI)  210  and a TSI  202 . Switching module  200  can also include a LTU  206  that also can communicate with TSI  210  and a TSI  202 . A digital line interface (DLI)  212  and DLI  204  can also be included in switching module  200  and can both communicate with TSI  202  and TSI  210 . Through TSI  202  and  210 , any of LTU  206 , LTU  208 , DLI  204  and DLI  212  can communicate with each other. TSI  202  and  210  provide duplicated paths between units as a part of the redundancy and reliability architecture of digital circuit switching module  200 . In time division multiplexing and/or switching, the term “time slot” typically refers to a slot belonging to voice, data or video conversation, which can be occupied with conversation or simply left blank. The slot, however, always remains present. The capacity of the switch or transmission channel can be determined by keeping track of the number of slots present. A “time slot interface” or TSI is thus limited in the number of conversations it can support by the number of time slots it can interchange from one unit to another. 
     FIG. 3  depicts a block diagram of a prior art circuit switch telephone call path configuration  300 . In this figure, the redundancy and reliability architecture of the digital switch is implicit. For example, TSI  328  in switching module  320  represents two physical TSI mechanisms that interconnect, for example, LTU  324  and DLI  326 . As indicated in  FIG. 3 , a communications module  302  is composed of a switching fabric time-multiplexed switch (TMS)  304 , which is generally associated with a link interface (LI)  306 , and link interfaces  310 ,  312 , and  314 . Communications module  302  thus can communicate with prior art switching modules  320  and  330 . Switching module  320  is composed of an LTU  324  and an LTU  322 , which can communicate with a TSI  328 , which in turn communicates with a DLI  326 . Similarly, prior art switching module  330  includes an LTU  334  and an LTU  336 , which communicates with a TSI  340 , which in turn can communicate with a DLI  338 . LTU  336  of switching module  330  can communicate with a terminal  344  (e.g., a telephone), while LTU  324  of switching module  320  can communicate with a terminal  342 . 
   In general, a circuit switch provides a physical, dedicated path (i.e., time slot) for a call when it goes through the switching matrix. Because this path is dedicated to the call, no other callers can use that switch path until the call is ended. Since the call has an end-to-end dedicated circuit for the duration of the call, the switch is called a circuit switch. Circuit switching is used for voice switching and to support data services that have a constant bit rate (CBR). Circuit switching is called synchronous because the user&#39;s information is transmitted in a specific time slot, and only in that time slot. 
   Indeed, today&#39;s voice or telephone networks use this concept of a dedicated path, not just in the switch but through all transmission portions of the network as well. When a person places a voice call, a dedicated path is established through every switch and transmission line needed to connect the call before the person being called ever hears the telephone ring. This concept of a dedicated path guarantees high-quality, almost error-free transmission for the call. And since the average voice conversation is about three to four minutes long, network switch resources used to set up the path can be reused over and over during the course of the day. 
   Packet switches, in contrast, do not utilize dedicated paths. Packet switches originally were designed for data traffic that comes in bursts with a variable bit rate (VBR), so switching resources are shared, that is, assigned on an as-needed, first-come, first-served basis. When a burst of data comes in, resources are assigned for that burst. At the end of the burst of data, the resources are available for the next burst of data, regardless of the user. Since a customer&#39;s data can arrive at the switch at any time, packet switching is called asynchronous. 
   The present inventors have identified a number of problems with the prior art architectures and configurations discussed above. For example, a serious problem associated with the narrowband-broadband interface occurs with architectural changes from synchronous to asynchronous networks. The complexity of conversion for circuit-to-packet telephony or packet-to-circuit telephony within the domain of the network infrastructure, with no modification to existing digital circuit switches, can create unwanted interruption and unreliable services. The present inventors thus believe that the prior art telecommunications architectures and systems do not provide an adequate interface for narrowband and broadband communications and that improved telecommunication methods and systems are needed. 
   BRIEF SUMMARY OF THE INVENTION 
   The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
   It is, therefore, one aspect of the present invention to provide improved switching capabilities for a telecommunications network. 
   It is another aspect of the present invention to provide improved combined circuit and packet switching capabilities for a telecommunications network. 
   It is yet another aspect of the present invention to provide improved methods and system for interfacing narrowband and broadband telecommunications functions with one another. 
   It is still another aspect of the present invention to provide improved methods and systems for communication among varying calling parties in multiple switches of a distributed telecommunications network. 
   The aforementioned aspects of the invention and other objectives and advantages can now be achieved as will now be summarized. Methods and systems for interfacing packet and circuit telephony operations in a distributed telecommunications network are disclosed herein. Initially, one or more digital circuit switches can be associated with the distributed telecommunications network. Thereafter, one or more network transmission elements within the distributed telecommunications network can be connected to one or more of the digital circuit switches. One or more broadband switches can then be associated with one or more of the network transmission elements, such that broadband switches thereof interface with the network transmission elements and the digital circuit switches to coordinate combined circuit and packet signaling, routing and calling processing services among terminals of the distributed telecommunications network. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention. 
       FIG. 1  depicts a block diagram generally illustrative of a prior art telecommunication circuit switch network associated with a switch office; 
       FIG. 2  illustrates a block diagram illustrative of a prior art switching module of a digital circuit switch; 
       FIG. 3  depicts a block diagram generally illustrating prior art approaches to circuit telephony systems utilized in telecommunication switch networks; 
       FIG. 4  illustrates a block diagram of a switching module, which can be implemented in accordance with an embodiment of the present invention; 
       FIG. 5  depicts a block diagram of a network transmission element having narrowband and broadband hardware interface capabilities, in accordance with an embodiment of the present invention; 
       FIG. 6  illustrates a block diagram of a telecommunications system composed of circuit and packet telephone long distance and metropolitan digital switches, formed in part from switching modules and protocol units, in accordance with an embodiment of the present invention; 
       FIG. 7  depicts a block diagram of a telecommunications system composed of circuit and packet telephone long distance and metropolitan digital switches, formed in part from switching modules and protocol units, in accordance with an embodiment of the present invention; and 
       FIG. 8  illustrates a block diagram illustrative of a system that includes the interconnection of a switching module and a network transmission element, in accordance with an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate an embodiment of the present invention and are not intended to limit the scope of the invention. 
     FIG. 4  illustrates a block diagram of a switching module  400 , which can be implemented in accordance with an embodiment of the present invention. Switching module  400  generally includes a telephone line/trunk unit (LTU)  402  which can communicate with a time slot interface (TSI)  418 , which in turn is associated with an ethernet card (EC)  420  and a peripheral line interface (PLI)  422 . TSI  418  and EC  420  can also be associated with one or more peripheral line interfaces  424  and/or  426 . It can be appreciated by those skilled in the art a number of other PLI&#39;s can also be associated with TSI  418  and/or EC  420 , depending upon particular telecommunications design and architectural considerations. The number of PLI&#39;s discussed here is not considered a limiting feature of the present invention, but is presented for general illustrative and edification purposes only. 
   Switching module  400  can also include an LTU  404 , which can communicate with TSI  418  and/or a TSI  406 . LTU  402  can communicate with TSI  418  utilizing communications line  411 , while LTU  404  can communicate with TSI  418  via communications line  409 . Similarly, LTU  402  can communicate with TSI  406  utilizing a communications line  407 , while LTU  404  can communicate with TSI  406  via a communications line  405 . TSI  406  can further be associated with a PLI  410  and/or an EC  408 . Additionally, TSI  406  and/or EC  408  can be associated with PLI&#39;s  412 ,  414  and/ 416 . 
     FIG. 5  depicts a block diagram of a network transmission element  500  having narrowband and broadband hardware interface capabilities, in accordance with an embodiment of the present invention. Network transmission element  500  generally includes a peripheral and control timing card (PCTC)  508 , which can communicate with a plurality of cross-connect multiplexers  510 . 
   Additionally, network transmission element  500  includes a PCTC  506 , an EC  502 , and an EC  504 , which also can communicate with the plurality of cross-connect multiplexers  510 . EC  502  can communicate with the cross-connect multiplexers via line  503 , while EC  504  similarly can communicated with the cross-connect multiplexers via line  505 . PCTC  506  can communicate with cross-connect multiplexers utilizing line  507 , and similarly, PCTC  509  can communicate with cross-connect multiplexers via line  509 . Network transmission element  500  further includes a circuit-packet or packet-circuit conversion card (CPPCCC)  514 , which communicates with cross-connect multiplexers  510  via a line  511 . Similarly, network transmission element  500  can also include a CPPCCC  516  that can communicate with cross-connect multiplexers  510  via a line  513 . 
     FIG. 6  illustrates a block diagram of a telecommunications system  600  composed in part from circuit and packet telephone switching modules, in accordance with an embodiment of the present invention. The redundancy and reliability architecture of the switching modules is implicit in the diagram. System  600  is composed of a switching module  632  that is generally analogous to the switching module  400  depicted in  FIG. 4 . Switching module  632  thus includes an LTU  634 , which communicates with a TSI  636  that is associated with at least one EC  640  and at least one PLI  638 . Switching module  632  is generally associated with a terminal  630  (i.e., a telephone). Switching module  632  can also communicate with a network transmission element  646  via a line  644  in the form of an IPDC, or other device control protocol, message. 
   It can be appreciated by those skilled in the art that respective communications from the switching modules  632  and/or  610  to the network transmission elements  646  and/or  624  are generally not implemented as standard external trunks, at least from the perspective of a digital switch. For example, an ISUP trunk to network transmission elements  646  and/or  624  is not a requirement of one or more embodiments of the present invention. Embodiments of the present invention do require, however, that the digital switch possess knowledge of the fact that the interface to network transmission elements  646  and/or  624  is a TDM bearer channel (e.g., see lines  642  and  615 ) that is controlled by a protocol such as, for example, BICC, wherein the digital switch is aware that it is interfacing with a bearer independent network implemented in ATM, IP, etc. 
   Thus, for example, a broadband switch  628  can communicate with switching module  632  via network transmission element  646  and a TDM circuit, which is generally represented in  FIG. 6  by a line  642 . Similarly, broadband switch  622  can communicate with switching module  610  via network transmission element  624  and a TDM circuit represented by line  615 . Note that communications between broadband switch  622  and network transmission element  624  can occur over a communications line  623 . Similarly, communications between broadband switch  628  and network transmission element  646  can occur over a communications line  629 . Additionally, communications between broadband switch  628  and broadband network  626  can occur over a communications line  652 , while communications between broadband switch  622  and broadband network  626  generally can occur over a communications line  654 . 
   Note that a broadband switch, such as broadband switch  628  can be configured as an ATM switch. The acronym “ATM” as utilized herein generally refers to ATM (asynchronous transfer mode), which is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path. The pre-specified bit rates for ATM systems are either 155.520 Mbps or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps. Along with Synchronous Optical Network (SONET) and several other technologies, ATM is a key component of broadband ISDN (BISDN). Those skilled in the art can appreciate, however, that the use of an ATM switch is not considered a limiting feature of the present invention. A broadband switch, such as broadband switches  628  or  622 , can be implemented in other contexts. The present invention is not confined the utilization of ATM as a broadband switching technology. For example, an IP packet network could be utilized in place of an ATM switching network. Thus, reference to ATM switches and networks herein is made for illustrative and edification purposes only. 
   Note that network transmission elements  646  and  624  are generally analogous to the network transmission element  500  of  FIG. 5 . Broadband switch  628  generally can communicate with switching module  632  via network transmission element  646 . Communications between network transmission element  646  and switching module  632  can take place over lines  642  and  644 . Line  642  can be implemented, for example, as a TDM circuit, while line  644  can be implemented via a communication link such as carry Ethernet frames and IPDC communications. Similarly, network transmission element  624  can communicate with broadband switch  622 . Broadband switch  628  and broadband switch  622  can communicate with one another utilizing a broadband network  626  (e.g., an ATM core network or an IP packet network), thereby promoting packet telephony capabilities thereof. Broadband switch  622  can additionally communicate with a switching module  610  via network transmission element  624 . Switching module  610  generally communicates with network transmission element  624  via lines  613  and  615 , which can respectively be configured (although not necessarily) as IPDC and TDM communication mechanisms. Line  615  can represent, for example, a TDM circuit, while line  613  can represent communications in the form of an IPDC message carried in an Ethernet frame. In general, all communications between a digital switch as represented by switching modules  632  and/or  610  and a broadband switch as represented by broadband switch  628  and/or  622  occur through the network transmission elements  646  and/or  624 . 
   It can be appreciated by those skilled in the art that broadband network  626  can be composed of a plurality of broadband nodes. For example, one type of a broadband network that can be utilized in association with the embodiments discussed herein may be based on Lucent&#39;s CBX 500™ Multiservice wide area network (WAN) Switch and/or PacketStar™ PSAX Broadband Multiservice Media Gateways. This particular type of ATM core network can be constructing over an existing SDH (Synchronous Digital Hierarchy) infrastructure, which enables a telecommunications provider to offer services to business and/or residential customers, such as voice, data, video and broadcasting services. It can be appreciated by those skilled in the art that features such as Lucent&#39;s CBX 500™ multiservice wide area network (WAN) Switch and/or PacketStar™ PSAX Broadband Multiservice Media Gateways are discussed herein for illustrative purposes only and are not considered limiting features of the present invention. 
   Switching module  610  is generally analogous to the switching module  400  of  FIG. 4 , and includes at least one EC  612 , at least one PLI  614 , which are both associated with a TSI  616  that in turn can communicate with an LTU  618 . A terminal  620  (e.g., a telephone) is generally associated with switching module  610 . Switching module  610  additionally can communicate with a protocol unit  608 , which in turn can communicate with external or internal network  606  (e.g., a CCS network). Similarly, switching module  632  can communicate can communicate with a protocol unit  602 , which in turn can communicate with the external or internal network  606 . Communication between protocol unit  602  and network  606  can take the form of SS7 and BICC signaling, as represented by line  604 . Similarly, communications between protocol unit  608  and network  606  can take place via SS7 and BICC signaling, as represented by line  607 . 
   Note that the term “SS7” refers generally to the signaling system 7 (SS7) protocol promulgated by the Consultative Committee for International Telegraph and Telephone (CCITT) or by the American National Standards Institute (ANSI). The acronym “BICC,” on the other hand refers to the Bearer Independent Call Control (BICC), which is a signaling protocol based on N-ISUP that is generally utilized to support narrowband ISDN service over a broadband backbone network without interfering with interfaces to the existing network and end-to-end services. BICC is fully compatible with existing networks and any system capable of carrying voice messages. BICC generally supports narrowband ISDN services independently of bearer and signaling message transport technology. 
     FIG. 7  depicts a block diagram of a telecommunications system  700  composed of circuit and packet telephone digital switches, in accordance with an alternative embodiment of the present invention. Note that in  FIGS. 6 and 7 , identical or analogous parts or elements are generally depicted by identical reference numerals. Thus, the system  700  of  FIG. 7  does not include a broadband network  626 , or broadband switches  628  or  622 . Instead, system  700  includes the same network transmission elements  646  and  624 , which can communicate with a broadband switch  702 . In general, broadband switch  702  depicted in  FIG. 7  can communicate with network transmission element  646  via a communications line  629 . Additionally, broadband switch  702  of  FIG. 7  can communicate with network transmission element  624  via a communications line  623 . An optional communications path may also exist in some embodiments of the present invention between network transmission elements  646  and  624 , as indicated by line  650 . It can be appreciated by those skilled in the art, however, that line  650  and any communications thereof between network transmission elements  646  and  624  are optional components only, and are not considered limiting features of the present invention. 
     FIG. 8  illustrates a block diagram illustrative of a system  800  that includes the interconnection of a switching module and a network transmission element, in accordance with an embodiment of the present invention. System  800  includes a network transmission element  824  that communicates with a switching module  802 . Note that switching module  802  represents an alternative switch embodiment from the switching module  400  of  FIG. 4 . Thus, switching module  802  includes an LTU  804  and LTU  806 . LTU  804  can communicate with a TSI  808  and/or a TSI  810 . TSI  808  can in turn can communicate with an EC  814  and a plurality of PLI&#39;s  815 . Similarly, LTU  806  can communicate with a TSI  810  and/or TSI  808 . TSI  810  can in turn can communicate with an EC  812  and the plurality of PLI&#39;s  816 . Note that redundant communications paths are thus available between LTU&#39;s  804  and  806  and TSI&#39;s  808  and  810 . Redundant communications paths are also available between TSI&#39;s  808  and  810  and the plurality of PLI&#39;s  816 . 
   Network transmission element  824  includes an EC  832  and an EC  826 . EC  832  of network transmission element  824  can communicate with EC  814  of switching module  802 . Similarly, EC  826  of network transmission element  824  can communicate with EC  812  of switching module  802 . Communications between EC  826  and  812  generally take place over a line  822 , while communications between EC  832  and EC  814  generally take place over a line  820  in the form of IPDC protocol signals. 
   Additional communications between network transmission element  824  and switching module  802  can take place over a TDM circuit, which is generally represented by a grouping of lines  818 , which comprise redundant communications paths thereof. Network transmission element  824  also includes a PCTC  830  and a PCTC  828 , which respectively communicate with one or more cross-connect multiplexers  834  that in turn are connected to a CPPCCC  836  and CPPCCC  837 . System  800  additionally includes a broadband switch  838  and a broadband switch  840 . Each broadband switch  838  and  840  can be composed of a plurality of interconnected OC cards. 
   It can be appreciate by those skilled in the art that a variety of types of broadband switches can be utilized in place of broadband switches  838  and  840 , such as, for example, ATM switches. It can also be appreciated by those skilled in the art that each broadband switch  838  and  840  can respectively be associated with one or more software modules, such as software modules  839  and  841 . The use of such software modules  839  and  841  is of course optional and is not considered a limiting feature of the present invention. Note that the term “module” as utilized herein generally refers to a software module, but may also refer to hardware equipment (i.e., physical modules), which may or may not operate independently of specific software. 
   Thus, the terms “module” and “software module” can be utilized interchangeably to refer to the same general function. In the computer programming and telecommunications arts, a “module” can be implemented as a collection of routines and data structures that performs particular tasks or implements a particular abstract data type. Modules generally are composed of two parts. First, a software module may list the constants, data types, variable, routines, and so forth that can be accessed by other modules or routines. Second, a software module may be configured as an implementation, which can be private (i.e., accessible only to the module), and which contains the source code that actually implements the routines or subroutines upon which the module can be based. Thus, when referring to a “module” herein, the present inventors are referring so such software modules or implementations thereof. 
   The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention. Those skilled in the art, however, will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. Other variations and modifications of the present invention will be apparent to those of skill in the art, and it is the intent of the appended claims that such variations and modifications be covered. The description as set forth is not intended to be exhaustive or to limit the scope of the invention. Many modifications and variations are possible in light of the above teaching without departing from the scope of the following claims. It is contemplated that the use of the present invention can involve components having different characteristics. It is intended that the scope of the present invention be defined by the claims appended hereto, giving full cognizance to equivalents in all respects.