Patent Publication Number: US-7912038-B2

Title: System and method for utilizing circuit switched and packet switched resources

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 09/668,696 filed Sep. 22, 2000 now U.S. Pat. No. 6,882,640 of the same title. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to communication systems, and more specifically, to a voice communication system operable to utilize both circuit switched and packet switched resources. 
     BACKGROUND OF THE INVENTION 
     Most telephone service subscribers use plain old telephone service (POTS) for placing ordinary voice calls. POTS is typically delivered over a subscriber loop between the subscriber&#39;s home or office and the local telephone company central office. The telephone company central offices provide a circuit switched network to establish connections between subscribers. A circuit switched connection provides relatively low and constant signal delay and guarantees full throughput for the duration of the call. Circuit switching, thus, provides a generally high quality of service connection for switched voice calls. 
     Data networks employ packet switched networks to move data in separate, small blocks (packets) based on the destination address in each packet. Circuit switching and packet switching differ in many respects. Circuit switching statically reserves the required bandwidth in advance, whereas packet switching acquires and releases it as it is needed. With circuit switching, any unused bandwidth on an allocated circuit is just wasted. With packet switching it may be utilized by other packets from unrelated sources going to unrelated destinations, since circuits are not dedicated. 
     A further difference between circuit and packet switching is the charging algorithm. Packet carriers usually base their charge on both the number of bytes (or packets) carried and the connect time. Transmission distance usually does not matter with packet switching. With circuit switching, the charge is based on the distance and time only, and not the traffic. Circuit switched networks and packet switched networks have traditionally occupied different spaces within offices. Circuit switched networks are typically used for phone calls and packet switched networks are typically used to handle data. However, due to the reach of phone lines and the efficiency and low cost of data networks, the two technologies may be beneficially used together. 
     Multi-line products are often required for small offices, home offices, or similar applications. However, the costs for equipment and service make it impractical for multiple phone line installations. VoIP (Voice over Internet Protocol) packet switched service can be used to provide additional voice channels without requiring additional phone lines. There are situations, however, where VoIP may not be suitable since this technology typically suffers from quality of service issues. 
     There is, therefore, a need for a system and method that allows for dynamic allocation of packet switched and circuit switched resources based on a user&#39;s needs to provide multiple voice channels without requiring additional multi-line equipment. 
     SUMMARY OF THE INVENTION 
     A system and method for utilizing circuit switched and packet switched resources are disclosed. A voice communication system configured for routing calls from multiple users to circuit switched or packet switched resources generally comprises a hub in communication with at least one circuit switched channel, at least one packet switched channel, and a plurality of user devices. The system further includes a controller operable to select the circuit switched channel or the packet switched channel for connection with one of the user devices and a routing device operable to route the call from the user device to the selected channel. 
     The controller may be configured to select the channel based on quality of service, cost of the call, or status of the user, for example. 
     The network devices may be, for example, computers or telephones, and may be coupled to the hub by wires or in communication with the hub by wireless means. The user devices may be configured to utilize voice over Internet protocol, for example. 
     In another aspect of the invention, a voice communication system generally comprises a hub operable to provide circuit switched resources and packet switched resources to a plurality of user devices in communication with the hub to connect a user with a telephone network. The system further includes a means for selecting one of the circuit switched and packet switched resources for connection with one of the user devices and means for routing a call from the user device to the selected resource. 
     A method of the present invention for completing a voice connection generally comprises receiving a call request at a communication system coupled to at least one circuit switched channel and at least one packet switched channel. One of the circuit switched channel and packet switched channel is selected to connect the call with a telephone network. The method further includes establishing a voice channel with the telephone network over the selected channel. 
     The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, drawings, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustrating one embodiment of a system of the present invention for utilizing circuit switched and packet switched resources. 
         FIG. 2  is a schematic illustrating circuit switching. 
         FIG. 3  is a schematic illustrating packet switching. 
         FIG. 4  is a block diagram illustrating an exemplary arrangement of components of a hub of the system of  FIG. 1 . 
         FIG. 5  is a schematic illustrating one embodiment of a hub configured for communication with wireless devices. 
         FIG. 6  is a flowchart illustrating a process for allocating circuit switched and packet switched resources while optimizing quality of service. 
         FIG. 7  is a flowchart illustrating a process for allocating circuit switched and packet switched resources based on a user&#39;s status. 
         FIG. 8  is a flowchart illustrating a process for allocating circuit switched and packet switched resources while optimizing cost. 
         FIG. 9  is a flowchart illustrating a process for notifying a user that a circuit switched channel has become available. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is presented to enable one of ordinary skill in the art to make and use the invention. Descriptions of specific embodiments and applications are provided only as examples and various modifications will be readily apparent to those skilled in the art. The general principles described herein may be applied to other embodiments and applications without departing from the scope of the invention. Thus, the present invention is not to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail. 
     Referring now to the drawings, and first to  FIG. 1 , a system of the present invention is shown. The system is used in the context of a communication system having a port or hub type device  20  which mediates external resources with internal distribution. As shown in  FIG. 1 , the device  20  has both circuit switched and packet switched resources available to it. As further described below, the system combines traditional circuit switched phone lines with packet switched resources, such as VoIP, to create a multi-line function. 
     The circuit switched network is schematically shown in  FIG. 2 . When a user (or computer) places a telephone call, the switching equipment within the telephone system seeks out a physical “copper” (or fiber, radio, etc.) path all the way from the user&#39;s telephone  30  to the receiver&#39;s telephone  32 . Each of the rectangles  38  represents a carrier switching office (end office, toll office, etc.). In this example, each office  38  has three incoming lines and three outgoing lines  40 . When a call passes through a switching office  38 , a physical connection is established between the line on which the call came in and one of the output lines (shown as dotted lines  44 ). Once a call has been set up, a dedicated path between both ends exists and will continue to exist until the call is finished. The elapsed time between the end of dialing a number and the start of ringing may be ten seconds or more on long-distance or international calls. During this time, the telephone system is hunting for an available path. For many computer applications, (e.g., point of sale credit verification) long setup times are undesirable. Once the setup has been completed, the only delay for data is the propagation time for the signal. The circuit switched network provides a congestion free path. 
     A schematic illustrating a packet switched network is shown in  FIG. 3 . Packet switched networks move data in separate, small blocks (packets  48 ) based on a destination address in each packet. When received, packets  48  are reassembled in the proper sequence to make up the message. The six rectangles  50  represent switching offices. The packets  48  are queued in the last switching office for subsequent transmission. With packet switching, a router examines each packet to determine its source and destination address and then forwards the packet to the next router in the path toward the destination. This architecture permits efficient statistical multiplexing of traffic, however, it is poorly suited for applications requiring assured throughput or low/constant delay, since no bandwidth is reserved or guaranteed with conventional packet switching. Thus, there are some applications in which circuit switched networks are better suited and other applications in which packet switched networks are more desirable. Also, there may be cases where circuit switching is preferred, but it is still acceptable to use packet switching, if circuit switched resources are not available. 
     The system of the present invention includes logic that is used to allocate either circuit switched or packet switched resources based on requirements of the user or availability of resources. For example, the resources may be allocated based on whether the user needs high quality of service or low cost service, as further described below. 
     Referring again to  FIG. 1 , the hub  20  is connected to a line  60  having both a circuit switched phone channel and a data channel capable of handling packet switched data. The hub  20  may be connected to these resources via an ADSL (Asymmetric Digital Subscriber Line), for example. ADSL is a local loop transmission technology that simultaneously transports digital data and analog voice (e.g., POTS) both downstream and upstream via one pair of wires. ADSL typically implements a digital subscriber line with a maximum data rate from the central office to the subscriber (i.e., downstream bit rate) which is higher than the maximum available data rate from the subscriber to the central office (i.e., upstream bit rate). Analog voice is transmitted at baseband frequencies and combined with pass-band data transmission via a low-pass filter (not shown). The present invention is not dependent on any one protocol. It is to be understood that other types of transmission may be used such as ISDN, DSL, XDSL (where X is any type of DSL variant such as ADSL, HDSL, or VDSL) or any other suitable type of transmission that provides both circuit switched and packet switched functionality. The system may include, for example, a network interface device (NID), which includes the low-pass filter which extracts the voice-band signals. The NID typically includes a means for separating voice frequency signals from data signals. Preferably, a splitter separates voice frequency signals from the data traffic sharing the subscriber loop wire pair. For example, to separate POTS from data traffic, the splitter typically includes a high-pass filter and a low-pass filter. To separate POTS voice signals, the low-pass filter blocks high frequency signals and passes only lower voice frequency signals on a conventional POTS loop. To recover data traffic, the high-pass filter blocks low frequency signals leaving only high frequency data traffic signals to be sent out on a separate data network loop. 
     It is to be understood that the system shown in  FIG. 1  is only one example of a communication network system in which the present invention may be utilized. For example, the hub  20  may have more than one ADSL connected thereto to provide additional circuit switched and packet switched channels. 
     The hub  20  functions as a conduit between the circuit and packet switched resources and equipment connected thereto. As shown in  FIG. 1 , the hub  20  is connected to a plurality of user devices such as telephones  64  and computers  68 . These devices  64 ,  68  may be connected to the hub  20  either by wires or wireless means. A network (e.g., LAN (local area network), WLAN (wireless LAN), or any other type of network) may be connected to the hub  20 . The hub  20  thus creates a multi-line presentation to the network using a combination of the circuit switched and packet switched resources. 
       FIG. 4  schematically illustrates one embodiment of hub  20 . The hub  20  includes a routing device  70  operable to route calls between the circuit and packet switched channels and the user devices  64 ,  68 . The router  70  is preferably controlled by a controller  72  (or other suitable device) that may be programmed to automatically select which service (either circuit switched or packet switched) to use. The controller  72  may be preprogrammed to follow logic such as described below, or may be programmed by a user entering data into a user input device  74  which is coupled to the controller via user interface  78 . It is to be understood that the function of the routing device  70  and controller  72  may be incorporated into a single device. Also, the routing device  70  and controller  72  may be integral with the hub  20  or external thereto. The router  70  and controller  72  may share a single processor or have separate processors. 
       FIG. 5  illustrates one example of the system configured for interface with wireless devices (telephone  64 , computer  68 ). The computer  68  includes a network interface card (NIC) configured for receiving and transmitting signals to an antenna  80 . The antenna is connected to RF port  82  which interfaces with a baseband controller  84 . The baseband controller  84  is coupled to a voice path  86  and a data path  88 . The voice path  86  is connected to a digital signal processor (DSP)  90  which is coupled to a line interface  94  through voice path  92 . The line interface  94  is connected to the packet switched and circuit switched networks via line  60 . Data path  88  is connected to broadband interface  94  which is coupled to a broadband link  98 . 
     The controller  72  may be configured, for example, to use circuit switched service for voice applications when available to provide a high quality of service. However, when additional lines are needed and the circuit switched resources are not available, the system will allocate packet switched lines for voice applications. This process is shown in the flowchart of  FIG. 6 . An outgoing call is placed from one of the user devices at step  100 . If a circuit switched channel is available, the call is routed to the circuit switched channel and placed using POTS, for example (steps  102  and  104 ). If no circuit switched lines are available, the call is routed to the packet switched channel and placed using VoIP, or other suitable application (steps  102  and  106 ). 
     The controller  72  may also be configured so that circuit switched resources are reserved for preferred users. For example, one or more users (such as high level personnel in an office) may have a preferred status. A list of preferred users is preferably stored in a database within the controller  72 .  FIG. 7  illustrates a process for routing calls based on the status of the user placing the call in a system having more than one circuit switched channel available. When a user places an outgoing call (step  110 ) the controller  72  first checks to see if more than one circuit switched channel is available (step  112 ). If more than one channel is available, the call will be placed using circuit switched resources (step  114 ). If only one circuit switched channel is available, it will be reserved for a preferred user. Thus, if the user is a preferred user, the call will be routed to the circuit switched channel (steps  116  and  118 ). If the user does not have preferred user status, the call will be routed to the packet switched channel (steps  116  and  120 ). 
     Alternatively, if appropriate equipment is available on both ends of a call prioritization can be automatically provided for. For example, the high priority caller may place a call at a time when there are no available circuit switched channels available. There is, however, at least one circuit switched channel in use by a low priority user. Through a protocol, the equipment at each end may request to move the low priority call to a packet switched channel. The low priority call is then switched without interruption of service or inconvenience to the user. The free circuit switched channel is now available for use by the high priority user. 
     The controller  72  may also be configured to select a service based on cost of a call. For example, if a long distance call is made, the lower quality service (i.e., packet switched) may be acceptable since a cost saving is provided.  FIG. 8  illustrates a process for routing calls based on cost. When an outgoing call is placed, the controller  72  first checks to see whether it is a long distance call (steps  130  and  132 ). If the call is a long distance call, it is routed to the packet switched channel (step  134 ), if not the call is routed to the circuit switched channel (step  136 ). The controller  72  may also route calls based on the location of the call (e.g., local or international). 
     The hub  20  may be configured to notify a user that has placed a call with the packet switched resources when a circuit switched channel is available, so that the user can hang up and make a new call using the circuit switched channel. This process allows a user to place a new call using the circuit switched service if the caller prefers a higher quality line. As shown in  FIG. 9 , the hub  20  notifies the user when a circuit switched channel becomes available (steps  140 - 144 ). The notification may be a message or signal played over the phone. The hub  20  may reserve the circuit switched line if the user selects to use it so that another user does not take the line, while the notified user hangs up and places a new call. If appropriate equipment is available on both ends of a call, as previously described, the call may be automatically switched to the circuit switched channel when it becomes available without the need for user intervention or call termination and redial. 
     The hub  20  may also be configured such that the user can inquire as to what resources are available before placing a call. For example, a user may not want to place a call using VoIP and therefore choose to wait until a POTS line is available. 
     It is to be understood that the logic described above for routing calls are only examples and that other configurations may be used without departing from the scope of the invention. 
     As can be observed from the foregoing, the system of the present invention provides numerous advantages over conventional systems. The system allows users to utilize conventional circuit switched services when available, thus providing traditional voice quality of service. However, when additional lines are needed, the system uses packet switched services (e.g., VOIP) to make additional lines available. Thus, a single connection can provide multiple phone lines. 
     Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations made to the embodiments without departing from the scope of the present invention. Accordingly, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.