Abstract:
A system and method for providing analog telephone service, including E-911, service can be provided at a site that uses VoIP over SDSL and has no POTS lines, in the event of a power outage at the site. The system comprises a remote cross connect switch connected to an integrated access device, to a digital access multiplexer connected to a digital telecommunications network, and to a voice service gateway, the remote cross connect switch operable to supply a first connection between the integrated access device and the digital access multiplexer, a second connection between the integrated access device and the voice service gateway, and to switch between the first and second connections; and a network management system connected to the digital telecommunications network and to the remote cross connect switch, the network management system operable to receive a message from the integrated access device indicating that power supplied to the integrated access device has failed and to, in response, transmit a command to the remote cross connect switch to switch from the first connection to the second connection thus providing anolog voice service, and upon power being restored to the integrated access device, the integrated access device to notify the network management system, and in response to being notified, send a command to the remote cross connect switch which is operable to re-establish the original connection between the integrated access device and the digital access multiplexer, thus restoring VoIP over SDSL.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a system and method for providing analog telephone service when voice over IP service is interrupted due to power failure.  
         BACKGROUND OF THE INVENTION  
         [0002]    Voice over Internet Protocol technologies (VoIP) are making inroads against traditional Plain Old Telephone Service (POTS). Voice-over-IP takes continuous analog voice, digitizes it, packetizes it, formats it to Internet Protocol (IP) and transfers it across a LAN or WAN to a destination where it is ultimately reconstituted back into continuous analog voice. Businesses are attracted to VoIP because it allows them to drastically reduce their long-distance phone charges. Digital Subscriber Line (DSL) is one of the signal protocols being used to carry VoIP services. One version of DSL is Symmetrical DSL (SDSL), which is a capable of supporting voice and data over IP via a 2-wire line. SDSL is attractive because of its relatively low installation cost and its ability to handle multiple voice channels along with data over 2-wire lines. Furthermore, businesses that deploy VoIP over SDSL can eliminate the need for additional Public Switched Telephone Network (PSTN) lines. However, a problem arises when Voice over SDSL is implemented in a site that does not have POTS. Since SDSL equipment is powered from the customer premises, VoIP service over SDSL is interrupted if there is a power outage at the customer premises. The problem is particularly acute in the case of emergency 911 service (E-911), which likewise is interrupted in the event of a power outage at the customer premise (CP).  
           [0003]    This problem with the prior art is illustrated in more detail in FIG. 1. In a synchronous high-speed data link, such as SDSL, communications is established by installing an Integrated Access Device (IAD)  102  at the customer premises  104  and connecting it via a dedicated 2-wire copper line  106  to an SDSL concentrator (DSLAM)  108 . Typically, DSLAM  108  is located in the central office of the competitive local exchange carrier (CLEC)  110 . Since DSLAM  108  is typically owned and operated by an entity other than the ILEC, this arrangement is termed co-location (COLLO). SDSL has enough bandwidth to support simultaneous voice and data traffic over IP without the need for additional POTS lines.  
           [0004]    The problem lies in the inherent nature of Voice-over-SDSL, which relies on IAD  102 , which draws power from customer premises  104 . If there is a power failure at the customer&#39;s premises, then the client loses both voice and data communications. Although IAD  102  has some limited power back-up facility, once the batteries are depleted, the customer is left without power, even for emergency E-911 voice service.  
           [0005]    By comparison, an analog POTS line receives its power from the central office so that in the event of a power outage at the customer premise  104 , the analog handsets would still be available for E-911 service.  
           [0006]    Presently, to avoid this problem, the customer would be forced to purchase an additional analog voice line, thereby undermining the whole reason for using voice over DSL in the first place. A need arises for a technique by which analog telephone service, including E-911, service can be provided at a site that uses VoIP over SDSL and has no POTS lines, in the event of a power outage at the site.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is a system and method for providing analog telephone service, including E-911, service can be provided at a site that uses VoIP over SDSL and has no POTS lines, in the event of a power outage at the site.  
           [0008]    The system comprises a remote cross connect switch connected to an integrated access device, to a digital access multiplexer connected to a digital telecommunications network, and to a voice service gateway, the remote cross connect switch operable to supply a first connection between the integrated access device and the digital access multiplexer, a second connection between the integrated access device and the voice service gateway, and to switch between the first and second connections; and a network management system connected to the digital telecommunications network and to the remote cross connect switch, the network management system operable to receive a message from the integrated access device indicating that power supplied to the integrated access device has failed and to, in response, transmit a command to the remote cross connect switch to switch from the first connection to the second connection.  
           [0009]    The connection between the integrated access device and the remote cross connect switch is capable of carrying digital subscriber line signals and analog telephone signals. The digital access multiplexer is a Digital Subscriber Line Access Multiplexer (DSLAM).  
           [0010]    When the integrated access device is connected to the digital access multiplexer, the connection between the integrated access device and the digital access multiplexer carries a digital subscriber line signal. The voice service gateway is connected to a public switched telephone network. When the integrated access device is connected to the voice service gateway, the connection between the integrated access device and the voice service gateway carries an analog telephone signal.  
           [0011]    The network management system is further operable to receive a message from the integrated access device indicating that power supplied to the integrated access device has resumed and to, in response, transmit a command to the remote cross connect switch to switch from the second connection to the first connection. The connection between the integrated access device and the remote cross connect switch is capable of carrying digital subscriber line signals and analog telephone signals. The digital access multiplexer is a digital subscriber line access multiplexer. The integrated access device is connected to the digital access multiplexer, the connection between the integrated access device and the digital access multiplexer carries a digital subscriber line signal. The voice service gateway is connected to a public switched telephone network. The integrated access device is connected to the voice service gateway, the connection between the integrated access device and the voice service gateway carries an analog telephone signal. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The details of the present invention, both as to its structure and operation, can best be understood by referring to the accompanying drawings, in which like reference numbers and designations refer to like elements.  
         [0013]    [0013]FIG. 1 is a block diagram of a prior art telecommunications system implementing voice over SDSL service.  
         [0014]    [0014]FIG. 2 is an exemplary block diagram of telecommunications system, according to the present invention, implementing voice over SDSL service with emergency access to analog telephone service.  
         [0015]    [0015]FIG. 3 is an exemplary flow diagram of a process of operation of the present invention, implemented in the system shown in FIG. 2.  
         [0016]    [0016]FIG. 4 is an exemplary block diagram of telecommunications system, according to the present invention, implementing voice over SDSL service with emergency access to analog telephone service.  
         [0017]    [0017]FIG. 5 is an exemplary flow diagram of a process of operation of the present invention, implemented in the system shown in FIG. 4  
         [0018]    [0018]FIG. 6 is an exemplary block diagram of a network management system shown in FIGS. 2 and 4.  
         [0019]    [0019]FIG. 7 is an exemplary block diagram of a Remote Cross Connect Switch (Loop Management System—LMS) shown in FIGS. 2 and 4.  
         [0020]    [0020]FIG. 8 shows an exemplary matrix board included in the Remote Cross Connect Switch shown in FIG. 7.  
         [0021]    [0021]FIG. 9 shows an example of cross point connection in the matrix board shown in FIG. 8.  
         [0022]    [0022]FIG. 10 shows an exemplary cross point connection pin used to establish a cross point connection in the matrix board shown in FIG. 8.  
         [0023]    [0023]FIG. 11 shows an exemplary robotic cross connector included in the Remote Cross Connect Switch shown in FIG. 7.  
         [0024]    [0024]FIG. 12 is an exemplary block diagram of an apparatus that verifies proper connection of a cross point connection pin shown in FIG. 10.  
         [0025]    [0025]FIG. 13 shows an example of matrix boards in relation to the robotic cross connector.  
         [0026]    FIGS.  14 - 19  illustrate some standard  3  dimensional connection paths, which are completed by the Remote Cross Connect Switch in response to commands.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    Voice-over-IP takes continuous analog voice, digitizes it, packetizes it, formats it to Internet Protocol (IP) and transfers it across a LAN or WAN to a destination where it is ultimately reconstituted back into continuous analog voice. Digital Subscriber Line (DSL) is one of the signal protocols being used to carry VoIP services. DSL provides the capability to transmit broadband data over existing two-wire telephone lines. There are several versions of DSL in common use. Asymmetric DSL (ADSL) provides greater bandwidth for downstream data than for upstream data. In addition, ADSL reserves a portion of the available channel bandwidth for support of traditional analog telephone service (Plain Old Telephone Service (POTS)). ADSL is aimed primarily at the residential market. Another version of DSL is Symmetric DSL (SDSL). SDSL provides equal bandwidth in both the upstream and downstream directions and does not provide support for POTS. SDSL is better suited to business applications, such as network server communications, etc. Voice may be supported by SDSL by use of Voice-over-IP (VoIP) service over SDSL, known as Voice-over-SDSL (VoSDSL). Since SDSL equipment is powered from the customer premises, VoIP service over SDSL is interrupted if there is a power outage at the customer premises. The problem is particularly acute in the case of emergency 911 service (E-911), which likewise is interrupted in the event of a power outage at the customer premise (CP).  
         [0028]    The present invention overcomes the E-911 problem with VoSDSL by switching the connection of the Integrated Access Device (IAD), which is located at the customer premises, from a DSL connection to a standard POTS line, in the event of a power outage at the Customer Premises (CP). In order to accomplish this task, a Remote Copper Cross Connect Switch would automatically re-connecting an affected subscriber line to an analog voice line.  
         [0029]    The arrangement by which the present invention switches the IAD to a standard POTS line is shown in FIG. 2. As shown in FIG. 2, equipment located at customer premises  202  includes IAD  204 , with AC power supply  205 , at least one telephone set  206  and at least one data processing system  208 . Telephone set  206  is typically a standard analog telephone set and is connected by an analog line to IAD  204 . LAD  204  digitizes the analog voice signal from telephone set  206 , packetizes the digitized signal, formats the packets to Internet Protocol (IP) and transfers the packets via dedicated  2 -wire copper line  210  to the CLEC central office  212  using SDSL. Data processing system  208  is connected to IAD  204  and transmits and receives digital data via IAD  204 .  
         [0030]    Equipment located at CLEC Central Office  212  includes Remote Cross-Connect Switch  214 , Digital Subscriber Line Access Multiplexer (DSLAM)  216 , and Voice Service Gateway (VSG)  218 . DSLAM  216  is a system that links customer DSL connections to at least one high-speed Asynchronous Transfer Mode (ATM) line, which provides connection to IP network  220 . Typically, IP network  220  is the Internet, but may be any public or private data transport network. VSG  218  links analog telephone lines to the Public Switched Telephone Network  222 , typically via a telephone switch, such as a Class  5  Switch  224 .  
         [0031]    Network management system (NMS)  226  is connected to IP network  220  and also has a private connection  228  to Remote Cross-Connect Switch  214 . Note that network  228  may also make use of network  222 . NMS  226  can send and receive messages from any device communicatively connected to IP network  220 , such as IAD  204 . NMS  226  can control the configuration and operation of Remote Cross-Connect Switch  214  over connection  228 . Likewise, NMS  226  can determine the status and configuration of Remote Cross-Connect Switch  214  over connection  228 .  
         [0032]    An example of a suitable cross-connect switch  214 , is the CONTROLPOINT™ switch available from NHC. As used herein, the terms cross-connect and cross-connect switch are intended to mean any switch capable of reliably interconnecting telecommunications signals, including voice and data signals, from inputs to outputs under the influence of internal or external control signals. The terms are intended to encompass any such switch and control systems, including loop management systems. To illustrate the operation of an embodiment of a cross-connect switch  214  and the manner in which it is controlled, the CONTROLPOINT switch available from NHC is hereafter briefly described.  
         [0033]    The CONTROLPOINT solution is NHC&#39;s integrated non-blocking copper cross-connect system that helps CLECs and ILECs qualify and provision DSL and other services remotely without the need to enter the CLEC&#39;s COLLO or ILEC&#39;s CO. The CONTROLPOINT solution works with third party equipment such as Harris, Hekimian and Tollgrade Remote Test Units, enabling the cross-connect to be used as a test access platform for rapid loop qualification. The CONTROLPOINT solution may be deployed for DSL test access for local loop qualification, provisioning, migration and fallback switching. The CONTROLPOINT solution is intended to work with every major DSLAM vendor.  
         [0034]    The CONTROLPOINT cross-connect hardware has a matrix size and loopback capabilities that allow multiple services to be provisioned and migrated remotely on-the-fly and on-demand, thereby minimizing truck-rolls needed to qualify and provision high speed data services. The CONTROLPOINT solution allows the service provider to migrate users to higher speed data services quickly. The CLEC has the ability to use any available port on the DSLAM for fallback switching thus providing added value to both the CLEC and the subscriber.  
         [0035]    The CONTROLPOINT solution is managed via two-key elements: CONTROLPOINT CMS  226  and CONTROLPOINT CMS Remote (Controller) (not shown). CONTROLPOINT CMS  226  is the control and management software for NHC&#39;s CONTROLPOINT Solution. Element  226  is later referred to generically as network management system (NMS) and may also be referred to as a terminal. CONTROLPOINT CMS  226  communicate with NHC&#39;s CONTROLPOINT Copper Cross-Connect  214  via the CONTROLPOINT CMS Remote Controller to allow voice and high-speed data service providers to take full control of their copper cross-connect infrastructure.  
         [0036]    CONTROLPOINT CMS controls and tracks the physical connections within the CONTROLPOINT matrix, along with vital subscriber and equipment information. CONTROLPOINT CMS features an intuitive Graphical User Interface (GUI) for greater ease of use. Port connections involve a simple drag &amp; drop operation. CONTROLPOINT CMS&#39;s integrated database tracks CONTROLPOINT subscriber/service connections and organizes the network into multi-level geographical views by country, city and site location.  
         [0037]    CONTROLPOINT CMS Remote is the SNMP control interface for NHC&#39;s CONTROLPOINT copper cross-connect switch, which allow the CONTROLPOINT cross-connect  214  to be managed via NHC&#39;s CONTROLPOINT Control and Management Software (CMS) or managed via third party Network Management System (NMS). The CONTROLPOINT CMS Remote is connected to an Ethernet LAN and is accessible via standard SNMP commands. The CONTROLPOINT CMS Remote connects to CONTROLPOINT cross-connect via serial link. The device receives standard SNMP commands from the NMS or CONTROLPOINT CMS and communicates them to the CONTROLPOINT cross-connect. Support for API (application interfaces) within the CONTROLPOINT CMS Remote and CONTROLPOINT CMS allows for customization to support NHC&#39;s proposed line-sharing solution.  
         [0038]    While the CONTROLPOINT switching system may be used to implement the cross-connect switch, it will be understood that any remotely controllable cross-connect switching system may be implemented according to embodiments of the present invention. The cross-connect switch  214  and its controllers are hereafter referred to generically. Also, the terms cross-connect switch and cross-connect are used interchangeably.  
         [0039]    A process of operation of the present invention, implemented in the system shown in FIG. 2, in which the power to the customer premises fails, is shown in FIG. 3. It is best viewed in conjunction with FIG. 2. The process begins with step  302 , in which, in the normal situation, IAD  204  is connected by the Remote Cross-Connect Switch  214  to DSLAM  216 . This arrangement provides SDSL connection of data processing system  208  and VoSDSL connection of telephone set  206  to IP network  220 . In step  304 , electrical power provided at customer premises  202  by AC supply  205  fails. In step  306 , the power system of IAD  204  detects the power failure of step  304  and begins to supply back-up power to IAD  204 . The power system also notifies IAD  204  of the power failure. The power system of IAD  204  typically includes a battery back-up supply that can supply power for several hours.  
         [0040]    In response to the notification from the power system, IAD  204  sends a message to NMS  226  over the SDSL connection typically using the Simple Network Management Protocol (SNMP). SNMP is a set of protocols for managing complex networks that includes messages for indicating the status and proper function of devices. The message sent by IAD  204  to NMS  226  identifies IAD  204  and indicates that the power to IAD  204  has failed. In step  308 , NMS  226  receives the SNMP message indicating that the power to IAD  204  has failed. In response, NMS  226  generates and sends a command script to the Remote Cross-Connect Switch  214  to switch  230  the affected line, line  210 , from connection  232  with DSLAM  216  to connection  234  with VSG  218 . In step  310 , Remote Cross-Connect Switch  214  receives the command script from NMS  226  and switches  230  line  210  from connection  232  with DSLAM  216  to connection  234  with VSG  218 . In step  312 , analog service via line  210 , connection  234 , and VSG  218  is available for use.  
         [0041]    Although not shown in FIG. 3, IAD  204  also enters a failure mode, in which telephone set  206  is directly connected to line  210 . The failure mode of IAD  204  is maintained without power, thus the connection survives the expiration of the back-up power supply of IAD  204 . A process of operation of the present invention, implemented in the system shown in FIG. 4, in which the power to the customer premises resumes, is shown in FIG. 5. It is best viewed in conjunction with FIG. 4. The process begins with step  502 , in which, in the power failure situation shown in FIG. 2, IAD  404  is connected by Remote Cross-Connect Switch  414  to VSG  418 . This arrangement provides analog connection of telephone set  406  to VSG  418 . In step  504 , electrical power provided at customer premises  402  by AC supply  405  resumes. In step  506 , the power system of IAD  404  detects the power resumption of step  504  and begins to supply power to IAD  404 . The power system also notifies IAD  404  of the power resumption. In response to this notification, IAD  404  sends an SNMP message to NMS  426  identifying TAD  404  indicating that the power to IAD  404  has resumed. This may be accomplished via Voice service Gateway  418  which may also have access to network  420  and thus network  428 . In step  508 , NMS  426  receives the SNMP message indicating that the power to IAD  404  has resumed. In response, NMS  426  generates and sends a command script to Remote Cross-Connect Switch  414  to switch  436  the affected line, line  410 , from connection  434  with VSG  418  to connection  432  with DSLAM  416 . In step  510 ,  
         [0042]    Remote Cross-Connect Switch  414  receives the command script from NMS  426  and switches  436  the affected line, line  410  from connection  434  with VSG  418  to connection  432  with DSLAM  416 . In step  512 , SDSL connection of data processing system  408  and VoSDSL connection of telephone set  406  to IP network  420  is available for use. An exemplary block diagram of a network management system  600 , according to the present invention, is shown in FIG. 6. Network management system  600  is typically a programmed general-purpose computer system, such as a personal computer, workstation, server system, and minicomputer or mainframe computer.  
         [0043]    Network management system  600  includes processor (CPU)  602 , input/output circuitry  604 , network adapter  606 , and memory  608 . CPU  602  executes program instructions in order to carry out the functions of the present invention. Typically, CPU  602  is a microprocessor, such as an INTEL PENTIUM® processor, but may also be a minicomputer or mainframe computer processor. Input/output circuitry  604  provides the capability to input data to, or output data from, computer system  600 .  
         [0044]    For example, input/output circuitry may include input devices, such as keyboards, mice, touchpads, trackballs, scanners, etc., output devices, such as video adapters, monitors, printers, etc., and input/output devices, such as, modems, etc. Network adapter  606  interfaces network management system  600  with network  610 . Network  610  may be any standard local area network (LAN) or wide area network (WAN), such as Ethernet, Token Ring, the Internet, or a private or proprietary LAN/WAN, but typically, IP network  220  is the Internet. Note that this network may also be represented by serial dial-up. Memory  608  stores program instructions that are executed by, and data that are used and processed by, CPU  602  to perform the functions of the present invention.  
         [0045]    Memory  608  may include electronic memory devices, such as random-access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, etc., and electro-mechanical memory, such as magnetic disk drives, tape drives, optical disk drives, etc., which may use an integrated drive electronics (IDE) interface, or a variation or enhancement thereof, such as enhanced IDE (EIDE) or ultra direct memory access (UDMA), or a small computer system interface (SCSI) based interface, or a variation or enhancement thereof, such as fast-SCSI, wide-SCSI, fast and wide-SCSI, etc, or a fiber channel-arbitrated loop (FC-AL) interface.  
         [0046]    Memory  608  includes a plurality of blocks of data, such as IAD/Loop Management System (LMS) database  612  and scripts block  614 , and a plurality of blocks of program instructions, such as processing routines  616  and operating system  618 . IAD/LMS database  612  stores information relating to IADs and the LMS or Remote Cross-Connect Switches that are managed and controlled by NMS  600 . Scripts block  614  includes scripts that are transmitted by NMS  600  to Remote Cross-Connect Switches to control the connection of circuits. Processing routines  616  are software routines that implement the processing performed by the present invention, such as receiving SNMP messages, accessing IAD/LMS database  612 , transmitting scripts from script block  614 , etc. Operating system  618  provides overall system functionality.  
         [0047]    An exemplary block diagram of a Remote Cross-Connect Switch  700  is shown in FIG. 7. Switch  700  includes matrix boards  702 A and  702 B, robotic cross-connector  704 , control circuitry  706 , processor  708  and communication adapter  710 . Matrix boards  702 A and  702 B, an example of which is shown in more detail in FIG. 8, are multi-layer matrices of circuits having holes at the intersections of circuits on different layer. The holes, known as cross points, allow the connection of pairs of circuits on different layers by the use of conductive pins. To make a cross connections, a pin is inserted into one of holes in a matrix board, as shown in FIG. 9.  
         [0048]    Each pin, such as pin  1000 , shown in FIG. 10, has two metal contacts  1002 A and  1002 B on the shaft, which create the connection between the circuits on different layers of the matrix board.  
         [0049]    Robotic cross connector  704 , an example of which is shown in FIG. 11, provides the capability to move a pin to an appropriate cross point and to insert the pin to form a connection at the cross point or remove the pin to break a cross connection. The mechanism of robotic cross connector  704  is capable of movement in three dimensions, using a separate motor for movement in each dimension. For example, Z-coordinate motor  1102 , shown in FIG. 11, provides movement of the mechanism along the Z-axis..  
         [0050]    A pin is carried, inserted and removed by a robotic “hand”, such as hand  1104 A or  1104 B, which is part of robotic cross connector  704 .  
         [0051]    Control circuitry  706  generates the signals necessary to control operation of robotic cross-connector  704 , in response to commands from processor  708 . Processor  708  generates the commands that are output to control circuitry  706  in response to commands received from the network management system via communication adapter  710 .  
         [0052]    Once the pin has been inserted into the cross-point, robotic cross connector  704  then verifies that the connection has been successfully made, as shown in FIG. 12. In addition to the metal contacts on the shaft of each pin that form the connections, there is also a metal strip  1202  attached to each pin, such as pin  1204 . The robot verifies the connection by sending a small current from one hand  1206 A to the other hand  1206 B. The metallic parts of the robot hand are electrically insulated. Hand  1206 B is connected to the ground and hand  1206 A is connected to current detector  1208 . When the hands touches the metallic strip on the head of connect pin  1204 , current flows through the pin and the output of detector  1208  will change states if the insertion is good. If the insertion is not good then the output of detector  1208  will not change.  
         [0053]    An example of matrix boards in relation to the robotic cross-connector is shown in FIG. 13. As shown, typically two mother boards  1302 A and  130213 , upon which matrix boards  1304  are mounted, one robotic cross-connector  1102 , and the additional circuitry are grouped to form a cross connect system.  
         [0054]    FIGS.  14 - 19  illustrate some standard  3  dimensional connection paths, which are completed by the Remote Cross-Connect Switch in response to commands.  
         [0055]    Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.