Patent Publication Number: US-8983052-B2

Title: Method and apparatus for communication having critically assured services

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/341,532, filed Dec. 22, 2008, entitled “METHOD AND APPARATUS FOR COMMUNICATION HAVING CRITICALLY ASSURED SERVICES,” which claims the benefit of U.S. Provisional Application No. 61/188,245, filed Aug. 7, 2008, entitled “METHOD AND APPARATUS FOR CRITICAL ASSURED SERVICES,” the disclosures of which are incorporated by reference herein in their entirety. 
    
    
     FIELD 
     The disclosed technology relates generally to communication services, and more specifically, to telephony having critically assured services. 
     BACKGROUND 
     In some communication environments, communication service must always be available to a customer. For example, during times of war, the military must always have access to telephony service so that military orders and objectives may be sent and received. Once the lines of communication fail, it is very difficult for commanding officers to implement strategies without having all the information available to them. 
     Therefore, there is a need for a communication service that provides certain users within a network with uninterrupted service. For these critical subscribers, dual-switch connectivity needs to be provided to guarantee that these subscribers will be able to initiate and receive communications even when the subtending central office or access line is unable to process calls. These techniques should ensure that the subscriber&#39;s normal features and functions are not degraded or lost. (In this disclosure, “communications” refers to the sending or receiving of any type of media or information, such as, for example, audio, video, data, or fax. Accordingly, aspects of the disclosed technology may relate to ordinary telephony as well as to more sophisticated communications services. All of these types of services are meant to be included in the term “communications”. However, for simplicity, this disclosure, in large part, is written in terms of ordinary telephony.) 
     Additionally, there is a need for the network to automatically sense and reroute incoming/outgoing communications during outages at the subtending central office, link or access line, and to continue to provide class of service and features authorized to the subscriber&#39;s assigned telephone number. There is also a need for the network to automatically reset to a default configuration when the subtending central office, link or access line has been restored. 
     SUMMARY 
     The disclosed technology is directed towards a network for critical assured services. The network ensures that no single point of failure within a network will deny service at a user&#39;s location. To implement such a system, the disclosed technology provides customer premises equipment with diverse redundant connections to the network. The customer premises equipment may include a network management system, routers, DSLAMs, class 5 switches, channel banks, Network Operation Centers (NOCs) and an IP based A/B switch. 
     The A/B switch may include four ports. The first port is connected to the network management system over a dedicated Ethernet connection. The Ethernet connection is capable of sending and receiving messages and/or signals from and to the network management system. Based on the messages received, the A/B switch automatically switches the user&#39;s telephone service from the first point of presence to the second point of presence. For example, if the A/B switch is signaled that the first point of presence lost service or that the connection to the first point of presence is broken, the A/B switch will switch from the first point of presence to the second point of presence and then notify the network management system that the first point of presence lost service. The A/B switch and/or the network management system is capable of switching service back to an original configuration when service is restored at the first point of presence and the secondary point of presence is in an idle state. This capability ensures that in the event a call is in progress on the secondary point of presence, the call is not dropped when the disclosed technology switches back to an original configuration. 
     Messages and/or signals that are transmitted over the dedicated Ethernet line may include an auto-ping signal for determining if the first point of presence is operational. That is, the auto-ping signal may continuously monitor the first point of presence and switch the A/B device based on the response from the first point of presence. Other monitoring signals may include a class 5 switch call processing overload alarm and/or a signal transfer point disturbance alarm through the network management system and upon detection, the disclosed technology will send an appropriate command to the A/B device to switch from the first to second point of presence. The A/B device will remain latched in that position until the network management system sends a command to switch back to the first point of presence. 
     The first point of presence is transported over an Ethernet connection using copper media and DSL with plain old telephone service (POTS) to the primary 5ESS switch. The POTS service is dropped from the DSL at a splitter panel and connected to a primary 5ESS switch. The second point of presence of the A/B switch service is transported over a standard foreign exchange service connection using a diverse path to a secondary 5ESS switch. The second point of presence is connected between the third port of the A/B switch and the network management system over a modified service connection. The modified telephone service connection may include a wide area network connection having a foreign exchange service line card. The first point of presence provides a first dial tone to the A/B switch and the second point of presence provides a second dial tone to the A/B switch. The first point of presence and the second point of presence share a directory number that is interchangeable between the two when requested by the network. 
     The dual dial tone allows a CAS user to place outgoing calls immediately upon the IP AB switch changing from the one point of presence to the other. To switch directory numbers between the points of presence the network management system receives an appropriate handshake signal from the AB device and sends a routing table update command to a tele-management system. This allows incoming calls into network to be routed to appropriate 5ESS switch associated with the point of presence position on the AB device. The network management system may also send a pre-scripted batch release update command to the tele-management system to change a specified group of phone numbers within any given 5ESS switch failure scenario from the first point of presence to the second point of presence thereby allowing outgoing/incoming calls internal or external of the network to be directed along the second point of presence&#39;s secondary transmission path. The tele-management system may be a communication management Information tool (“COMIT”) server that processes all 5ESS translations via dedicated transmission control protocols (TCP) ports. 
     The fourth port of the A/B switch may be connected to a modem or other device. This modem or other device may receive telephone service from the A/B switch and may send this service to a standard desktop telephone regardless of which point of presence is sending the service. 
     In alternative embodiments, the NMS itself may be connected to the A/B switch by way of a CAS-type topology to provide even greater assurance of continued service. 
     These and other advantages of the disclosed technology will be apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a first embodiment of the present disclosed technology; 
         FIG. 2  is a block diagram showing a second embodiment of the present disclosed technology; 
         FIG. 3  is a block diagram showing a third embodiment of the present disclosed technology; and 
         FIG. 4  is a block diagram showing a fourth embodiment of the present disclosed technology. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosed technology is directed towards an apparatus for critical assured services (hereinafter, “CAS”) that provides dual-switch-connectivity telephony service to certain users service by a network management system (hereinafter “NMS”). 
       FIG. 1  shows a first design for the critical assured services  10 . This embodiment of the disclosed technology includes a network management system  11 , an A/B switch  17 , a first point of presence  14 , a second point of presence  19  and a tele-management system (TMS)  18 . 
     The A/B switch  17  is a multi-port switch that provides the disclosed technology with at least two separate and distinct telephony connections. (The switch may be configured for any type of communications protocol, format or technology.) The multi-port switch  17  has at least two ports for receiving telephony service from at least two separate and distinct points of presence (Ports A and B), at least one port for transmitting the telephony to a receiving device (Port D) and at least one port for sending and receiving operational and/or monitoring signals (Port C). 
     The port for sending and receiving operational signals, Port C in this embodiment, is connected to the network management system  11  over a dedicated line  24  via an edge router  12 . The dedicated line  24  is capable of sending and receiving messages and/or signals from and to the network management system  11 . Based on the messages received, the A/B switch  17  automatically switches telephone service from the first point of presence  14  to the second point of presence  19  during a cable outage or some other scenario. The A/B switch  17  may also be capable of switching service back to an original configuration when the first point of service  14  becomes operational. That is, the CAS design  10  may automatically detect when telephony cable outage is repaired and reset the A/B switch  17  position back to the A position. 
     The A/B switch  17  may be an IP-A/B switch that is an automatic, remotely controlled A/B switch for a communications circuit. Remote control may be accomplished via a 10/100 Ethernet port supporting TCP/IP protocols, e.g., HTTP (web browser), SNMP, and TCP messaging. The TCP protocol is used for direct computer control of the switch while automatic control is provided by the auto-ping feature. 
     The auto-ping feature may continuously monitor one or more network devices for operability and the A/B switch  17  will switch between the network devices based on the devices response to a periodic ping request. The A/B switch  17  may also be capable of auto-pinging multiple network devices. 
     In the first embodiment, the A/B switch is configured for the A (primary) and B (secondary) paths, but multiple paths, greater than two, are also contemplated. The primary path A and the secondary path B for the A/B switch  17  may be provided using any one of the following Physical Diverse Routing (PDR) methods: 
     1. Copper cables in separate conduits. 
     2. Wireless free space optic devices. 
     3. Existing fiber optic cables. 
     4. Existing microwave transmission facilities. 
     The A/B switch  17 , in this embodiment, changes from the “A” to “B” position when a first control signal corresponding to the auto-ping response for Port A fails within an expected response time. The CAS design may also automatically detect when a telephony cable outage is repaired and may reset the A/B switch position back to the A position. 
     In the event either “A” or “B” auto-ping failure occurs, an alarm, integrated into the NMS, is generated. When a failure occurs, the system may allow the NMS  11  to graphically display the CAS user&#39;s phone instrument  23  in the A or B position at a network operations center (NOC)  25  associated with the NMS  11 . 
     Port A of the A/B switch is connected to the first, or a primary-serving, point of presence (hereinafter, “POP”) or central office (hereinafter, “CO”)  14 . The primary POP  14  may be a 5ESS switch connected to a service delivery point (not shown) over an existing copper cable plant using DSL with POTS. 
     The primary POP  14  is connected to the network management system  11  via an edge router  12  and to Port A of the A/B switch  17  over a standard service connection. The path of the standard service connection starts at a 5ESS switch  14  and connects the 5ESS switch  14  to a DSL splitter panel  15  over a DSL POTS line. The DSL splitter panel  15  is then connected to a Digital Subscriber Line Access Multiplexer  16  (hereinafter, DSLAM) over an Ethernet cable. (A DSLAM allows voice grade service to be transported over an Ethernet connection to the DSL Modem which separates voice and data at the customer premises.) The A/B switch  17  and the first point of presence may be connected to a DSL modem  22  via RJ 45/48 interface connection. 
     The primary path A provides a first dial tone with a specific directory number to the A/B switch  17 . The A/B switch&#39;s normal position will be in the “A” position to allow incoming and outgoing calls from the primary POP  14 . 
     The secondary path B will be provided from a secondary POP  19 . The secondary POP  19  may also be a 5ESS switch that is located at different location from the primary POP  14 . The secondary POP  14  is known as a virtual tributary (VT) connection. 
     The second POP  19  is connected to the network management system  11  and to Port B of the A/B switch  17  over a modified service connection. The path of the modified service connection starts at the 5ESS switch  19  and is connected to a wide area network or WAN  20 ,  21  over a Primary Rate Interface (“PRI”) T1 trunk. WAN  21  may include a channel bank Foreign Exchange Service (“FXS”) line card that transmits signals over an encrypted T1 line provided by a commercial transport carrier. (In telecommunication, a foreign exchange service is a network-provided service, in which a telephone in a given local area is connected, via a private line, to a central office in another, i.e., “foreign”, exchange, rather than the local exchange area&#39;s central office.) 
     The WAN  21  may terminate at a DSL modem  22  via RJ 45/48 interface connection to Port B of the A/B switch  17  on a physically diverse cable path “B.” The secondary POP  19  provides a second dial tone to the A/B switch  17  on the physically diverse cable path. The second dial tone and the primary dial tone share the same directory number and the shared directory number is switched from one dial tone to the other via commands issued by the NMS to a tele-management system  18 . 
     The path of the second POP  19  to the network management system  11  starts at the secondary POP  19  and is connected to the tele-management system (“TMS”)  18  such as a COMIT (“Communication Management Information Tele-management system”) server. The COMIT server  18  is then connected to a gateway router  13  associated with the NMS  11  which is connected to the 5ESS ( 14  and  19 ) switching network over a dedicated TTY ports. 
     The NMS  11  may send 5MML commands to the COMIT server ( 18 ) to update the routing translation tables in the switching network ( 14  and  19 ) to process all incoming calls internal/external of the network from the first point of presence  14  to the second point of presence  19  when the first point of presence  14  is not operational. For example, after the network management system  11  receives notice that the first point of presence  14  is not operational, the network management system  11  transmits the 5MML command to the COMIT server  18  over the dedicated TTY port to the 5ESS switching network  18 . The COMIT server  18  then updates the routing translation tables for the specific directory number from the first point of presence  14  and inserts new translations in the routing tables for the specific directory number to the second point of presence  19  and vice versa. 
     The TMS  18  may be an approved tele-management system for 5ESS switch translations. For example, if the A/B switch  17  is signaled that the first point of service  14  lost service, the A/B switch  17  will switch from the first point of presence  14  to the second point of presence  19  and then notify the network management system  11  that the first point of service  14  lost service. A signal is then transmitted to the COMIT server to change the routing tables for a specific or group of directory number from Port A to Port B. This will allow outgoing/incoming calls internal or external of the NMS  11  to be directed to the secondary transmission path B in the event the primary cable path A is down. 
     The fourth port, Port D, of the A/B switch  17  may be connected to an analog, digital or ISDN telephone set  23  that may receive telephony service from the A/B switch  17  regardless which point of presence is sending the service. 
     In use, a first control signal will auto-ping the DSLAM device  16  associated with the primary POP  14  via the edge router  12 . A successful ping response signifies the primary cable path A is available and the A/B switch  17  will remain in the “A” position. If the ping response exceeds a specified delay time, the A/B switch  17  will automatically switch to the “B” position, and dial tone will be provided to the switch via the secondary POP  19 . 
     Simultaneously, a simple management network protocol (hereinafter, “SNMP”) trap from the IP AB switch is sent from port C Ethernet connection over the secondary path to the edge router  12  associated with the primary POP  14  and the NMS  11 . The NetExpert VSM gateway server (NMS) will process the SNMP message and send the 5E MML commands over a dedicated TTY port on the COMIT server  18 . The COMIT server  18  inserts the commands to the 5ESS switches within the network to remove the CAS directory number from the primary 5ESS switch  14  and insert the directory number into the secondary 5ESS switch  19 , offsite. 
     At the same time, an alarm trap from the IP-based A/B switch  17  will be routed to a gateway router  13 . The gateway router  13  at secondary POP  19  will transmit an alarm signal over the dedicated TTY port to the COMIT server  18 . The COMIT server  18  then executes a pre-scripted batch release update command to change switch routing tables for a specified group of phone numbers, e.g., the 555-XXXX thousand groups. This will allow outgoing/incoming calls internal or external of the NMS  11  to be directed to the secondary transmission path B in the event the primary cable path A is down. 
     The system may also include a monitoring signal that monitors for an overload alarm. In this mode, a second control signal monitors the primary 5ESS switch for overload alarms. A virtual service manager  26  (herein after, “VSM”) associated with the NMS  11 , e.g., an Agilent NetExpert, monitors for the overload message. In the event, the primary 5ESS switch  14  stops call processing, a CPU overload alarm will be transmitted to VSM  26  via the edge router  12 . This message will be an event trigger and the VSM  26  will transmit a SNMP trap to the A/B switch  17  signaling the switch to automatically switch to the “B” port. 
     The A/B switch  17  will then transmit a response SNMP trap to the NMS edge router  12  over the dedicated line signifying the switch to the “B” port. The edge router  12  then pings a dedicated TTY port to COMIT server  18  signifying the execution of a pre-defined APPTEXT which removes the CAS directory number from the primary 5ESS switch  14  and inserts the CAS directory number into the secondary, off-site 5ESS switch  19 . 
     At the same time, the alarm trap from the A/B switch  17  will be routed to the NMS router  13  at the secondary CO. The NMS router  13  transmits a 5ESS MLL command over a dedicated TTY port to the COMIT server  18  for all CAS users to be removed and inserted into the secondary 5ESS switch. The COMIT server  18  then executes a pre-scripted 5E Batch Release update command to change the 5ESS switch routing tables throughout the switching network. This will allow internal and external calls within the switching network be processed by the secondary 5ESS switch in the event the primary 5ESS switch  14  stops call processing. 
     The system may also monitor a Signaling System 7 (hereinafter, “SS7”) protocol that monitors for a signal transfer point (STP) reorder printer (ROP) for a “DPC Prohibited” alarm. In this mode, a third control signal monitors the SS7 link from a STP  27 , e.g. a Telelec STP, to the primary 5ESS switch  14 . (Tekelec&#39;s STP is a high-speed packet switch that allows carriers to deliver intelligent network features like credit card verification, caller ID, and 800 number look-up, using SS7 protocols.) In the event the CAS users primary 5ESS switch  14  shuts down, the STP  27  will transmit a “destination point code not allowed” message to the VSM  26 . The VSM  26  will then trigger off the SNMP trap to execute the same commands identified with the overload alarm signals. 
     In summary, CAS  10  will provide dual dial tone simultaneously to the CAS user A/B switch  17  from two POPs,  14 , and  19 , using diverse transmission paths A, B. The CAS design  10  provides non-blocking switched voice services even when potential outage conditions exist for command and control communicators with mission critical applications during a cable outage or switch failure. 
     The benefit of the CAS design solution is that the design provides assured voice communications to critical users. Assured service or connectivity is defined as the ability of the NMS to optimize call completion rates for all critical users despite degradation because of network disruptions, natural disasters, or surges during crisis of war. 
       FIG. 2  shows an alternative design for the CAS system  40 . In this embodiment, the system  40  is housed in two separate and distinct locations. Location 1 (L1) houses the primary POP  44 , the NMS  41 , A/B switches  48 ,  51 , the COMIT server  43  as well as other components necessary for the transmission of the primary telephony service. (In this embodiment, the NMS  41  is housed at L1 but the NMS  41  may be housed at L2 or some other location that is remote from L1.) Location 2 (L2) houses the secondary POP  54  and other components necessary for the transmission of the secondary telephony service. 
     At L1, the primary telephony service will be provided by a primary 5ESS switch  44  located in Building 1. The primary 5ESS switch  44  is connected to an ISDN DSL (IDSL) universal splitter panel  45 . The IDSL splitter panel  45  will blend ISDN voice data to a DSLAM 24-port ADSL/ADSL2+ universal splitter card  46  over POTS/ISDN transmission path. The ISDN service is transported from the splitter card  46  as an Ethernet connection over existing copper cable to an A/B switch  48 ,  51  at Building 2 and Building 3. For example, if the primary ISDN line is serving a military base, the 5ESS  44  will located in Building 1 and the ISDN service will be transmitted to Building 2 and 3 over existing intra-based copper cables. 
     The ISDN line is then cabled out from the A/B switches  48 ,  51  to IDSL modems  50 ,  52 , respectively. The modems will terminate at CAS ISDN phone sets  49 ,  53 , respectively. Under normal conditions, the CAS ISDN calls will be routed over the DSLAM  46  as IDSL to the primary 5ESS switch  44  located at Building 1. The primary 5ESS switch  44  is also connected to a COMIT server  43  via an edge router  42 , discussed more fully below. 
     The secondary telephony service is provided from a secondary 5ESS switch  54  at Locations 2 which is a remote location from Location 1. The secondary 5ESS switch  54  is connected to WAN  55  over a PRI trunk. The PRI trunk terminates to an existing channel bank of the WAN port  47 . The channel bank of WAN port  47  extends the secondary telephony service to the users&#39; A/B switches  48 ,  51  over an existing physically diverse cable plant. 
     In the event of an outage of the CAS user&#39;s primary transmission path or the primary 5ESS switch  44  stops call processing, the A/B switches  48 ,  51  will switch from port “A” to port “B”. 
     In use, the A/B switches  48 ,  51  will be configured for auto pinging of the DSLAM  46  at Building 1 over a dedicated Ethernet connection. If the ping response time fails, it is assumed the primary transmission path is out of service, and the A/B switches  48 ,  51  will change from the “A” to “B” position automatically allowing for outgoing and incoming calls to be placed from the secondary 5ESS switch  54 . 
     Simultaneously, the A/B switches  48 ,  51  will route an SNMP trap to the NMS edge router  42  signifying the primary transport is down. The NMS edge router  42  will transmit the appropriate 5ESS APPTEXT command to the COMIT server  43  at L1 to remove the directory number from the primary switch  44  and to insert the directory number into the secondary switch  54 . Simultaneously, the alarm trap from the IP-based A/B switches  48 ,  51  will be routed to the NMS router  42 . The NMS router  42  at L1 transmits a 5E MML command over a dedicated TTY port to the COMIT server  43 . The COMIT server  43  then executes a pre-scripted 5E Batch Release update command to change the 555-XXXX thousand groups to all 5ESS switch routing tables. This task will allow for incoming calls to be routed from the secondary 5ESS switch throughout the NMS. 
     The A/B switches  48 ,  51  are also capable of receiving SNMP traps from up to four SNMP managers and will switch from the “A” to “B” port upon acknowledgement. In the event that the 5ESS switch stops call processing at Location 1, the 5ESS switch may initiate, e.g., a CPU overload alarm. In this case, the NMS router will interface to the 5ESS and will execute the appropriate 5ESS APPTEXT command to the COMIT server  43 . The COMIT server  43  will then remove the CAS directory number from the primary 5ESS switch  44  and insert the number into the secondary switch  54 . 
     Additionally, the CPU overload SNMP trap will be sent to the user&#39;s A/B switches  48 ,  51 . The A/B switches  48 ,  51  will switch the user from port “A” to “B” automatically and send a handshake signal back to the NMS  41  for acknowledgement. 
     Simultaneously, the alarm trap from the IP-based A/B switches  48 ,  51  will be routed to the NMS router  42 . The NMS router  42  transmits an alarm signal over a dedicated TTY port to the COMIT server  43 . The COMIT server  43  then executes a pre-scripted 5E Batch Release update command to change the thousand groups to all 5ESS switch routing tables. The NMS  41  will verify that no calls are in progress on the secondary path prior to restoring service to the primary path. 
       FIG. 3  shows another exemplary design of a CAS system. In this embodiment, the system  60  will be housed in four separate and distinct locations. Location 1 (L1) will house a primary POP  63  and a NMS  61 , Location 2 (L2) will house a secondary POP  71  and a COMIT server  70 , Location 3 (L3) will house a WAN  73  having an FXS line card and Location 4 (L4) will house a critical user&#39;s phone  168  and an A/B switch  66 . Please note the NMS  61  may be housed at L1, L2 or some other location that is remote from L1 and L2. 
     The primary POP  63  is housed at L1 and may be a 5ESS switch. An analog line is cabled out from the 5ESS switch  63  to a DSL POTS splitter panel  64 . The DSL POTS splitter panel  64  blends the voice and data signal of the telephony service to a DSLAM ADSL2+ port line card  65 . The CAS service  60  will be extended as a 10/100 Ethernet transport from the DSLAM  65  to an A/B switch  66 . The primary POP  63  is also connected to the NMS  61  via a T1 line attaching an edge router  62  to the NMS  61 . 
     The secondary POP  71  is housed at L2 and may also be a 5ESS switch. A PRI trunk is provided from the 5ESS switch  71  and terminates to an existing channel bank in a WAN  72 . The WAN  72  is then connected to L3 over a leased T1 line. The secondary 5ESS switch  71  is also connected to the COMIT server  70  and then to a gateway router  69  that is connected to the NMS  61  over a dedicated TTY port. 
     The WAN  73  is connected to L3 via a bulk encrypted T1 from a commercial transport carrier. The T1 lease will provide a WAN connection between L2 and L3. The WAN  73  at L3 is equipped with a FXS line card. The telephony service from the secondary POP  71  will be extended from L3&#39;s Channel Bank FXS card to Location 4—the user&#39;s A/B switch  66  “B” port—via a physically diverse cable path from the primary path end to end. 
     At L4, the A/B switch  66  is connected to a DSL modem  67 . The modem  67  splits the voice and data circuit and terminates to the user&#39;s analog phone via POTS line. Incoming/outgoing calls will be processed in accordance with the switching network dialing plan under normal conditions. 
     In the event of an outage of the CAS users primary transmission path or primary 5ESS switch stops call processing, the A/B switch  66  will switch from port “A” to port “B” in the following method: 
     First, the A/B switch  66  at L4 is configured for auto-pinging the DSLAM  65  at L1 over the dedicated line. The A/B switch  66  is connected though the edge router  62  of the NMS  61  over the dedicated line. The auto-ping signal is transmitted over the dedicated line to the edge router  62  and the signal is transmitted to the DSLAM  65  of the primary POP  63  at regularly timed intervals. The ping response is due back within a certain time frame set by the A/B switch  66 . If the ping response time fails, then it is assumed the primary transmission path is out of service and the IP-AP switch  66  will change from the “A” to “B” position automatically allowing for outgoing and incoming calls to be processed through the secondary POP  71 . 
     In order to activate the secondary POP  17 , at the same time the A/B switch  66  changes channels, an SNMP trap is routed to the NMS edge router  62  at L1 signifying the primary transport is down. The NMS edge router  62  will transmit an appropriate 5ESS switch command to the COMIT server  70  at L2 to remove a directory number from the primary switch and insert the user&#39;s directory number into secondary switch  71 . 
     An alarm trap from the A/B switch  66  is also routed to the NMS router  69  at the secondary POP  71  at L2. The NMS router  69  at L2 transmits a5E MML command over a dedicated TTY port to the COMIT server  70 . The COMIT server  70  then executes a pre-scripted batch release update command. This command changes the routing tables for a certain set of directory numbers, e.g., 555-XXXX group. That is, all incoming calls will be routed to the secondary 5ESS switch at L2 for call processing. 
     The A/B switch  66  is also capable of receiving SNMP traps from up to four SNMP managers that will switch the A/B switch  66  from the “A” to “B” port receipt of the message. For example, in the event that the primary 5ESS  63  switch stops call processing at L1, the primary 5ESS switch  63  may initiate a CPU overload alarm. The NMS router  62  will interface to the 5ESS switch  63  and will execute an appropriate 5ESS command to the COMIT server  70  at the secondary 5ESS switch. The COMIT server  70  will then remove the CAS directory number from the primary 5ESS switch at L1 and insert the number into the secondary switch at L2. Additionally, the CPU overload SNMP trap will be sent to the user&#39;s A/B switch  66  over the dedicated line. The A/B switch  66  acknowledgement will switch the user from port “A” to “B” automatically and send a handshake signal back to the NMS  61  for acknowledgement. Simultaneously, the alarm trap from the A/B switch  66  will be routed to the NMS router  62  at the secondary POP. The NMS router  62  at L2 transmits an alarm signal over a dedicated TTY port to the COMIT server  70 . The COMIT server  70  then executes a pre-scripted release update command to change switching tables for the thousand groups. 
       FIG. 4  shows an exemplary design of a CAS system that is similar to  FIG. 3  except the WAN at Location 3 is connected to A/B switch over Free Space Optic (FSO)  80 ,  81 . In the event that the CAS submits orders to remote locations where diverse cable plant is non-existent, FSO may be a suitable option for deployment which will allow connectivity while maintaining security and safety. 
     The foregoing Detailed Description is to be understood as being in every respect illustrative and exemplary, but not restrictive, and the scope of the disclosed technology disclosed herein is not to be determined from the Detailed Description, but rather from the claims as interpreted according to the full breadth permitted by the patent laws. It is to be understood that the embodiments shown and described herein are only illustrative of the principles of the present disclosed technology and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the disclosed technology. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the disclosed technology.