Abstract:
A method and system for responding to security system inoperability due to damage of a telecommunications line interconnecting the security system to its central monitoring service system requires origination of a wireless telephone call. A wireless unit is interconnected to the security system and originates an emergency call upon detection of telecommunications line abnormalities. Upon establishing a call connection between the wireless unit and the central monitoring service system, the wireless unit relays dual tone multifrequency (DTMF) signals which identify the security system affected by the breach so that appropriate authorities may be dispatched. In alternative embodiments, the wireless unit is programmed to place calls to other designated telephone numbers.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to the applications of: 
     Akhtar Akhteruzzaman, Ronald J. Rees and Ian A. Schorr entitled “Method and System For Using Telecommunications Equipment For Detecting And Responding To A Security System Breach”; and 
     Akhtar Akhteruzzaman, Ronald J. Rees and Ian A. Schorr entitled “Method And System For Providing Redundancy In Security Systems Served By A Public Switched Telephone Network” which applications are assigned to the assignee of the present application and which are being filed concurrently herewith. 
     1. Technical Field 
     This invention relates to security systems and, more particularly, to detecting a security breach occurring as a result of an inoperable telecommunications line and alerting authorities of the breach via a wireless network. 
     2. Background of the Invention 
     Functional security systems alert dwelling occupants and emergency authorities of a violation of the secured premises. A typical security system includes a controller interconnected by wireless or wireline connections to sensors deployed at strategic locations throughout the dwelling. In a home, sensors are usually deployed in doorways, windows and other ports of entry. Motion sensors may also be placed strategically within the home to detect movement while carefully positioned smoke and heat sensors detect the presence of fire. 
     Security systems are interconnected to a central monitoring service system via a telecommunications line. The central monitoring service system is maintained by a security service provider and continuously monitors all activated security systems for sensor breaches. A sensor breach occurs when a sensor detects the opening of a door or window or the presence of movement or fire. A sensor breach causes the sensor to send a signal to the controller of the security system. Responsive to receiving a breach signal, the controller issues an audible alarm to the occupants of the dwelling and originates a call to the central monitoring service system via the telecommunications line. Upon receiving the breach notification, the central monitoring service system determines the type of breach, attempts to contact the dwelling occupants and alerts appropriate authorities of the emergency situation. 
     Normally, the telecommunications line interconnecting the security system to the central monitoring service system is the dwelling occupants&#39; telephone line. This line usually emanates and is visible from the exterior of the dwelling. It is this telecommunications line which delivers the security breach signal (i.e., in the form a call) to the central monitoring service system via telecommunications equipment. 
     To circumvent the security system from issuing a signal to the central monitoring service system, one need only render the telecommunications line inoperable. If the telecommunications line is severed, a breach signal from the security system will not be sent to the telecommunications equipment and hence, the central monitoring service system. As a result, the central monitoring service system remains unaware of an alarm situation at the secured premises and emergency authorities are not notified. 
     Although some security systems are equipped with a “line cut” option for alerting dwelling occupants of telecommunications line damage, there continues to be a need for efficiently and effectively alerting authorities when a telecommunications line interconnected to a security system is inoperable. 
     SUMMARY OF THE INVENTION 
     This need is addressed and a technological advance is achieved by the method and system of the present invention for alerting authorities whenever a telecommunications line interconnected to a security system becomes inoperable. More particularly, communication between a security system and a central monitoring system is maintained even if the telecommunications link interconnecting the systems is severed. 
     In a normal mode of operation, a security system is interconnected to telecommunications equipment via a wireline connection which serves the customer premises equipment of the secured premises. Upon detection of a severance or damage to the wireline connection, a wireless unit associated with the security system is activated to place a call to a central monitoring service system. Detection of the inoperability of the wireline connection is accomplished via the detection of abnormal electrical parameters associated with the wireline. The wireless call relays subscriber identification data and alerts the central monitoring system of a line cut emergency. The wireless unit may also be programmed to initiate calls to other telephone numbers (e.g., relatives, ambulance). The wireless unit serves as a backup system and is not activated unless the wireline connection is inoperable. 
     Advantageously, the central monitoring service system serving the subscriber&#39;s security system is alerted of an emergency situation even when the telecommunications line is inoperable. In other words, the security system is able to serve its intended purpose of alerting emergency authorities even when the telecommunications link interconnecting the system to the central monitoring service system is inoperable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a simplified block diagram of a security system at a secured premises; 
     FIG. 2 is a simplified block diagram of a telecommunications system which serves the security system equipment shown in FIG. 1; 
     FIG. 3 is a flow diagram illustrating the steps performed in the systems of FIGS. 1 and 2 in accordance with a first embodiment of the present invention; 
     FIG. 4 is a flow diagram illustrating the steps performed in the system of FIGS. 1 and 2 in accordance with a second embodiment of the present invention; 
     FIG. 5 is a flow diagram illustrating the steps performed in the systems of FIGS. 1 and 2 in accordance with a third embodiment of the present invention; and 
     FIG. 6 is a flow diagram illustrating the steps performed in the systems of FIGS. 1 and 2 in accordance with a fourth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows secured premises  100 , or a structure protected by a security system  102 . In this example, the security system protecting secured premises  100  comprises wireless unit  110 , customer premises equipment  120 , sensors  130 ,  132 ,  134  and  136  and controller  140 . 
     Controller  140  is interconnected to signal generator  142 , electrical parameter detector  144  and wireless interface  146  via links  141 ,  143  and  145 , respectively. Telephone line interface  148  is interconnected to controller  140  via link  149 . Link  151  drops from system  102  to telephone line  152  for interconnecting customer premises equipment  120  and the security system to the serving telecommunications equipment. In this example, the telecommunications equipment is a central office switch which provides the occupants of secured premises  100  regular telephone service. 
     Sensors  130 ,  132 ,  134  and  136  serve as security breach detectors for the security system. Sensor  130  is a motion and fire detector which communicates with system  102  via wireless link  131 . Sensor  132  is a window sensor hard wired to system  102  via link  133 . Sensor  134  is a door sensor hard wired to system  102  via link  135  and sensor  136  is another window sensor interconnected via wire  137  to the system. In the event of a breach (such as motion, heat or the unauthorized opening of windows  132 ,  136  or door  134 ), an alarm signal is sent from the sensor to system  102  via a designated link and received in controller  140 . 
     Cable modem  160  interconnected to security system controller  140  via link  161 . In this example, cable modem  160  serves a personal computer located on the premises and as a backup system for alerting the central monitoring service system in the event of inoperability of telecommunications line  152  (see FIG.  6 ). Link  162  interconnects the cable modem to a packet data network as described in FIG.  2 . 
     Also shown interconnected to security system  102  is wireless unit (telephone)  110 . Wireless unit  110  includes a processor for activating an emergency call protocol in response instructions received from controller  140  and memory for storing subscriber data and telephone numbers. Wireless unit  110  may also include an announcement circuit for issuing messages to called parties. 
     In response to receiving an alarm signal, controller  140  normally extends an alarm message to a central monitoring service system via traditional public-switched telecommunications equipment. In this example, the security breach message is sent by system  102  via telecommunications line  152  to a serving central office switch. Subsequently, the central office switch originates a call to the central monitoring service system. In the event of inoperability of telecommunications line  152 , however, the security system is disabled. In other words, no messages are transmitted from the security system to the central monitoring service system. 
     FIG. 2 is a simplified block diagram of telecommunications network  200 . Telecommunications network  200  comprises central office switch  210 , central security monitoring service system  250 , mobile switching center  260 , wireless base station  270  and packet data network  290 . 
     Central office switch  210  includes administrative module  212  interconnected to communications module  214  via link  213 . The communications module is connected to switch modules  216 ,  218  and  220  via links  217 ,  219  and  221 , respectively. Administrative module  212  handles billing, maintenance and test operations for all components within central office switch  210 . Communications module  214  relays messages among switch modules and between the switch modules and the administrative module. Each switch module includes a controller and a line interface for serving particular customer premises equipment. Each switch module controller includes memory for storing subscriber information identified by the subscriber&#39;s telecommunications line. In other embodiments, subscriber information is stored in an external database accessible by the switch module. The switch module controller also includes an algorithm for detecting electrical abnormalities for each of the lines which it serves. The data required for operation of the algorithm is retrieved from line interface equipment which measures electrical properties of a line using well known metallic loop testing procedures. 
     Switch module  216  includes controller  222  interconnected to line interface equipment  226  via link  223 . Line interface equipment  226  serves telephone line  152  which is interconnected to customer premises equipment  120 , as shown in FIG.  1 . Switch module  216  includes trunk interface  224  for interconnecting the switch module to central security monitoring system  215  via line or trunk  251 . In some embodiments trunk  251  may interconnect to the central monitoring system via other switches in the public switched telephone network. Switch module  218  includes controller  228  interconnected to line interface unit  230  via link  229 . Line interface unit  230  serves subscriber line  236  which is interconnected to customer premises equipment  240 . Switch module  220  includes controller  232  interconnected to line interface  234  via link  233 . Switch module  220  serves subscriber line  238  which is interconnected to customer premises equipment  242 . Although each switch module is shown serving only one interface of customer premises equipment, other embodiments include switch modules serving a plurality of customer premises equipment. 
     Also shown in mobile switching center  260  which is interconnected to switch module  220  via trunk  261 . Mobile switching center  260  serves wireless base station  270  via link  271 . 
     Central monitoring service system  250  includes controller  252  interconnected to communications interface  254 , database  256  and emergency interface  250  via links  255 ,  257  and  259 , respectively. Communications interface  254  enables central security monitoring system  250  to receive calls from traditional telephone switches or from a packet data network. Subscriber data is stored in database  256  and is used by controller  252  for retrieving address and subscriber profile information in response to emergency alert messages. Emergency interface  258  interconnects central security monitoring system  250  to networks operated by various emergency personnel, such as fire, police or hospitals. Also shown is packet data network  290  interconnected to central monitoring service system  250  via data link  164 . 
     FIG. 3 is a flow diagram illustrating the steps performed by the security system of FIG.  1  and the telecommunications network of FIG. 2 in accordance with the first embodiment of the present invention. The first embodiment of the present invention assumes a security system designed for continuous monitoring of a telephone line by telecommunications equipment. 
     The process begins in step  300  in which a serving telecommunications equipment (in this case, a central office switch) receives a system status signal from a telecommunications line interconnected to the system. In decision step  302 , the central office switch determines whether the next expected security system status signal has been received in accordance with a predetermined system status signal frequency. If the outcome of decision step  302  is a “YES” determination, the process continues to step  303 , in which the central office switch continues to monitor the telecommunications line for system status signals. If the outcome of decision step  302  is a “NO” determination, the process continues to step  304 , in which the central office switch accesses a subscriber line profile for an appropriate action plan. The profile is stored in the switch module controller and includes data identifying subscriber terms for reaction to a missed system status signal. For example, some subscribers may elect to allow multiple missed signals to occur before the central office switch takes action while other subscribers may prefer the central office switch to immediately originate a call to the central monitoring system upon the absence of a system status signal. 
     The process continues to step  306  in which it is assumed the central office switch must take some action in response to a missed signal. In this step, the central office switch originates a call to central security monitoring system  250 . More particularly, the central office switch extends a message (e.g., in the form a call issuing DTMF tones) to the central security monitoring system via line  251 . The message includes data identifying the subscriber line from which the status signal is absent. In step  308 , the central monitoring service system receives the alert call from the central office switch. A message including subscriber line data and the indication of a telecommunications line cut situation is downloaded by the switch to the central monitoring service system. In the preferred embodiment, the message issued by the switch is in dual tone multifrequency (DTMF) tone format. In step  310 , the central monitoring service system recognizes the indication of a line cut emergency associated with the subscriber line identified and alerts the appropriate authorities via the emergency interface  258 . 
     In an alternative embodiment, the central office switch monitors the telecommunications line for an electrical abnormality. Upon detection of any abnormal electrical parameter (such as changes in voltage, current or impedance) of a telecommunications line termination, the central office switch initiates a call to the central monitoring service system. 
     FIG. 4 is a flow diagram illustrating the steps performed in accordance with a second embodiment of the present invention. In this embodiment, a wireless call is placed by a security system wireless telephone to the central monitoring service system upon inoperability of a wireline telecommunications line. 
     The process begins in step  400 , in which the security system detects a damaged or inoperable telecommunications line. The line inoperability may be determined by a change in the electrical properties of the line recognized by electrical parameter detector  144 . In step  402 , the controller originates a wireless call to the central monitoring service system in response to the line inoperability. More particularly, the security system, as shown in FIG. 1, initiates a call to the central monitoring service system using wireless phone  110 . 
     Wireless phone  110  is programmed to dial a call and issue data when telecommunications line  152  is inoperable and cannot relay messages to the serving central office switch. In these situations, wireless phone  110  automatically places a call to central monitoring service system  250 . In this example, wireless phone  110  is served by wireless base station  270  which initiates a call to central monitoring service system  250  by extending a message to mobile switching center  260 . Mobile switching center  260  interconnects wireless phone  110  to central monitoring service system  250  via central office switch  210 . When the incoming call from wireless phone  110  is received in central monitoring service system  250 , the central monitoring system awaits DTMF tones which the wireless phone has been programmed to provide. These tones identify the subscriber served by the security system issuing the call and the indicate the presence of a telecommunications line abnormality or the status of sensor breaches at a secured premises. After completion of the call to the central monitoring service system, the wireless phone may be programmed to call other numbers (e.g., relatives, ambulance) and play a prerecorded message identifying an emergency and requesting help. In step  406 , the central monitoring service system obtains the subscriber identification information from the DTMF tones generated by the wireless phone and alerts the appropriate authorities via emergency interface  258 . 
     FIG. 5 is a flow diagram illustrating the steps performed in accordance with the third embodiment of the present invention. In this embodiment, it is assumed that the secured premises security system monitoring the telecommunications line is initialized to recognize electrical abnormalities of its serving telecommunications line and that the line is severed. 
     The process begins in step  500 , in which the security system operates in normal mode and monitors its serving telecommunications line. In this example, assume that the security system shown in FIG. 1 monitors telecommunications line  152  for its voltage level using electrical parameter detector  144 . In alternative embodiments, the telephone line may be monitored for its impedance level or some other electrical parameter. In decision step  502 , the security system controller determines whether the voltage level is abnormal. Typically, if telecommunications line  152  is severed, the voltage level will fall from an initial value (−39.5 to −57.5 volts) to zero volts. If the outcome of decision step  502  is a “NO” determination, the process returns to step  500 , in which the electrical parameter continues to be monitored. If the outcome of decision step  502  is a “YES” determination, the process continues to step  504 , in which controller  140  transmits an issue command to signal generator  142 . 
     In response to receiving this command, signal generator  142  issues a high frequency modulated signal on the damaged telecommunications line. The high frequency signal is approximately 1-5 MHz frequency hopping or with a cycle time fast enough to transmit approximately 100-150 feet. In this example, a first portion of the severed telephone line acts as a transmitter of a high frequency modulated signal and a second portion of the severed telecommunications line acts as a receiver of the high frequency modulated signal. Thus, in step  506 , the receiving portion of the severed telephone line receives the high frequency modulated signal from the transmitting portion of the telephone line and transmits this signal to the central office switch. 
     The process continues to step  508 , in which the central office switch receives the high frequency modulated signal and demodulates it to determine the identification of the subscriber line issuing the signal. This demodulation step occurs in the switch module using algorithms stored in the switch module controller. The demodulation algorithm identifies the subscriber line issuing the signal. The subscriber line identification may be used to access other subscriber data. In step  510 , the central office switch identifies the subscriber line issuing the high frequency modulated signal and originates a call to the central monitoring service system. In step  512 , the central monitoring service system receives the subscriber data via DTMF tones and alerts an appropriate emergency authority. 
     FIG. 6 is a flow diagram depicting the steps performed in the systems of FIGS. 1 and 2 in accordance with a fourth embodiment of the present invention. In this embodiment, it is assumed that a cable modem is interconnected to the security system on the secured premises and is initialized to respond to telecommunications line abnormality detection. 
     The process begins in step  600  in which the security system detects the line abnormality. This line abnormality may be detected in accordance with the above-identified detection implementation. In step  602 , the security system issues an alert message to a cable modem interconnected to the security system controller. In the examples of FIGS. 1 and 2, security system controller  140  issues an alert signal to cable modem  160  via link  161 . In step  604 , the cable modem receives the alert message and issues a line abnormality message to the central monitoring service system via link  162  which interconnects the cable modem to a packet data network. In this example, the alert message arrives in packet data network  190  via link  162  and is forwarded to central monitoring service system  250  via data link  164 . 
     The process continues to step  606  in which the central monitoring service system receives the line breach message or emergency identification message in its communications interface  254  and identifies the subscriber line associated with the line breach via the network address information transmitted by the packet data network. In step  608 , the central monitoring service system alerts appropriate authorities of the line abnormality after accessing the subscriber profile in database  256 . In alternative embodiments the cable modem may also be interconnected to a video camera or microphone located on the secured premises so that a video or audio feed to the central monitoring service system may be provided via the packet data network. 
     Advantageously, in each of the above-described embodiments, a security system operates even when its telecommunications connection is severed. In other words, subscribers of security system services are assured that even if their telephone line is severed, the central monitoring service system will be notified of the abnormality and can respond accordingly. 
     Although this invention has been described with respect to various illustrative embodiments, numerous other arrangements may be devised without departing from the scope of the present invention. For example, any system in which interconnection to telecommunications equipment is required can benefit from the present invention which allows an emergency signal to be sent in event of inoperability of the telephone line.