Telephonic communications – Emergency or alarm communications – Central office responsive to emergency call or alarm
Reexamination Certificate
2000-05-26
2001-12-04
Woo, Stella (Department: 2643)
Telephonic communications
Emergency or alarm communications
Central office responsive to emergency call or alarm
C379S047000, C379S037000
Reexamination Certificate
active
06327342
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an emergency 911 call answering systems, and more particularly relates to a computer-based system that monitors the operation of an emergency 911 call answering system and switches any in-progress or incoming calls to alternative answering devices.
BACKGROUND OF THE INVENTION
Many communities operate emergency 911 call answering systems, also called “E911 call answering systems” or public safety answering position (PSAP) equipment. These systems are typically computer-controlled telephone switching systems that receive 911 calls at a central emergency services dispatching center and connect the calls to emergency services dispatchers via the E911 trunk lines. The E911 calls are routed to the dispatching center by telephone company central offices, and are answered by dispatchers who determine the caller's physical location by computer assistance, ascertain the type and severity of the caller's needs, and dispatch appropriate emergency services.
The computer system is typically used to receive automatic number identification (“ANI,” also known as “caller ID” information) from the telephone call, use the caller ID to index a computer database to determine the calling party's location (address), and display the calling party's location on a graphical display. These computer-assisted operations facilitate the assignment of an appropriate emergency service vehicle and personnel.
Many of these E911 call-answering systems operate under control of a multi-threaded multi-tasking operating system (MTOS). However, these MTOSs have a known propensity to fail or “lock up” under unknown conditions. If the failure occurs during the handling of an emergency call, the dispatcher can lose communication with the distressed calling party, who may be in a life-threatening situation. It goes without saying that such a failure is extremely undesirable. Although the computer-based emergency 911 system can usually be rebooted, valuable time has been lost. Even if the situation is not life threatening and the calling party calls back, the failure of the system is disruptive.
Accordingly, there is a need for a system to detect the possible failure of a computer-operated E911 call answering system. There is a further need in the art for a system that can keep emergency 911 calls from being dropped during a failure of the underlying computer system of the emergency 911 call answering system.
SUMMARY OF THE INVENTION
The present invention meets the above-described need by providing an E911 backup system that bridges and monitors standard analog E911 trunks in an emergency 911 call answering system (“E911 call answering system”), also known as public safety answering position (PSAP) equipment. The E911 backup system takes control of the E911 trunks in the event of primary PSAP equipment failure. This is accomplished by monitoring and selectively acting upon a series of alarm signals. Upon detecting one or more of the alarm signals, the E911 backup systems takes over every E911 trunk line, passing any new or in progress calls to a standard telephone handset by activating the standard telephone's ringer and patching the call through to the phone when answered.
Once the E911 backup system ceases to detect an alarm signal, control of the E911 trunk lines are restored to the E911 call answering system. The control of the E911 trunks will not, however, pass back to the E911 call answering system if a call is in progress. Control of the E911 trunks will pass over to the E911 call answering system only when no alarm signals are detected and no calls are present on the E911 trunks.
While the E911 backup system is active, incoming automatic number identification (ANI) information will be displayed on an alphanumeric display. Also, the E911 backup system will print call log information to an attached printer. This log information consists of trunk seizure time, answer time, and call termination time, the party that terminated the call and ANI information if available.
When a call comes in to an E911 call answering system, the originating equipment (CO or Tandem) will draw line current from the trunk. When the E911 equipment senses this, it acknowledges by sending a momentary battery reversal (wink) to the originating equipment. After the wink, the originating equipment will send the ANI information using multi-frequency (MF) signaling. After the ANI information is received, the call can be answered.
Generally described, the E911 backup system bridges and monitors an E911 call answering system that is connected to a series of standard analog E911 trunk lines. The E911 backup system includes a control unit that continually monitors a series of alarm signals generated by the E911 call answering system. If the switching unit detects one or more alarms signals, the control unit transmits a control signal to disable the E911 call answering system and the causes any new or in-progress calls carried by the 911 trunk lines to a be routed to a number of standard telephone handsets. Inputs to the E911 backup system, which include the alarm signal, the power supply and the E911 trunks enter the E911 backup system through a single input port. The outputs of the E911 backup system, which include the E911 trunks are output through an output port, such as a standard RJ-11 telephone jack, to a series of standard telephone handsets.
The E911 backup system also includes a display unit displaying information regarding the status of the control unit and the E911 trunks. For example, incoming calls on the E 911 trunk typically contain an ANI, or caller ID information. The display unit can display the ANI of the incoming call, thereby allowing an operator to determine the calling party's telephone number in the event of an E911 call answering system failure. Although, the operator may not be able to immediately determine the location of the calling party, the operator may be able to use the calling party's phone number to manually search a database to determine the caller's location. The display unit can also display status messages of any diagnostic test that the E911 backup system performs or the operational status of the E911 call answering system. This allows the operators of an E911 call answering system to quickly determine whether there is a problem with the E911 backup system or the E911 call answering system by simply checking the display unit.
The display unit also contains a series of light emitting diodes (LEDs) to further indicate the status of the E911 backup systems. Each E911 trunk connected to the E911 backup systems has a pair of LEDs associated with it to indicate whether it is in use when the incoming calls have been routed to the E911 backup system. For example, one LED will be on when the E911 trunk is idle, or when there is no incoming call on the line. Similarly, the other LED will be on when the E911 trunk is active, or contains an incoming call. Therefore, using both an alphanumeric display and a series of LED pairs, an operator is able to assess the status of both the E911 backup system and the E911 trunks quickly and easily. The E911 backup system also contains a data bus, which carries both the data and control signals between the control unit, the switching unit and the display unit.
More specifically described, the invention is directed towards the E911 backup system for an E911 call answering system in which the control unit includes a central processing unit (CPU) and several memory storage devices to control the operation of the backup unit. A first memory storage device, such as an erasable programmable read-only memory (EPROM), may store a computer application program to initialize the E911 backup system. Each time the E911 backup system is turned on the initialization computer program is loaded into the CPU via the data bus and activates or “boots up” the E911 backup systems. In addition to initializing the E911 backup system, the initialization code also performs a series of diagnostic test to ensure that the E9
Machell Simon J. G.
Mobley Matthew Stephen
Ramakrishnaiah Melur
Stockton Kilpatrick
Woo Stella
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