E911 backup system for emergency 911 call answering systems

• US 6,327,342 B1
• Filed: 05/26/2000
• Issued: 12/04/2001
• Est. Priority Date: 05/28/1999
• Status: Expired due to Fees

• Current Assignee: Baker Integrated Technologies, LLC
• Original Assignee: Baker Integrated Technologies, LLC
• Inventors: Mobley, Matthew Stephen, Machell, Simon J. G.
• Primary Examiner(s): Woo, Stella
• Assistant Examiner(s): Ramakrishnaiah, Melur
• Application Number:
  US09/579,742
• Time in Patent Office: 557 Days
• Field of Search: 379/45, 379/46, 379/47, 379/48, 379/49, 379/37, 379/38, 379/39, 379/40, 379/41, 379/42, 379/43, 379/44, 379/265, 379/266
• US Class Current: 379/45
• CPC Class Codes: H04M 2242/04 for emergency applications
• CPC Class Codes: H04M 3/12 Marking faulty circuits "busy"; Enabling equipment to disengage itself from faulty circuits ; Using redundant circuits; Response of a circuit, apparatus or system to an error
• CPC Class Codes: H04M 3/22 Arrangements for supervision, monitoring or testing
• CPC Class Codes: H04M 3/5116 for emergency applications

Abstract

The present invention is an E911 backup system that bridges and monitors standard analog E911 trunks in an emergency 911 answering system (“E911”), also know as a public safety answering position (PSAP) equipment. The E911 backup system has the ability to take control of these trunks in the event of primary PSAP equipment failure. This is accomplished by monitoring and selectively acting upon a series of alarm signals. The alarm signals include: a watchdog signal from the E911 call answering system; a batter monitor to detect the presence of a voltage on the E911 analog trunk; a wink watch signal to monitor whether the primary systems transmits a wink signal; and an answer alarm signal that detects the E911 call answering systems failure to answer an incoming call within a specified period of time. Upon detecting one or more of the selected alarm signals, an E911 backup system assumes control of the E911 trunk, passing any new or in progress calls to a standard telephone handset by operating the phone'"'"'s ringer and patching the call through to the telephone when answered.

Claims

1. An apparatus for providing a back-up service for an E911 call answering system, wherein the E911 call answering system comprises a plurality of E911 trunk lines operable for carrying a plurality of incoming telephone calls, comprising:

a control unit operative for monitoring a plurality alarm signals generated by the 911 system;

a switching circuit operative for routing the incoming telephone calls carried by the plurality of 911 trunk lines to a plurality of telephones when the switching unit detects at least one of the plurality of alarm signals;

an input port operative for receiving the incoming telephone calls carried is by the plurality of trunk lines, the alarm signals generated by the E911 backup system, and a power signal;

an output port connected to the switching circuit plurality operative for transmitting the telephonic data from the trunk lines to at least one of a plurality of telephone handsets; and

a data bus operable for carrying information between the control unit, the switching unit and the display circuit.

2. The apparatus of claim 1 further comprising:

a display circuit operative for displaying information regarding the status of switching circuit;

a serial port connected to the data bus operative for transmitting and receiving a plurality of control data;

a printer port operative for transmitting a plurality of status information to a printer; and

a power supply operative for receiving an input voltage and supplying a plurality of output voltages.

3. The apparatus of claim 2, wherein the control unit comprises:

a central processing unit;

a first memory storage device connected to the central processing unit operative for storing an initialization computer program;

a second memory storage device connected to the central processing unit operative for storing a computer application program comprising a plurality of subprograms; and

a third memory storage device operative for storing the information associated with the incoming telephone calls.

4. The apparatus of claim 3, wherein the first memory storage device is an erasable programmable read-only memory.

5. The apparatus of claim 3, wherein the initialization computer code is loaded into the central processing unit from the first memory storage device when power is applied to the E911 backup system.

6. The apparatus of claim 5, wherein the initialization computer code comprises computer-readable instructions for performing a set of diagnostic tests on the control unit, the switching unit and on the display circuit.

7. The apparatus of claim 6, wherein the initialization computer code further comprises computer-readable instructions for downloading the computer application program stored in the second memory.

8. The apparatus of claim 3, wherein the second memory storage device comprises a random access memory.

9. The apparatus of claim 3, wherein the computer application program comprises a plurality of operating modes.

10. The apparatus of claim 9, wherein the control unit further comprises a switching circuit operative for enabling at least one of the plurality of operating modes contained in the computer application program.

11. The apparatus of claim 2, wherein the display circuit comprises:

a first display operative for displaying a plurality of alphanumeric messages generated by the control unit; and

a second display comprising;

a first group of lights operative to indicate the polarity of each trunk line connected to the input port, and

a second group of light operative to indicate whether the E911 backup system is turned on.

12. The apparatus of claim 9, wherein the plurality of operating modes comprise a diagnostics mode, a random access memory update/backup disable mode, a take over on battery loss mode, take over on no wink/no answer mode, a take over on watchdog signal mode, a no function mode, an unconditional take-over mode, and a 20 digit ANI display mode.

13. The apparatus of claim 2, wherein the switching unit comprises:

a plurality of 911 interface circuits, wherein each 911 -interface circuit is associated with at least one of the 911 trunk lines and is operative for monitoring the plurality of incoming telephone calls from the plurality of 911 trunk lines;

a plurality of plain old telephone interfaces, wherein each plain old telephone interface is associated with at least one of the telephone handsets and is operative to transmit the incoming telephone calls to at least one telephone handset; and

a plurality of opto-isolators, wherein each opto-isolator is associated with at least one of the trunk lines and is operative to monitor a wink signal generated by each trunk line and generate at least one alarm signal if at least one wink signal is not detected.

14. The apparatus of claim 13, wherein at least one of the alarm signals is a watchdog signal.

15. The apparatus of claim 13, wherein at least one of the alarm signal is an absence of a voltage on at least one of the trunk lines.

16. The apparatus of claim 13, wherein at least one of the alarm signals is a watchdog signal.

17. An apparatus for backing up an E911 call answering system, wherein the E911 call answering system comprises a plurality of E911 trunk lines operable for carrying a plurality of incoming telephone calls, comprising:

a control unit operative for monitoring a plurality alarm signals generated by the E911 call answering system;

a switching circuit operative for routing the incoming telephone calls carried by the plurality of E911 trunk lines to a plurality of telephones when the switching unit detects at least one of the plurality of alarm signals;

an input port operative for receiving the incoming telephone calls carried by the plurality of E911 trunk lines, the alarm signals generated by the E911 backup system, and a power signal;

an output port connected to the switching circuit operative for transmitting the telephonic data from the trunk lines to at least one of a plurality of telephone handsets;

a data bus operable for carrying information between the control unit, the switching unit and the display circuit;

a display unit operative for displaying information regarding the status of switching circuit;

a serial port connected to the data bus operative for transmitting and receiving a plurality of control data;

a printer port operative for transmitting a plurality of status information to a printer; and

a power supply operative for receiving an input voltage and supplying a plurality of output voltages.

18. The apparatus of claim 17, wherein at least one of the plurality of alarm signals comprise a watchdog signal from the E911 call answering system.

19. The apparatus of claim 17, wherein at least one of the plurality of alarm signals comprise a no battery on the E911 trunk signal.

20. The apparatus of claim 17, wherein at least one of the plurality of alarm signals comprises a wink watch signal.

21. The apparatus of claim 17, wherein at least one of the plurality of alarm signals comprises a no answer signal.

22. The apparatus of claim 17, wherein the information carried by the E911 trunk lines comprises an automatic number identification.

23. The apparatus of claim 17, wherein the control unit comprises:

a central processing unit;

an erasable programmable read-only memory storage device connected to the central processing unit operative for storing an initialization computer program;

a flash random access memory storage device connected to the central processing unit operative for storing a computer application program comprising a plurality of subprograms; and

a random access memory storage device operative for storing information associated with the incoming telephone calls.

24. The apparatus of claim 17, wherein the switching unit comprises:

a plurality of 911 interface circuits, wherein each 911 -interface circuit is associated with at least one of the 911 trunk lines and is operative for monitoring the plurality of incoming telephone calls from the plurality of 911 trunk lines;

a plurality of plain old telephone interfaces, wherein each plain old telephone interface is associated with at least one of the telephone handsets and is operative to transmit the incoming telephone calls to at least one telephone handset; and

a plurality of opto-isolators, wherein each opto-isolator is associated with at least one of the E911 trunk lines and is operative to monitor a wink signal generated by each trunk line and generate at least one alarm signal if at least one wink signal is not detected.

25. A method of backing up a 911 call answering system using E911 backup system connected to the 911 call answering system in parallel across a plurality of trunk lines connected to the 911 call answering system, comprising the steps of:

monitoring a plurality of alarm signals between the E911 backup system band the 911 call answering system;

detecting at least one of the plurality of alarm signals;

transmitting a control signal from the E911 backup system to the 911 call answering system, the control signal operative to disable the 911 call answering system in response to detecting at least one of the plurality of alarm signals;

routing the incoming telephone calls on at least one of the trunk lines to the E911 backup system; and

routing the incoming telephone calls from the E911 backup system to a plurality of telephone handsets.

26. The method of claim 25, further comprising:

monitoring the plurality of trunk lines to determine whether the alarm signal has ended;

displaying a message on a display device to indicate that the alarm signal has ended in response to determining that the alarm signal has ended;

monitoring the plurality of trunk lines to determine whether information is being transmitted on at least one of the trunk lines from a control office; and

transmitting a second control signal to the 911 call answering system to enable the 911 call answering system to receive the plurality of information transmitted on the plurality of trunk lines in response to determining that no information is transmitted on any one of the trunk lines.

27. The method of claim 26, wherein at least one alarm signal is a watchdog signal.

28. The method of claim 26, wherein at least one of the alarm signal is generated by the absence of a voltage on at least one of the trunk lines.

29. The method of claim 26, wherein at least one of the alarm signals is generated by the absence of a wink signal.

30. The method of claim 26, wherein at least one of the alarm signals is a watchdog signal.