SYSTEM AND METHOD FOR FACILITATING WIRELESS CALL CONNECTIONS IN EMERGENCY SITUATIONS

Abstract: A system and method (10) for facilitating wireless call connection to an emergency service. The system includes a mechanism for attempting a call to an emergency call center via a wireless service provider. The system monitors the availability of service (14) provided by the wireless service provider and automatically completes the call (16) if the service is or becomes available. In a specific embodiment, the system includes software for searching for a wireless service (18) through which an emergency call may be placed. The system repeatedly dials the phone number of the emergency call center until the call is completed. In the specific embodiment, the software for repeatedly dialing 911 includes silent-redial (30) software.

Description: SYSTEM AND METHOD FOR FACILITATING WIRELESS CALL CONNECTIONS IN EMERGENCY SITUATIONS BACKGROUND OF THE INVENTION I. Field of Invention: This invention relates to wireless communications systems. Specifically, the present invention relates to systems for facilitating emergency call connection in cellular telecommunications systems. II. Description of the Related Art: As cellular telephone usage has increased, reliance upon cellular telephones to obtain emergency service has increased as well. Typically, a user of a wireless phone dials 911 to reach an emergency call center. If the phone is in a spotty coverage area such as an area characterized by deep fades, the user must continue dialing 911 until the phone establishes a connection. The need to continually redial 911 to make a connection is undesirable in an emergency situation where time is of paramount importance and the user may be injured or impaired. Accordingly, the Federal Communications Commission (FCC) recently implemented legislation requiring wireless service providers to implement methods to facilitate cellular telephone emergency call connections. Hence, a need exists in the art for an improved system and method for facilitating wireless call connections in emergency situations. SUMMARY OF THE INVENTION The need in the art is addressed by the system for facilitating a wireless call connection to an emergency call center of the present invention. In the illustrative embodiment, the inventive system is adapted for use with a cellular telephone and includes a mechanism for attempting a call to an emergency call center via a wireless service provider. The system monitors the availability of service provided by the wireless service provider and automatically completes the call if the service is or becomes available. In a specific embodiment, the system includes software for searching for a wireless service through which an emergency call may be placed. The system repeatedly dials the phone number of the emergency call center until the call is completed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram of a method for facilitating a wireless call connection to an emergency call center of the present invention. FIG. 2 is a more detailed diagram of the method of FIG. 1. FIG. 3 is a diagram of a cellular telephone constructed in accordance with the teachings of the present invention for implementing the method of FIG. 1. FIG. 4 is a diagram showing various states of the display screen of the cellular telephone of FIG. 3 as the cellular telephone cycles through various states in accordance with the method of FIG. 1. DESCRIPTION OF THE INVENTION While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. FIG. 1 is a flow diagram of the method 10 for facilitating a wireless call connection to an emergency call center of the present invention. In the preferred embodiment, the unique method 10 is implemented in software running on the cellular telephone as is discussed more fully below. Initially, at step 11, a user of a cellular telephone or wireless phone adapted for use with the present invention, as is discussed more fully below, dials '911' and presses 'Enter' or 'Send" on the cellular telephone. Next, at step 12, the speaker volume of the cellular telephone is set to maximum. Subsequently, in a service-checking step 14, the cellular telephone checks for any available wireless service provided by a wireless service provider. If service is found, control is passed to a call-originating step 16 where the cellular telephone automatically dials 911 and attempts to connect to an emergency call center. If no wireless service is found in the service-checking step 14, control is passed to a service-searching step 18 where the cellular telephone continues to search for service until service is found, i.e., acquired. The cellular telephone searches frequencies, i.e., channels in a preferred roaming list (PRL) stored in memory in the cellular telephone. If a channel contains a known code division multiple access (CDMA) signal, the telephone assumes that the service was successfully acquired. Once wireless service is acquired in the service-searching step 18, control is passed to the call-originating step 16. If in the call-originating step 16 the emergency 911 call fails, i.e., is dropped or is never established, control is passed back to the service-checking step 14 forming a loop comprising the service- checking step 14, the service-searching step 18, and the call-originating step 16. The loop is exited when the method 10 is complete. The method is complete when service is acquired, the battery on the cellular telephone dies, or the user cancels the method 10. The method 10 is cancelled by turning off the cellular telephone or by pressing an END key on the cellular telephone. If after the method 10 is complete and an emergency call is connecting or originating and subsequently the connecting or originating call fades or is dropped, the cellular telephone automatically restarts the method 10 and control is passed to service-checking step 14. The novel design of the present invention may help a user in an emergency situation save valuable time and attention that may otherwise be required to obtain emergency service through the cellular telephone. FIG. 2 is a more detailed diagram of the method 10 of FIG. 1. The service- checking step 18 includes a callback-mode-checking step 20, a looking-for-service step 22, a continuing-emergency-search step 24 and an emergency-service-lost step 26. The call-originating step 16 includes a calling-emergency-911 step 28 and a silent redial step 30. After the volume-setting step 12, the service-checking step 14 determines if service is currently available. If no service is currently available, control is passed to the callback-mode-checking step 20 in the service-searching step 18. The callback-mode-checking step 20 checks if the cellular telephone is currently in a callback mode. When in a callback mode, the cellular telephone will automatically answer an incoming call from an emergency call center if the call is unanswered after a predetermined number of rings. A more detailed discussion pertaining to the emergency callback mode is provided in co-pending U.S. Patent Application serial no. 09/246,467 filed on February 9, 1999, entitled SYSTEM AND METHOD FOR AUTOMATICALLY ANSWERING INCOMING EMERGENCY CALLS TO A WIRELESS PHONE, the teachings of which are incorporated herein by reference. If the cellular telephone is in a callback mode, control is passed to the emergency-service-lost step 26 in the service-searching step 18 where the cellular telephone continues to search for a wireless service on the same system on which the cellular telephone successfully originated an emergency call that was dropped before the call entered a conversation state. In the emergency-service-lost step 26, the cellular telephone displays a message on a cellular telephone screen, as discussed more fully below, specifying that emergency service is lost and that the cellular telephone is continuing to search for emergency service. The emergency- service-lost step 26 continues until wireless service is acquired or until the step 26 is cancelled by the user of the cellular telephone or cancelled due to lack of cellular telephone battery power. If service is acquired in the emergency-service-lost step 26, control is passed to the calling-emergency-911 step 28 in the call-originating step 16. If the cellular telephone is not in a callback mode as determined in the callback-mode-checking step 20, control is passed to the looking-for-service step 22 where the cellular telephone continues to search for any possible wireless service through which to connect to an emergency call center. In the looking-for- service step 22, a message is displayed on the cellular telephone screen informing the user that the cellular telephone is currently looking for emergency service. If service is not acquired within a 1 minute time period, control is passed to the continuing-emergency-search step 24. In the continuing-emergency-search step 24, the cellular telephone continues to search for emergency service and displays a message on the cellular telephone screen informing the user that the cellular telephone is continuing searching for emergency service. If within 7 seconds wireless service is not acquired in the continuing-emergency-search step 24, control is passed back to the looking-for-service step 22. If in the looking-for- service step 22 or the continuing-emergency-search step 24 or the emergency- service-lost step 26 service is acquired, control is passed to the calling-emergency- 911 step 28 in the call-originating step 16. In the calling-emergency-911 step 28, the cellular telephone displays, on the cellular telephone screen, a message informing the user that the cellular telephone is currently calling 911. Control is immediately passed to the silent-redial step 30 where the cellular telephone automatically dials 911. If the 911 call is successfully established, i.e., completed, the method 10 is complete. Otherwise, control is passed back to the service-checking step 14. The present invention provides an efficient method through which a wireless phone may redial an emergency number without user intervention in unreliable service coverage areas. This ensures that the wireless phone maximizes its abilities to obtain emergency service even in situations in which the user of the phone becomes unconscious. FIG. 3 is a diagram of a cellular telephone 50 constructed in accordance with the teachings of the present invention for implementing the method 10 of FIG. 1. The cellular telephone 50 includes an antenna 52 connected to a duplexer 54. The duplexer 54 is connected to transceiver circuitry 56 and the transceiver circuitry 56 is connected to a computer 58. The computer 58 is connected to a data interface adapter 60, voice encoding and decoding circuitry 62, a keypad 64, and a screen 66. The voice encoding and decoding circuitry 62 is connected to a microphone 68 and a speaker 70. In operation, the antenna 52 transmits and receives signals via the duplexer 54. The duplexer 54 facilitates sharing of resources of the antenna 52 between transmit and receive functions. The transceiver 56 includes circuitry for transmitting signals such as encoded voice signals or service negotiation signals via the antenna 52 and duplexer 54. The transceiver 56 also includes receive circuitry for receiving signals such as service negotiation messages or encoded voice signals via another phone, base station, or mobile switching center. The transceiver 56 also includes downconversion circuitry required to convert receive signals to digital baseband signals in preparation for processing via the computer 58. In addition, the transceiver circuitry 56 includes upconversion circuitry required to convert transmit signals from digital baseband signals to radio frequency signals in preparation for transmission via the antenna 52. A user may initiate a call by dialing a number via the keypad 64. The computer 58 negotiates a service connection with an available wireless service provider via the transceiver circuitry 56, the duplexer 54, and the antenna 52. When service is established, the user's voice is input to the microphone 68, encoded by the voice encoding and decoding circuitry 62 and transmitted via the computer 58, transceiver circuitry 56, duplexer 54, and the antenna 52. Similarly, received voice messages are decoded by the voice encoding and decoding circuitry 62 and output as voice via the speaker 70. The user of the cellular telephone 50 may dial an emergency service such as 911 via the keypad 64. Software designed in accordance with the method of the present invention and running on the computer 58 determines that the call is an emergency call and begins the method of the present invention. Software to implement the method of the present invention on the computer 58 may be developed by one of ordinary skill in the art without departing from the scope of the present teachings and without undue experimentation. The software may include routines for each step in the method of FIG. 1. For example, the call- originating step 16 may employ silent-redial software well known in the art. The computer displays messages on the screen 66 such as "Searching for emergency service...." in accordance with the method of FIG. 1. The data interface connection 60 allows software running on the computer 58 to be upgraded and/or changed. In the present specific embodiment, the computer 58 includes a 186 processor. Emergency call attempts are permitted at any time including when a cellular telephone 50 is locked or when no service is available. If an emergency call attempt is made when no service is available then the cellular telephone 50 will continue to scan for service until either the search is cancelled (by pressing END), the call is originated, the telephone battery expires (if external power is not present), or when the cellular telephone 50 is turned off. Only certain numbers that are designated as true emergency numbers force the cellular telephone 50 into an emergency call mode in where the method of FIG. 1 is activated. The certain numbers are edited through the PST (Product Support Tool) or through software hard-coding. Emergency phone numbers such as 911 are not universal and may vary from country to country. A wireless carrier may provide special entries in an electronic phonebook specifying other emergency numbers. When a user dials a number or code associated with an emergency number in the phone book, emergency call processing is initiated in accordance with the teachings of the present invention. See for example, co-pending U.S. Patent Application Serial No. 09/246,395 filed on February 9, 1999, entitled SPECIAL PHONEBOOK ENTRIES, assigned to the Assignee of the present invention and incorporated herein by reference. Software for implementing the phone book may run on the computer 58. For clarity, additional circuitry such as clocking circuitry and power supplies are not shown in the cellular telephone 50, but those ordinarily skilled in the art will know where and how to include the requisite additional circuitry. FIG. 4 is a diagram showing various states of the display screen 66 of the cellular telephone 50 of FIG. 3 as the cellular telephone 50 cycles through various states 80 in accordance with the method of FIG. 1. With reference to Figs. 3 and 4, when the user dials 911, the number (911) is displayed in a first state 82 and the cellular telephone 50 enters the emergency call mode. If wireless service is lost and/or a search for wireless service is necessary, the display screen 66 enters a second state 84 and displays the following message: "Looking for emergency service...." The message has animated periods. In addition, the elapsed time is displayed on the display screen 66 indicating the time that has elapsed from the initial emergency call attempt. If a search is in progress and a system, i.e., a wireless service is not acquired after one minute, then the display screen 66 enters a third state 86 and displays the following status message: "Continuing Emergency Search..." The status message reoccurs every minute during searching. The message is displayed for 7 seconds and backlighting features of the display screen 66 are activated for the 7 second period. If wireless service is available or is acquired, the display screen 66 enters a fourth state 88 and displays the following message: " Calling... Emergency." Upon acquisition of a wireless service, two beep tones are emitted through a ringer (not shown) to obtain maximum effect, and call origination activity (with an "Emergency nametag") occurs from the time of call acquisition until the end of the call. If the user of the cellular telephone 50 originates an emergency call and the emergency number is not stored in a user phonebook under a user defined name, the phone automatically attaches an emergency name tag. Specifically, the term "Emergency" is displayed, informing the user that an emergency call is taking place. If the cellular telephone 50 acquires a non-preferred system for wireless service for placing an emergency call, then a roaming indicator on the display screen 66 is activated and flashes for emergency calls. This occurs when wireless service is not already available at the time of the call attempt and non-standard searching and acquisition is required to acquire the wireless service. If a silent redial fails, then a beep tone is emitted (and may be emitted through the speaker 70); the keypad 64 is back-lit; and the following message is displayed: "Looking for Emergency Service..." Hence, if a cellular telephone user attempts an emergency call such as 911 in the United States, the cellular telephone enters a special emergency 911 mode. When in the emergency 911 mode, if the phone 50 is not able to connect with an emergency call center via a wireless service, the cellular telephone 50 notifies the user that it is searching for emergency service. If the cellular telephone 50 obtains wireless service it automatically attempts to make the call, i.e., attempts call origination. If the call origination is unsuccessful and the cellular telephone 50 currently has acquired a wireless service, the cellular telephone 50 automatically re-attempts call origination. If call origination fails and the cellular telephone 50 has not acquired a wireless service, the cellular telephone 50 notifies the user that the wireless service is lost and the phone 50 repeats the above steps until emergency call origination is successful or the call attempt is ended by the user, or the automatic retry is otherwise terminated. Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications and embodiments within the scope thereof. It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention. WHAT IS CLAIMED IS:

Claims: CLAIMS 1. A system for facilitating a wireless call connection to an emergency call center comprising: first means for attempting a call to an emergency call center via a wireless service provider; second means for monitoring the availability of service provided by said wireless service provider to determine if service is available from said wireless service provider; and third means for completing said call if said service is available as determined by said second means. 2. The system of Claim 1 wherein said first means includes a cellular telephone. 3. The system of Claim 1 wherein said second means includes software for searching for a wireless service through which an emergency call through said wireless service provider may be placed. 4. The system of Claim 1 wherein said third means includes software for repeatedly dialing a phone number of said emergency call center until said call is completed or established when said wireless service is available as determined via said second means. 5. The system of Claim 4 wherein said phone number is 911. 6. The system of Claim 4 wherein said software includes silent-redial software. 7. The system of Claim 1 wherein said second and third means are implemented via software running on a computer included in said first means 8. The system of Claim 7 wherein said computer is in communication with at data interface cable and includes a 186 processor. 9. A system for facilitating a wireless call connection to an emergency service comprising: first means for attempting a call to an emergency call center via a wireless service provider; second means for monitoring service availability provided by said wireless service provider to determine a time period in which to activate said first means; and third means for activating said first means in response to said time period provided by said second means. 10. The system of Claim 9 further including fourth means for selectively halting operation of said second and third means in response to a predetermined user input to said first means. 11. The system of Claim 10 wherein said time period is the time period between when a user of said wireless phone attempts to place said call via said first means and when said user cancels the operation of said first means via said fourth means. 12. The system of Claim 10 wherein said first means is a cellular telephone. 13. The system of Claim 12 wherein said second means and said third means include silent redial software running on a computer included in said cellular telephone. 14. A method for facilitating wireless call connection to an emergency service comprising the steps of: first attempting a call to an emergency call center via a wireless service provider; monitoring wireless service availability to determine if service is available from said wireless service provider; and completing said call if said service is available as determined in said step of monitoring.

Inventors: NEW WEN JING, SIU TA-YAN, NEW, WEN, JING, SIU, TA-YAN
Applicants: QUALCOMM INC, QUALCOMM INCORPORATED
Application year: 2000
Main classification: H04Q7
IPC codes: H04M3, H04M11, H04W4