Abstract:
The present invention relates to a system and method of reliably determining that a cellular phone call has been dropped and then automatically reconnect the call. The invention is applicable for use in telephone systems that have off-premises call hunting algorithms and thereby use separate telephony channels for the inbound and outbound legs of a call.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a system and method of automatically reconnecting a cellular phone call. The invention is applicable for use in telephone systems that have off-premises call hunting algorithms and thereby use separate telephony channels for the inbound and outbound legs of a call.  
       BACKGROUND OF THE INVENTION  
       [0002]     A not too uncommon problem with cellular phone service is that calls are dropped during a conversation between the calling and called parties. Prior art systems exist, such as Avaya&#39;s Digital HotDesk system, (described in the attached Appendix and incorporated herein by reference), that will attempt to reconnect dropped calls for calls that are being controlled by the subscriber&#39;s telephony server where this server provides a find-me/follow me feature. With such find me/follow me systems, a call placed to a subscriber&#39;s normal phone number is routed to an auxiliary number. That is, by way of example, a call placed to called subscriber&#39;s office phone is rerouted to his cell-phone. With the prior art reconnect system, the outbound call (between the server and the called party&#39;s cell phone) is monitored in an attempt to identify the occurrence of a cellular cut-off, that is, the loss of the call connection due to network coverage limitations. Typically, this is done by waiting a specified period of time, after the called party has cleared down, while the calling party is still holding onto the call. If the time period is exceeded, the system will automatically place a call back to the called party, and provide a voice message to the calling party (e.g., “Please remain on the line while we attempt to reconnect your call”). If the called party&#39;s cellular phone is available and he answers the call, then the calling party and called party are reconnected. Typically such a system will try to reconnect to the called party for a given time period, and if unsuccessful during this period it will then place the calling party into the called party mailbox.  
         [0003]     Such a reconnect system, when working properly, has various advantages to both the called and calling parties. From the calling party&#39;s prospective, they do not have to redial in the event of a call being lost due to limitations in cellular coverage—they will either be reconnected to the called party or they will be offered a chance to leave a message. The called party knows that the call will be reestablished and waits for this to happen. If it is not, he can later check for a message. If used correctly, such a system eliminates the possible reaction of both parties trying to place a call to each other simultaneously and unavoidably missing each other due to call collision or limited call appearances on their telephony devices.  
         [0004]     These prior art reconnect systems suffer from a serious deficiency in that the identification of a cellular cut-off is not always done properly. Such false alarms cause reconnection for calls intended to be terminated. Moreover, such systems encounter problems when a mobile subscriber is involved with a conference call.  
         [0005]     The present invention overcomes these problems in the prior art by being able to more accurately determine whether or not a cellular cut-off has occurred. It also permits the reconnect feature to be implemented even when the called party joins a conference call.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention automatically reconnects a phone call to a cellular subscriber by accurately determining when a cellular cut-off has occurred. One embodiment of the invention, for use in speech enabled systems, uses speech recognition algorithms to make this determination. Further embodiments of the invention permit taking the calling party&#39;s feedback before attempting to reconnect the call. Still further embodiments of the invention permit the reconnect feature to be enabled/disabled in real time. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     Various embodiments of the present invention will now be described in detail in conjunction with the annexed drawings, in which:  
         [0008]      FIG. 1  is a schematic representation of a call being transferred to a called party&#39;s cell phone; and,  
         [0009]      FIG. 2  is functional diagram describing the process by which one embodiment of the invention recognizes a reconnect is appropriate and reconnects the dropped phone call. 
     
    
     DETAILED DESCRIPTION  
       [0010]     The present invention is applicable to telephone systems which have call rerouting algorithms for contacting the called party at alternative phone numbers stored in the system. These algorithms utilize separate telephony channels for the inbound and outbound legs of the call. An example of such a system is a system marketed by Avaya as the “Unified Communications Center R1.1.” and which is described at Avaya&#39;s product information web site, 
        http://www.avaya.com/ac/common/index.jhtml?location=M1H1005G1012F2055P3131N4905.        
 
         [0012]      FIG. 1  illustrates such a system in which a calling party places a call on his phone  102  to a called party&#39;s cell phone  104  through the called party&#39;s enterprise network  106  comprising a PBX  108  and a telephony server  110 . While being depicted as separate entities, it is contemplated by the invention that the functions of the PBX  108  and the telephony server  110  can be combined in one physical unit. Although not shown in  FIG. 1 , the calling party may have originated the phone call using a land-line phone. Consequently, it is contemplated by the invention that the telephony network  112  over which the call is completed comprises both PSTN (public switched telephone network) and cellular communications.  
         [0013]     Of significance to the invention is that the telephony server  110  is equipped with the feature whereby a call original directed to a subscriber&#39;s number is rerouted to an alternative location number. These systems are well known in the art and permit the user to store alternative numbers where he is most often contacted (i.e., their desk, home, mobile phone, etc.). These numbers can be readily changed and/or prioritized by various interfaces with the user. Once a call is rerouted to the called party cell phone  104 , the server  110  has access to both inbound  114  and outbound  116  legs of the call.  
         [0014]     In the prior art call reconnect systems, an attempt is made to identify the occurrence of a cellular cutoff. This identification occurs by simply measuring the time duration from when the called party has cleared down while the caller is still holding on. If the time period is exceeded, the system will automatically place a call back to the called party while a voice message is communicated to the calling party advising him that a reconnect is being attempted.  
         [0015]     The present invention improves upon the prior art systems in which the server  110 , attempts to identify when a call cellular cut-off has occurred. The present invention can be readily implemented using the hardware of a conventional prior art server which implements the find me/follow me feature discussed above. The novel features of the invention are realized by application of additional algorithms which are incorporated into the server&#39;s functions.  
         [0016]      FIG. 2  functionally illustrates an exemplary call that is reconnected by the present invention. First, the calling party calls the subscriber (a), perhaps at his desk phone number. The telephone server reroutes that call (b) in accordance with alternative numbers stored in the subscriber&#39;s profile and a connection with the subscriber&#39;s cell phone occurs (c). At some time thereafter, communication with the called party is lost (d). In the embodiment of the invention depicted in step (e), an attempt is made to identify the dropped connection as a network problem. In additional embodiments of the invention depicted as step (f), a message is then communicated to the calling party asking if he wants to reconnect the call. If he responds in the affirmative (g), the call is re-established (h).  
         [0017]     The present invention permits the called subscriber to enable and disable the dropped call reconnect feature (e.g., via DTMF key pad or speech commands). This feature is particularly useful should the called party wish to drop from a conference call.  
         [0018]     As noted in step (f) of  FIG. 2 , one embodiment of the present invention requests input from the calling party, rather than merely sending a message that the call attempted to be reconnected. By way of example, this message may say “Your phone connection appears to have been unintentionally dropped. Please press or say ‘1’ if you wish to have this connection automatically reestablished”. The invention then waits a fixed period of time to receive this authorization to reconnect the call. This waiting period would be a system parameter that is assigned a default value but which is readily changeable. Only if the authorization is received would a reconnecting be attempted.  
         [0019]     An alternative embodiment of the invention is applicable to speech enabled systems. An example of such a system is marketed by Avaya and is described in their product information web site, 
        http://support.avaya.com/japple/css/japple?PAGE=avaya.css.CSSLvl1&amp;temp.groupID=139233. 
 
 These systems would detect specific words like “bye” or “good-bye” which precede the called party connection being dropped. As the invention is a service provided to a subscriber, additional embodiments of the invention contemplate that his typical personal phone conversation closing remarks be entered as models into his data base profile. The user&#39;s voice could be used to create these model entries thereby improving the speech recognition accuracy of the system. In one embodiment of the invention, the detection of these closing words would be deemed by the system as confirmation of the call being completed (and intentionally terminated) and accordingly, the system would not attempt a reconnect. Thus, returning to  FIG. 2 , this embodiment of the invention would terminate the process at step (e) and not request input from the calling party 
       
 
         [0022]     As noted above, under the proper conditions the invention will attempt a reconnect of the phone call with the calling party. Of course, the network problem which caused the dropped connection, may not have been remedied (e.g., the called party is stuck in traffic in a tunnel). In additional embodiments of the invention, the system has settable parameters as to the number of times it attempts to reconnect and a time interval between such attempts. Should all these attempts prove unsuccessful, the calling party is given the option of leaving a message in the called party&#39;s voice mail by various means that are well known in the prior art.  
         [0023]     It should be noted that most of the options discussed above (e.g., settable parameters, disabling of reconnect feature) are available to the called subscriber. Additional embodiments of the invention give the calling party an option as well. In the situation where one or more reconnect attempts are made, the calling party can terminate the attempt at reconnecting. Thus for example, he need not wait for 10 reconnect attempts to occur which are spaced 30 seconds apart. Absent any special system feature, he could of course, simply hang up to avoid this wait. However, doing so will not permit him to leave a voice mail message. These additional embodiments of the invention permit the calling party to enter or say a code that would be recognized by the system, immediately terminate the reconnect attempt(s) and give him access to the called party&#39;s voice mail.  
         [0024]     It will be understood that the forgoing description of the invention is by way of example only, and variations will be evident to those skilled in the art without departing from the scope of the invention, which is as set out in the appended claims.