in one embodiment , the present invention includes or interfaces with location tracking functionality as described in related to u . s . patent application ser . no . 11 / 539 , 292 for “ starter - interrupt device incorporating global positioning system functionality ”, filed oct . 6 , 2006 , the disclosure of which is incorporated herein by reference . one skilled in the art will recognize that the present invention can be implemented with or without such location tracking functionality . for illustrative purposes , the description provided herein sets forth the invention in the context of vehicles . however , one skilled in the art will recognize that the invention can be used in connection with any product . for purposes of the following description , “ vehicle owner ”, “ owner ”, and “ user ” are synonymous and can refer to any individual who is interacting with the components of the present invention . referring now to fig1 , there is shown a block diagram depicting an overall architecture for an embodiment of the invention . according to one embodiment onboard device 111 is installed in vehicle 109 . onboard device 111 can be pre - installed or can be an add - on component . in one embodiment , onboard device 111 is connected to vehicle starter circuitry 112 so as to provide the ability to selectively disable vehicle 109 in the event of a geo - fence violation . this connection is optional , and is not an essential characteristic of the invention . onboard device 111 includes processor 115 which performs various functions in connection with the operation of the invention . bluetooth , rfid or rf interface 113 detects signals from portable device 116 ( such as a key fob , cellular telephone , or some other device ) held by vehicle owner 110 . interface 113 can take any known form for detecting the presence or absence of portable device 116 . in one embodiment , as described in more detail below , a geo - fence can be activated in response to the absence of portable device 116 , so that the invention activates the geo - fence when owner 110 parks vehicle 109 and walks away . onboard device 111 also includes global positioning system ( gps ) module 114 , which uses well - known techniques for determining the position of vehicle 109 by communication with satellites . in one embodiment , gps module 114 is external to onboard device 111 , so that onboard device 111 operates in connection with separate gps hardware that may be installed in vehicle 109 . wireless network interface 120 communicates via wireless network 105 or by some other means with operations center 101 . wireless network 105 may be any conventional cellular network , pager network , or other mechanism for transmitting information between vehicle 109 and operations center 101 . in one embodiment , operations center 101 includes wireless network interface 106 facilitating communication via network 105 . operations center 101 contains various components for implementing the present invention . in one embodiment , operations center 101 is situated at some central location . appropriate communications infrastructure , such as internet , wireless , and / or telecommunications connectivity is provided , so as to allow operations center 101 to communicate with other elements of the overall system . processor 102 at operations center 101 performs many of the functions of the present invention , including controlling the operation of various components of operations center 101 . mapping module 116 performs mapping functions associated with the present invention , including for example determining vehicle 109 movement outside an activated geo - fence , as described in more detail below . processor 102 also includes administrator user interface 103 allowing system administrator 104 to control and configure the operation of the system . processor 102 also includes owner user interface 104 allowing owner 110 to interact with the system , for example to specify conditions in which a geo - fence should be activated , and to specify the type of alerts to be issued in the event of geo - fence boundary violations . as described in more detail below , vehicle owner 110 can also directly activate and / or con figure 117 the system via user interface 104 . operations center 101 issues geo - fence violation alerts 107 under certain conditions , such as when a geo - fence is active and vehicle 109 position is outside the geo - fence . geo - fence violation alerts 107 can be transmitted using any known communications medium , including email , sms , instant message , automated telephone call , or the like . referring also to fig2 , there is shown a flow diagram depicting an overall method of activating a geo - fence according to an embodiment of the present invention . referring also to fig5 a through 5e , there is shown an example of a sequence of activating a geo - fence and responding to a geo - fence violation , according to an embodiment of the present invention . as mentioned above , the invention is described in connection with a technique for activating a geo - fence for a vehicle ; however , one skilled in the art will recognize that the invention can be used in connection with any asset , and is not limited to operation with a vehicle . as shown in fig5 a and 5b , owner 110 parks 201 vehicle 109 . owner 110 locks 202 vehicle 109 . the locking step 202 is optional , and can be omitted . geo - fence 501 is activated 203 . in one embodiment , activation 203 of geo - fence 501 takes place automatically in response to vehicle 109 being locked 202 . in another embodiment , activation 203 takes place automatically in response to some other trigger event , such as detection that a portable device 116 carried by owner 110 has been moved away from vehicle 109 . proximity of portable device 116 to vehicle 109 can be detected by known techniques that are used for remote keyless entry systems , such as by detecting the presence or absence of a radio frequency signal with a designated , distinct digital identity code associated with a particular portable device 116 . in one embodiment , interface 113 located in vehicle 109 ( either as part of onboard device 111 or as a separate component ) detects the presence or absence of portable device 116 . in another embodiment , activation 203 takes place automatically in response to any other trigger event , including but not limited to : the engine being turned off ; the key being removed from the ignition ; detection that the vehicle has not moved in some period of time ; detection that the vehicle is in a particular location ; or the like . in another embodiment , activation 203 takes place in response to an explicit activation command or operation . for example , owner 110 can press a button on portable device 116 initiating activation 203 of geo - fence 501 . alternatively , owner 110 can press a button on onboard device 111 , enter a code on a keypad in vehicle 109 , or send a text message , email message , instant message , or other communication directly to operations center 101 . alternatively , owner 110 can visit a website , log in using an authentication mechanism , and indicate that geo - fence 501 should be activated ; the website can communicate this command to operations center 101 . in another embodiment , activation 203 takes place at some preset time of day , such as for example between 11 pm and 6 am , unless countermanded by owner 110 . one skilled in the art will recognize that many other trigger events , operations , and mechanisms for initiating activation 203 of geo - fence 501 can be used . referring also to fig3 , there is shown a flow diagram depicting a method of establishing a geo - fence 501 based on a current vehicle 109 position , according to an embodiment of the present invention . trigger event occurs 301 , whether automatic or manual . the system determines 302 the current position of vehicle 109 , for example by well - known gps techniques using gps module 114 . then , based on the current position and other settings and parameters , the system establishes 303 geo - fence 501 . in one embodiment , the present invention avoids the need for owner 110 or any other individual to manually specify the parameters , bounds , size , or shape of geo - fence 501 or the region defined by geo - fence 501 . rather , geo - fence 501 is established 303 based on the current position of vehicle 109 and , optionally , other factors . for example , in one embodiment , geo - fence 501 is established as a region centered around the current position of vehicle 109 and having a radius according to some predetermined configuration parameter . in one embodiment , geo - fence 501 can have different shape , size , or characteristics depending on various factors , such as but not limited to : owner - defined preferences ; system - wide settings ; administrator - defined preferences ; current location of vehicle 109 ; geographic considerations ; and the like . fig5 d depicts vehicle 109 with geo - fence 501 established and active . in one embodiment , geo - fence 501 is established by processor 115 ; specifically , vehicle 109 position is determined by signals from gps module 114 , and processor 115 establishes a radius according to some predetermined configuration parameter . in another embodiment , geo - fence 501 is established by operations center 101 ; specifically , vehicle 109 position is determined by signals from gps module 114 sent to the operations center 101 via wireless network 105 , and processor 102 establishes a radius according to some predetermined configuration parameter . in one embodiment , once geo - fence 501 has been established , the system of the present invention periodically or continuously monitors 304 vehicle 109 position with respect to geo - fence 501 . in one embodiment , position monitoring is performed by periodic signals from gps module 114 to operations center 101 via wireless network 105 , so that processor 102 can compare current vehicle 109 position with geo - fence 501 to detect geo - fence violations . in another embodiment , the system of the present invention transmits geo - fence 501 information to vehicle 109 so that a geo - fence violation can be detected locally by onboard device 111 at vehicle 109 . thus , the specific parameters of geo - fence 501 can be stored at operations center 101 , or at vehicle 109 , or at both locations . in some embodiments , the system can be configured to receive periodic transmissions from onboard device 111 even when no geo - fence violation has taken place , so that if onboard device 111 is disabled or inoperative , the lack of transmissions can cause an alert to be issued to indicate a possible geo - fence violation . thus , a thief cannot disable the system by tampering with or destroying onboard device 111 . referring now to fig4 , there is shown a flow diagram depicting a method of responding to a geo - fence violation , according to an embodiment of the present invention . fig5 e depicts a geo - fence violation , where vehicle 109 is leaving the area defined by geo - fence 501 , for example if it is being stolen . the geo - fence violation is detected 401 in one of several ways . in one embodiment , onboard device 111 has access to the parameters of geo - fence 501 and detects the current position of vehicle 109 via gps module 114 ; if the current position is outside geo - fence 501 , onboard device 111 sends a signal to operations center 101 via wireless network 105 or by some other means . in another embodiment , the parameters of geo - fence 501 are stored at operations center 101 , and onboard device 111 periodically sends a signal with vehicle 109 position to operations center 101 ( or sends a signal when its current location has changed by more than some predetermined amount ); the comparison between vehicle 109 position and geo - fence 501 takes place at operations center 101 rather than at vehicle 109 . when a geo - fence violation is detected 401 , operations center 101 issues one or more alerts according to predefined settings and preferences . for example , operations center 101 can transmit a geo - fence violation alert 107 to owner 110 and / or to an external agent 108 such as a local police department . transmission of alert 107 can take place across any known communication channel or channels , including for example : a telephone call , an email message , an sms message , an instant message , or the like . alert 107 to external agent 108 can be sent over police radio or other mechanisms , if desired . additional information , such as current vehicle location , speed , description , or the like , can also be transmitted as part of alert 107 so as to assist in recovery of vehicle 109 . in this manner , the system of the present invention provides a mechanism by which vehicle theft can be quickly detected , and appropriate action can be taken promptly . in one embodiment , onboard device 111 is optionally connected to vehicle starter circuitry 112 so that vehicle 109 can be disabled when a geo - fence violation is detected . accordingly , based on predefined parameters and / or in response to a command from administrator 104 or owner 110 , onboard device 111 can disable vehicle 109 . a signal to disable vehicle 109 can be sent from operations center 101 to vehicle , for example via wireless network 105 . alternatively , onboard device 111 can disable vehicle 109 based on local determination of a geo - fence violation , such as in a configuration where geo - fence parameters are stored locally at onboard device 111 in vehicle 109 . the particular conditions in which the vehicle is disabled can be configured in advance by owner 110 , or by administrator 104 , or by some other party . alternatively , in one embodiment , when a geo - fence violation alert 107 is received by owner 110 or by external agent 108 , the owner 110 or external agent 108 can be given an opportunity to indicate whether vehicle 109 should be immediately disabled . if feasible and if owner 110 or external agent 108 requests disablement , a signal can be sent to onboard device 111 to disable vehicle 109 . several embodiments can be implemented using the above - described architecture and methods , and variations thereof . the following are three examples of specific use cases including descriptions of specific technologies , protocols and methodologies . a communication link such as bluetooth or rfid is established between a portable device 116 ( such as a key fob , cellular telephone , or other device ) carried by owner 110 and onboard device 111 . when onboard device 111 no longer detects the presence of portable device 116 , onboard device 111 establishes a geo - fence . for example , processor 115 can calculate geo - fence coordinates based on a predefined boundary rule stored in processor 115 . alternatively , onboard device 111 can send a message via wireless network 105 to operations center 101 to initiate activation of a geo - fence to lock down vehicle 109 movement . upon receiving the message , operations center 101 performs a gps locate for vehicle 109 and calculates geo - fence coordinates based on a predefined boundary rule . operations center 101 sends a message over wireless network 105 to onboard device 111 including the established geo - fence coordinates . onboard device 111 is then able to detect geo - fence violations . if vehicle 109 violates an active geo - fence by leaving the defined region , a boundary violation message is sent over wireless network 105 to operations center 101 . upon receiving the boundary violation message , operations center 101 executes a “ boundary violation routine ” which sends out boundary violation messages based on a notification rule set for the particular vehicle 109 . this may result in notifications to owner 110 and / or external agent 108 , as well as possibly sounding a local alarm , and / or disabling vehicle 109 . when onboard device 111 re - establishes connection with portable device 116 , onboard device 111 deactivates the programmed geo - fence , allowing vehicle 109 to be moved without triggering a boundary violation . owner 110 presses an “ activate ” button or enters a code on a portable device 116 ( such as a key fob or other device such as a cellular telephone ). this causes a signal to be sent , for example via bluetooth or rfid , to onboard device 111 , indicating that a geo - fence should be established . for example , processor 115 can calculate geo - fence coordinates based on a predefined boundary rule stored in processor 115 . alternatively , onboard device 111 can send a message via wireless network 105 to operations center 101 to initiate activation of a geo - fence to lock down vehicle 109 movement . upon receiving the message , operations center 101 performs a gps locate for vehicle 109 and calculates geo - fence coordinates based on a predefined boundary rule . operations center 101 sends a message over wireless network 105 to onboard device 111 including the established geo - fence coordinates . onboard device 111 is then able to detect geo - fence violations . if vehicle 109 violates an active geo - fence by leaving the defined region , a boundary violation message is sent over wireless network 105 to operations center 101 . upon receiving the boundary violation message , operations center 101 executes a “ boundary violation routine ” which sends out boundary violation messages based on a notification rule set for the particular vehicle 109 . this may result in notifications to owner 110 and / or external agent 108 , as well as possibly sounding a local alarm , and / or disabling vehicle 109 . owner 110 presses a “ deactivate ” button or enters a code on a portable device 116 . onboard device 111 deactivates the programmed geo - fence , allowing vehicle 109 to be moved without triggering a boundary violation in one embodiment , the activate signal may be sent automatically when owner 110 locks vehicle 109 via portable device 116 ( such as a key fob ), and the deactivate signal may be sent automatically when owner 110 unlocks vehicle 109 via portable device 116 . owner 110 sends an sms , text , instant message , or email message from an appropriately enabled device ( such as a cellular telephone or pda ) directly to operations center 101 indicating that a geo - fence should be established . this message can be sent when owner 110 is at the vehicle or from any other location . upon receiving the message , operations center 101 performs a gps locate for vehicle 109 and calculates geo - fence coordinates based on a predefined boundary rule . operations center 101 sends a message over wireless network 105 to onboard device 111 including the established geo - fence coordinates . onboard device 111 is then able to detect geo - fence violations . if vehicle 109 violates an active geo - fence by leaving the defined region , a boundary violation message is sent over wireless network 105 to operations center 101 . upon receiving the boundary violation message , operations center 101 executes a “ boundary violation routine ” which sends out boundary violation messages based on a notification rule set for the particular vehicle 109 . this may result in notifications to owner 110 and / or external agent 108 , as well as possibly sounding a local alarm , and / or disabling vehicle 109 . owner 110 sends an sms , text , instant message , or email message from an appropriately enabled device ( such as a cellular telephone or pda ) directly to operations center 101 to deactivate the geo - fence . again , this message can be sent when owner 110 is at the vehicle or from any other location . operations center 101 sends a message over wireless network 105 to onboard device 111 to deactivate the geo - fence . onboard device 111 deactivates the programmed geo - fence , allowing vehicle 109 to be moved without triggering a boundary violation . one skilled in the art will recognize that the above - described examples of use cases are intended to be illustrative , rather than limiting , of the scope of the claimed invention . in addition , the use cases can be combined , so that activation by one mechanism can be followed by deactivation by another mechanism . for example , the geo - fence can be established via the active cellular - based method , and subsequently deactivated by the passive device - based method . the above description includes various specific details that are included for illustrative purposes only . one skilled in the art will recognize the invention can be practiced according to many embodiments , including embodiments that lack some or all of these specific details . accordingly , the presence of these specific details is in no way intended to limit the scope of the claimed invention . in the specification , certain components of the invention may be described in terms of algorithms and / or steps performed by a software application . in many cases , such descriptions are intended to set forth the invention using representations that are commonly used among those of skill in the arts . accordingly , any descriptions that refer to algorithms , method steps , functional components , and the like , shall be considered to encompass electrical , magnetic , optical , and / or mechanical signals representing such algorithms , method steps , functional components , such signals being capable of being stored , transmitted , input , output , and / or otherwise manipulated . reference to these signals as variables , bits , symbols , values , and the like may appear herein and is not intended to limit the scope of the claimed invention in any way . all such terms , and any similar terms , are to be considered labels only , and are intended to encompass any appropriate physical quantities or other physical manifestations . any particular naming or labeling of the various modules , protocols , features , and the like is intended to be illustrative ; other names and labels can be used . in addition , various terms such as “ processing ”, “ calculating ”, “ determining ”, “ transmitting ”, or the like , may be used herein . such terms are intended to refer to processes performed by a software and / or hardware device such as a computer system . such terms refer to various types of manipulation and / or transformation of physical and / or electronic components such as registers and memories within the device . these physical and / or electronic components typically represent data elements to be transformed , transmitted , and / or output . furthermore , the invention can be implemented as a method , system , computer program product , user interface , or any combination thereof . the present invention also relates to a system for performing various steps and operations as described herein . this system may be a specially - constructed device such as an electronic device , or it may include one or more general - purpose computers that can follow software instructions to perform the steps described herein . multiple computers can be networked to perform such functions . software instructions may be stored in any computer readable storage medium , such as for example , magnetic or optical disks , cards , memory , and the like . the method steps , user interface layouts , displays , and other components described herein can be implemented on any computer , network , or other apparatus capable of performing the functions described . no limitation as to operation on a particular type of system or apparatus is implied . no particular programming language is required ; rather , any type of programming language can be used to implement the present invention . references to “ one embodiment ” or “ an embodiment ” indicate that a particular element or characteristic is included in at least one embodiment of the invention . although the phrase “ in one embodiment ” may appear in various places , these do not necessarily refer to the same embodiment . one skilled in the art will recognize that the invention can be practiced according to many embodiments other than those described herein , without departing from the essential characteristics of the present invention . the particular descriptions set forth above are intended to be illustrative examples only , and are not intended to limit the scope of the invention .