Patent Publication Number: US-2018034828-A1

Title: Positive disconnect unit

Description:
RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Application No. 62/368,412 entitled “Positive Disconnect Unit” filed Jul. 29, 2016, the entire contents of which is hereby incorporated by reference. 
    
    
     Communication security is a vital part of many aspects of government and business. While encryption and other means of signal obfuscation may provide a layer of security for communication devices in operation, proper communication security must also consider preventing or mitigating unintentional signal transmissions. For example, software controlling a communication session (e.g., a “soft phone”, an internet communication session such as Skype, etc.) may include a “mute” feature that purports to prevent transmission of sounds and/or images during a phone call or other communication session. However, even when such a mute feature is activated, an accessory (e.g., a microphone, a telephone handset, a camera, etc.) may still operate receive inputs, generate output signals based on the received inputs, and send the output signals to a communication device. This is because the mute feature typically only functions at a software level to block the output signals (received from an accessory) from being transmitted by the communication device. However, because the communication device still receives the output signals from the accessory, it is possible for the communication device to be compromised by an attacker (e.g., via a software and/or hardware exploit), who may then eavesdrop on the output generated from the accessory. 
     SUMMARY 
     Various embodiments include systems and methods of positively disconnecting electronic signal paths from an accessory device (e.g., an input device) to block transmission of a signal from the input device to a communication device. In some embodiments, a disconnect unit may electromechanically break an electronic signal path, such as an audio path or a USB path, between the accessory and the communication device. In some embodiments, the disconnect unit may maintain communication with the communication device on behalf of the accessory so that signal paths between the accessory and the communication device may be opened (to disconnect the signal paths between the accessory and the communication device) and closed (to reestablish the signal path), and input from the accessory may be provided to the communication device (e.g., to continue a communication session) without a delay that may be caused, for example, by reinitialization of a driver for the input device. In some embodiments, the disconnect unit may open and/or close the signal path while maintaining a communication session that uses input from the accessory. 
     Various embodiments may include a disconnect unit, including a first interface, configured to communicate with an accessory, a second interface, configured to communicate with a communication device, a relay, configured to physically connect a communication path between the first interface and the second interface, and a codec unit, configured to maintain a software-level connection with the communication device via the second interface on behalf of the accessory. In some embodiments, the relay may be configured to physically disconnect the communication path in a default operating state. In some embodiments, the relay may be configured to physically connect the communication path in a connected operating state. In some embodiments, the relay may include an electromechanical device configured to physically connect the communication path between the first interface and the second interface. 
     Some embodiments may further include a user interface, configured to receive an input, wherein the relay may be configured to physically connect the communication path in response to the input received at the user interface. In some embodiments, the codec unit may be configured to maintain the software-level connection with the communication device when the communication path is physically disconnected. 
     Some embodiments may further include a timer unit, configured to count a first time period during which the disconnect unit may operate with the communication path physically connected. In such embodiments, the timer unit may be configured to send a signal to the relay to physically disconnect the communication path in response to determining that the first time period has expired. In some embodiments, the timer unit may be configured to count a second time period after the first time period has expired, and may be configured to send a signal to the relay to physically disconnect the communication path in response to determining that the second time period has expired. 
     Various embodiments may include an electrical circuit, including a first interface, configured to communicate with an accessory, a second interface, configured to communicate with a communication device, a relay, configured to physically connect a communication path between the first interface and the second interface, and a codec unit, configured to maintain a software-level connection with the communication device via the second interface on behalf of the accessory. In some embodiments, the codec unit may be electrically coupled to the second interface. In some embodiments, the relay may be electrically coupled to the first interface. In some embodiments, when the communication path is physically connected by the relay, the relay may be electrically coupled to the codec unit. In some embodiments, the codec unit is may be configured to maintain the software-level connection with the communication device via the second interface on behalf of the accessory when the relay physically disconnects the communication path. 
     Various embodiments may include a method of performing operations of the embodiments summarized above. Various embodiments may include a non-transitory processor-readable storage medium having stored thereon processor-executable software instructions configured to cause a processor to perform operations of the embodiments summarized above. Various embodiments may include a disconnect unit and/or an electrical circuit that includes means for performing functions of the embodiments summarized above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments, and together with the general description given above and the detailed description given below, serve to explain the features of various embodiments. 
         FIG. 1  is a block diagram of a communication system including a disconnect unit according to various embodiments. 
         FIGS. 2-4  are component diagrams illustrating an embodiment disconnect unit according to various embodiments. 
         FIG. 5  is a block diagram illustrating a system including a disconnect unit according to various embodiments. 
         FIGS. 6, 7A, and 7B  are circuit diagrams illustrating components of an embodiment disconnect unit. 
         FIG. 8  is a process flow diagram illustrating a method for positively disconnected a signal path according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of various embodiments or the claims. 
     Conventional communication security solutions use encryption and signal obfuscation techniques to provide a layer of security for communication devices (e.g., laptop computing devices, smartphones, etc. etc.) and their accessories. However, conventional solutions do not adequately identify and prevent unintentional or surreptitious signal transmissions. 
     Software applications controlling a communication session (e.g., a “soft phone”, an internet communication session such as Skype, etc.) often include a “mute” feature. Activating the mute feature causes the software to electronically prevent transmission of sounds and/or images during communication session (e.g., phone call). Yet, the communication device&#39;s accessories (e.g., a microphone, camera, etc.) still capture inputs (e.g., sounds, etc.), generate electronic output signals based on the inputs, and send the output signals to the communication device. The communication device simply does not transmit these output signals (e.g., as part of the communication session, etc.) when the mute feature is activated. 
     Due to these characteristics, hackers and thieves may gain access to sounds and images captured by the communication device (or its accessories), even after the mute feature is activated. For example, a hacker may install malware on the communication device that modifies or otherwise compromises the device&#39;s hardware and/or software components. Such modifications may cause the device to surreptitiously record and/or transmit the output signals to a covert network server, regardless of whether the “mute” feature has been activated. The hackers or thieves may then access the covert server to eavesdrop on the users of the communication device, even when the “mute” feature is active. 
     To overcome the above-described limitations of existing solutions, the various embodiments include systems and methods of positively disconnecting signal paths between the communication device and its input or accessory devices. By positively disconnecting the signal paths, the various embodiments prevent inadvertent, unintentional, or surreptitious signal transmissions, and better protect the device from hackers, thieves, and cyberattacks. 
     In some embodiments, the communication device may be equipped with, or in communication with, a disconnect unit. The disconnect unit may be configured to electromechanically break a signal path, such as an audio path or a USB path, between an accessory device and the communication device. 
     In some embodiments, the disconnect unit may be configured to maintain communications with the communication device on behalf of the accessory so that signal paths between the accessory and the communication device may be opened (e.g., to disconnect the signal paths between the accessory and the communication device) and closed (e.g., to reestablish the signal path). Also, by maintaining communications, the disconnect unit may provide or relay input from the accessory to the communication device (e.g., to continue a communication session) without delay. For example, the disconnect unit may prevent or avoid delays often caused by, for example, the reinitialization of a driver for an input/accessory device. In some embodiments, the disconnect unit may open and/or close the signal path while maintaining a communication session that uses the signals received from the accessory. 
     In some embodiments, the disconnect unit may be configured to positively disconnect the signal paths in a default operating state. 
     In some embodiments, the disconnect unit may be configured to positively disconnect the signal paths when an accessory enters or is placed in an off-hook state, a non-operational state, or other similar state. 
     In some embodiments, the disconnect unit may be configured to positively disconnect the signal paths when a “mute” or “hold” function of the disconnect unit is activated. In some embodiments, the disconnect unit may be configured to activate its “mute” or “hold” function in response to determining that a “mute” feature of a software application controlling a communication session has been activated. 
     In some embodiments, the disconnect unit may include a user interface, such as switch, which may enable closing or restoring the electronic paths. The user interface element may allow the disconnect unit to enter and operate in a connected state and/or to enter a disconnected state. The disconnect unit may also include an indicator component, such as a visual indicator or another type of indicator, that identifies the operating state of the disconnect unit and/or of a state of the signal paths. For example, the disconnect unit (or its indicator component) may be configured to activate a red light to indicate that the signal paths are enabled, and activate a green light to indicate that the signal paths are disabled. 
     In some embodiments, the disconnect unit may include one or more metallic-contact disconnect switches or relays. The metallic-contact disconnect switches or relays may be configured to mechanically open (e.g., disconnect) a signal path. 
     In some embodiments, the disconnect unit may include controls for manual operation, such as to manually originate or answer a communication session, manually connect or disconnect the signal paths, etc. 
     In some embodiments, the disconnect unit may be configured to physically prevent signal transmissions from emanating or originating from the disconnect unit. For example, the disconnect unit may be configured to physically prevent audio signals from propagating of on any of the wires leaving the disconnect unit when the disconnect unit is active or in the default operating state. 
     In some embodiments, the disconnect unit may configured or arranged so that is unable to transmit a signal (such as an audio signal) when it is operating in the default operating state. In these embodiments, intrusive physical modifications within the disconnect unit would be required for signal transmission. 
       FIG. 1  illustrates a communication system  100  that includes a disconnect unit configured to connect and disconnect the signal paths in accordance with the various embodiments. In the example illustrated in  FIG. 1 , the system  100  includes a communication device  104  in the form of a personal computing device. The communication device  104  includes communication links to various accessories, such the illustrated headset  106 , camera  108 , and handset  110 . A disconnect unit  102  is interposed between the communication device  104  and the accessories  106 - 110 . The accessories  106 - 110  may communicate with the disconnect unit  102  via communication links  114 ,  116 , and  118 . The communication device  104  may communicate with the disconnect unit  102  over communication link  112 . 
     In the illustrated example, the communication device  104  includes a communication link  122  to a communication network  120 . The communication device  104  may also include a processor configured with processor-executable instructions to establish and use a communication session (e.g., a Skype videoconference, etc.) to other devices (not illustrated in  FIG. 1 ) via the communication network  120 . The communication session may include, for example, a Voice over Internet Protocol (VoIP) communication session or another similar communication session. 
     Each of the communication links  114 ,  116 , and  118  may conduct a signal from an accessory. For example, the headset  106  may include a microphone  106   a , which may generate a signal responsive to audio input that may be transmitted along the communication link  114 . As another example, the camera  108  may include a video input  108   a  and a microphone  108   b , each of which may generate a signal based on received input that may be transmitted along the communication link  116 . As another example, the handset  110  may include a microphone  110   a  and a speaker  110   b , both of which may generate a signal responsive to, for example, received audio input. Similarly, the handset  110  may include an optional cradle, which may include a microphone  110   c  (such as a “speakerphone” microphone) that may generate a signal responsive to received audio input. The signal generated by the handset  110  may be transmitted along the communication link  118 . 
     A signal transmitted along the communication links  114 ,  116 , and  118  may be received by the disconnect unit  102 . In some embodiments, the disconnect unit may block transmission of a signal that is received from the accessory  106 ,  108 ,  110  from the disconnect unit  102  to the communication device  104 . In some embodiments, the disconnect unit  102  may mechanically disconnect or break an electronic signal path between the accessory  106 ,  108 ,  110  and the communication device  104  to prevent the transmission of the signal that is generated by the accessory  106 ,  108 ,  110  to the communication device  104 . In some embodiments, the disconnect unit  102  may include circuitry and/or a processor that may maintain communication between the disconnect unit  102  and the communication device  104  in order to maintain a software-level connection between the disconnect unit  102  and the communication device  104  on behalf of the accessory  106 ,  108 ,  110 . In some embodiments, the circuitry and/or processor may include a CODEC (coder-decoder) unit that communicates with the communication device  104  in order to maintain the initialization of a device manager (such as, e.g., a device driver) for the accessory  106 ,  108 ,  110 . In such embodiments, the disconnect unit  102  may mechanically reconnect an electronic signal path between the accessory  106 ,  108 ,  110  and the communication device  104 , and the communication device  104  may receive input from the accessory  106 ,  108 ,  110  without a delay caused by re-initializing a device manager or device driver for the accessory  106 ,  108 ,  110 . In some embodiments, when the disconnect unit  102  is initially connected with the communication device  104 , the CODEC unit may initialize device drivers for one or more accessories. The CODEC unit may also load device drivers and/or CODEC software to the communication device  104 . The CODEC unit may maintain a software-level communication or connection with the communication device  104  regardless of whether the signal path(s) between the accessory  106 ,  108 ,  110  and the communication device  104  are open or closed. 
       FIGS. 2-4  illustrate a disconnect unit  200  that is suitable for preventing inadvertent, unintentional or surreptitious signal transmissions in accordance with the various embodiments. In some embodiments, the disconnect unit  200  may be the same as or similar to the disconnect unit  102  illustrated in  FIG. 1  and discussed above. 
     The disconnect unit  200  may include a body  202 , which may include a molded housing or another similar enclosure of various components of the disconnect unit  200 . The disconnect unit  200  may include a user interface  208 , such as one or more switches, sliders, buttons, touch panels, or another device to receive an input. In some embodiments, the user interface  208  may be disposed on or supported by the body  202 . In some embodiments, the user interface  208  may include an indicator  208   a  of an operating state of the disconnect unit  200 . For example, the indicator  208   a  may include a light, such as a light emitting diode (LED), configured to emit one or more colors indicative of the operating state of the disconnect unit  200 . 
     In various embodiments, the indicator  208   a  may include speaker to emit a sound, a haptic feedback device to vibrate, or another device to provide an indication of the operating state of the disconnect unit  200 . 
     In some embodiments, the user interface  208  may include a transparent or translucent cover within which the indicator  208   a  may be disposed. In some embodiments, a portion of the body  202  supporting the user interface  208  may be shaped such that the indicator  208   a  is visible from a substantially 360-degree angle around the disconnect unit  200 . For example, a top portion of the body  202  may be substantially curved such that the indicator  208   a  is visible from a substantially 360-degree angle around the disconnect unit  200 . 
     The body  202  may include a first panel  204  and a second panel  206 . Each of the first panel  204  and the second panel  206  may include one or more communication ports. 
     The first panel  204  may include a universal serial bus (USB) port  210 , an RJ-type port  212 , and one or more 3.5 mm ports  214 ,  216 ,  218 . The USB port  210  may enable the disconnect unit  200  to communicate with a USB device, such as a camera, headset, or handset. The RJ-type port  212  may enable the disconnect unit  200  to communicate with, for example, a telephone device or handset. In some embodiments, the one or more 3.5 mm ports  214 ,  216 ,  218  may include a microphone input port, a microphone/handset output port, and a telephone communication port. In some embodiments, the telephone communication port may be in communication with a telephone cradle or other device that may provide a signal indicating that an accessory (e.g., the telephone handset  110   a ) has been placed in an on-hook position, a non-use state, or into an idle state. For example, an accessory may provide a signal to the communication port  218  that a telephone handset has been placed in a handset cradle of the accessory. 
     The second panel  206  may include a power input port  220  and one or more communication ports  222 ,  224 . In some embodiments, the communication ports  222 ,  224  may enable communication with a communication device (e.g., the communication device  104 ) using an appropriate protocol, such as USB or another communication protocol. 
     The number, type, and disposition of various ports and connectors illustrated in  FIGS. 2-4  is merely exemplary, and in various embodiments the disconnect unit  200  may include any number and/or type of ports and connectors in a variety dispositions. 
       FIG. 5  illustrates a system including a disconnect unit  500  according to various embodiments. With reference to  FIGS. 1-5 , the disconnect unit  500  may include a user interface  502 , an indicator  504 , a timer unit  506 , one or more first interfaces  508 , one or more relays  510 , a CODEC unit  512 , one or more second interfaces  514 , and a power supply  524 . The various elements of the disconnect unit  500  may communicate over a communication link such as circuitry or a communication bus. 
     The disconnect unit  500  may communicate with an accessory  520  through the first interface  508  over a communication link  522 . In some embodiments, the accessory  520  may be similar to the headset  106 , the camera  108 , or the telephone  110 . The first interface  508  may include one or more communication ports, which may be similar to the communication ports  210 ,  212 ,  214 ,  216 ,  218 . The disconnect unit  500  may also communicate with the communication device  516  through the second interface  514  over a communication link  518 . The communication device  516  may be similar to the communication device  104 . The second interface  514  may include one or more communication ports, which may be similar to the communication ports  222 ,  224 . 
     The first interface  508 , the relay(s)  510 , the CODEC unit  512 , and the second interface  514  may form a signal path which may communicate signals between the accessory  520  and the communication device  516 . For example, the accessory  520  may generate a signal and transmit the signal over the communication link  522 . The first interface  508  may receive the signal and convey the signal to a relay  510 . The relay  510  may convey the signal to the CODEC unit  512 . The CODEC unit  512  may transmit the signal to the second interface  514 . The second interface  514  may send the signal to the communication device  516  via the communication link  518 . Similarly, the communication device  516  may generate a signal and transmit such signal to the accessory  520  in a reverse direction via the signal path. 
     In various embodiments, the disconnect unit  500  may include a default operating state in which signal path is open (i.e., disconnected) and a connected state in which the signal path is closed (i.e., connected). In some embodiments (which may be may be similar to the user interface  208 ) and may include one or more switches, sliders, buttons, touch panels, or another device to receive an input that may change the operating state of the disconnect unit  500 . For example, the user interface  502  may receive an input, and in response to the input the user interface  502  may send a signal to open (i.e., disconnect) or close (i.e., connect) the signal path. For example, the user interface  502  may send a signal responsive to an input to the one or more relays  510 . The relay(s)  510  may include one or more electromechanical devices that may physically open or close (i.e., physically disconnect or connect an electrical connection) in response to such signal. In some embodiments, the user interface  502  may be electrically and/or electronically isolated so that the user interface  502  may not be manipulated through any firmware or software. 
     In some embodiments, the relay(s)  510  may include one or more metallic-contact disconnect switches or relays that may mechanically open (e.g., disconnect) or close (e.g., connect) a signal path. In some embodiments, the relay(s)  510  may be physically isolated from any external wiring such that the relay(s)  510  cannot be controlled, overridden, or otherwise manipulated by software, firmware, telnet, or any other networked communication to the disconnect unit  500 . 
     When the relay(s)  510  are open, the disconnect unit  500  may physically prevent a signal that is received from the accessory  520  from being transmitted from the disconnect unit  500 , such as an audio signal, on any wires leaving the disconnect unit (e.g., from the interface(s)  514  to the communication link  518 ). In some embodiments, the relay(s)  510  may be open (e.g., the signal path may be disconnected) when the disconnect unit  500  is in the default operating state. In some embodiments, the disconnect unit  500  may be unable to transmit a signal to the communication device when operating in the default operating state except by intrusive physical modifications within the disconnect unit  500 . 
     The indicator  504  (which may be similar to the indicator  208   a ) may include one or more lights, speakers, haptic feedback devices, or another device that may provide an indication of an operating state of the disconnect unit  500 . The indicator  504  may provide a visual, audible, tactile, or other indication that the signal path is open or closed. For example, to indicate that the signal path is open (i.e., is disconnected), power may be supplied to a green LED, or an LED may be controlled to emit green light. As another example, to indicate that the signal path is closed (i.e., is connected), power may be supplied to a red LED, or an LED may be controlled to emit red light. In some embodiments, the indicator  504  may indicate all times when the physical isolation of signal path is not active (e.g., when the signal path is closed). In some embodiments, the indicator  504  may provide an indication in response to physical act (e.g., taking an instrument of accessory off-hook). 
     The CODEC unit  512  may include circuitry and/or processor that may communicate with the communication device  516  in order to maintain a software-level connection between disconnect unit  500  and the communication device  516  on behalf of the accessory  520 . In some embodiments, the software-level connection may include the initialization of a device manager (such as, e.g., a device driver) for the accessory  520 . In some embodiments, when the disconnect unit  500  and the communication device  516  are initially connected, the CODEC unit  512  and the communication device  516  may perform device driver negotiation for the accessory  520 . The disconnect unit  102  may mechanically disconnect and reconnect the signal path between the accessory  520  and the communication device  516 , and the communication device  104  may receive input from the accessory  520  without a delay caused by re-initializing a device driver for the accessory  520 . In some embodiments, when the disconnect unit is in the default operating state, the CODEC unit is prevented from passing audio signals electrically outside the disconnect unit. 
     The timer unit  506  may include a countdown timer  506   a  that may count a time period during which the disconnect unit  500  may operate in the connected state. In some embodiments, upon receiving an input to change the operating state of the disconnect unit  500  from the default operating state (i.e., signal paths disconnected) to the connected operating state (i.e., signal path connected), in addition to sending a signal to the relay(s)  510  to close the signal path, the user interface  502  may also send a signal to the timer unit  506 . In response to receiving the signal from the user interface  502 , for example, the timer unit  506  may initialize the countdown timer  506   a , which may count a duration of time (e.g., 15 minutes) during which the disconnect unit  500  may operate in the connected state. In some embodiments, in response to determining that the countdown timer  506   a  has expired, the timer unit  506  may send a signal to the relay(s)  510  to open the relay(s)  510 , disconnecting the signal path, and changing the operating state of the disconnect unit  500  to the default operating state. In some embodiments, in response to determining that the countdown timer  506   a  has expired, the timer unit  506  may also send the signal to the indicator  504 , which may provide an indication of the change in the operating state of the disconnect unit  500  (e.g., may provide an indication that the signal path is open). 
     Additionally or alternatively, in response to determining that the countdown timer  506   a  has expired, the timer unit  506  may initialize a warning timer  506   b . The warning timer may count a brief warning period (e.g., 10 seconds) at the end of which the timer unit  506  may send a signal to the relay(s)  510  to open the relays, disconnecting the signal path. The timer unit  506  may also send a signal to the indicator(s)  504  to provide an indication that the warning timer is counting down. In some embodiments, the indicator  504  may provide a flashing light, sound indication, haptic indication, or some other indication that the warning timer is counting down. In some embodiments, in response to determining that the warning timer  506   b  has expired, the timer unit  506  may send a signal to the relay(s)  510  to open the relay(s)  510  and disconnect the signal path, changing the operating state of the disconnect unit  500  to the default operating state. In some embodiments, during the warning period, if an input is received at the user interface  502 , the countdown timer and the warning timer may reset. In some embodiments, the countdown timer and the warning timer may reset without disconnecting an ongoing communication session (e.g., a call). 
     In some embodiments, disconnect unit  500  may receive a signal from an accessory via the interface  508  indicating that the accessory  520  has been placed in an on-hook position, a non-use state, or into an idle state. For example, an accessory may provide a signal that a telephone handset has been placed in a handset cradle of the accessory. In some embodiments, in response to receiving the signal that the accessory  520  has been placed in an on-hook position, the relay(s)  510  may open the signal path, and the disconnect unit  500  may operate in the default operating state. In some embodiments, the disconnect unit  500  may return to operating in the default operating state within one second of receiving the signal from the accessory  520 . 
     In some embodiments, the relay(s)  510  and the second interface  514  may communicate a signal directly, without the involvement of the CODEC unit  512 . For example, an accessory that employs a USB connection may not require, for example, the involvement of the CODEC unit  512  in order to maintain a software-level connection between disconnect unit  500  and the communication device  516  on behalf of the accessory  520 . 
     The power supply  524  may receive power, for example, from an electrical source such as alternating current (AC) or direct current (DC), or from the second interface  514  (e.g., power over USB). 
       FIGS. 6, 7A, and 7B  are circuit diagrams illustrating components of an embodiment disconnect unit  600 . With reference to  FIGS. 1-7B , the disconnect unit  600  may be similar to the disconnect unit  102 ,  200 , and  500 . 
     The disconnect unit  600  may include one or more accessory interfaces  606 ,  608 , and  610 . In some embodiments, the accessory interfaces  606 ,  608 ,  610  may be similar to the USB port  210 , the RJ-type port  212 , and/or the communication ports  212 ,  214 ,  216 , and/or to the first interface(s)  508 . The disconnect unit  600  may communicate with an accessory (not illustrated) via one or more of the accessory interfaces  606 ,  608 ,  610 . In some embodiments, the accessory may be similar to the headset  106 , the camera  108 , the telephone  110 , and/or the accessory  520 . The disconnect unit  600  may also include a communication device interface  616 . The disconnect unit  600  may communicate with a communication device (not illustrated) via the computing device interface  612 . In some embodiments, the second interface  616  may be similar to the communication ports  222 ,  224  and/or the second interface(s)  616 . 
     The disconnect unit  600  may also include a CODEC unit  604  and one or more relays  602 . The CODEC unit  604  may be similar to the CODEC unit  512 . The relays  602  (which may be similar to the relays  510 ) may include electromechanical elements to physically open or close electrical connections of the signal path. The accessory interfaces  606 ,  608 ,  610 , the relays  602 , the CODEC unit  604 , and the computing device interface  612  may form one or more signal paths that may communicate signals between the accessories and the communication device. 
     The disconnect unit  600  may include a USB port  616 , which may communicate with a USB port  618  via relays  620 . The USB port  616  may be similar to the communication ports  222 ,  224 , and may enable the disconnect unit  600  to communicate with the communication device. The USB port  618  may be similar to the communication port  210 , and may enable the disconnect unit  600  to communicate with a USB type accessory that may communicate with the communication device without passing a signal through the CODEC unit  604 . (An example of such a USB type accessory may include a USB camera.) The USB port  616 , the relays  620 , and the USB port  618  may form a signal path that may communicate signals between a USB type accessory and the communication device. In some embodiments, the signal path formed by the USB port  616 , the relays  620 , and the USB port  618  may enable the use of one or more USB accessories (e.g., a USB data drive, a USB hub to multiple accessories, etc.) as long as the signal path is closed. In some embodiments, the one or more USB accessories may be used during a time period during which the relays  620  are closed (e.g., a countdown period and/or a warning period), and at the expiration of the time period, the relays  620  may open, disconnected the signal path and rendering the one or more USB accessories in communication with the USB port  618  inaccessible. This feature may enable, for example, use of a USB accessory for the time period, after which the USB accessory is rendered inaccessible, and therefore secure, after the expiration of the time period. 
     The disconnect unit  600  may include a switch  614  (which may be similar to the user interface  208  and the user interface  502 ). Actuation of the switch  614  (e.g., through an input, such as a button press) may send a signal via a flip-flop switch  636  to relay drivers  630  and  640 . The relay driver  630  may send control signals via control signal outputs  638   b  to control signal inputs  638   a . The control signals received at the control signal inputs  638   a  may actuate the relays  602  to control the relays  602  to open or close their electrical connections. The relay driver  640  may send control signals via a control signal outputs  642   b  to control signal inputs  642   a . The control signals received at the control signal inputs  642   a  may actuate the relays  620  to control the relays  620  to open or close their electrical connections. In various embodiments, the disconnect unit  600  may include a default operating state in which the relays  602  and  620  are open (i.e., disconnected). In response to an input received at the switch  614 , the relay drivers  630 ,  640  may send signals instructing the relays  602 ,  620  to close, thereby connecting the respective electrical connections of the relays  602 ,  620 . 
     In some embodiments, the disconnect unit  600  may include a hook switch  622 , which may enable the disconnect unit  600  to receive an on-hook signal from an appropriate accessory, such as a handset or another similar accessory. The on-hook signal may indicate that the accessory has been placed in a non-use state or in an idle state. For example, the accessory may provide a signal to the hook switch  622  that a telephone handset has been placed in a handset cradle of the accessory. The hook switch  622  may send a signal via the flip-flop switch  636  to the relay drivers  630  and  640 . The relay drivers  630  and  640  may then send control signals via their respective control signal outputs  638   b  and  642   b  to control the relays  602  and  620  to open their respective electrical connections. 
     The disconnect unit  600  may include one or more indicators, such as LEDs  626  and LEDs  628 . The LEDs  626 ,  628  may be similar to the indicator  208   a  and the indicator  504 . In some embodiments, the LEDs  626  may be instructed via an LED driver  646  to provide an indication of an operating state of the disconnect unit  600 . For example, when a signal is sent to the relay drivers  630 ,  640  (for example, from the switch  614 ), a signal may also be sent to the LED driver  646 , which may control the LEDs  626  to provide an indication corresponding to the operating state of the disconnect unit  600 . For example, to indicate that the signal paths are open (i.e., are disconnected), power may be supplied to a green LED, or an LED may be controlled to emit green light. As another example, to indicate that the signal paths are closed (i.e., are connected), power may be supplied to a red LED, or an LED may be controlled to emit red light. 
     The disconnect unit  600  may include timers  632  and  634 . The timers  632 ,  634  may be similar to the timers  506   a  and  506   b  in the timer unit  506 . In some embodiments, when a signal is sent to the relay drivers  630 ,  640  (for example, from the switch  614 ), a signal may also be sent to the timer  632  (such as an initialization signal), and the timer  632  may count a time period during which the disconnect unit  600  may operate in the connected state. For example, the timer  632  may count a duration of time (e.g., 15 minutes) during which the disconnect unit  600  may operate in the connected state. In some embodiments, in response to determining that the timer  632  has expired, the timer  632  may send a signal to relay drivers  630  and  640  to open the relays  602  and  620 , respectively, disconnecting the signal paths, and changing the operating state of the disconnect unit  600  to the default operating state. In some embodiments, in response to determining that the timer  632  has expired, the timer  632  may also send the signal to the LED driver  646 , which may control the LEDs  626  to provide an indication of the change in the operating state of the disconnect unit  600 . 
     Additionally or alternatively, in response to determining that the timer  632  has expired, the timer  632  may send a signal (such as an initialization signal) to the timer  634 . The timer  634  may count a brief warning period (e.g., 10 seconds) at the end of which the timer  634  may send a signal to relay drivers  630 ,  640  to open the relays  602 ,  620 , disconnecting the signal paths, and changing the operating state of the disconnect unit  600  to the default operating state. In some embodiments, the timer  634  may also send a signal to the LEDs  628  to provide an indication that the warning timer is counting down. In some embodiments, the LEDs  628  may provide a flashing light to indicate that the timer  634  is counting down. In some embodiments, in response to determining that the timer  634  has expired, the timer  634  may send a signal to relay drivers  630 ,  640  to open the relays  602 ,  620 , disconnecting the signal paths. In some embodiments, the disconnect unit  600  may include a counter  624  may function with the timer  634  to determine whether the timer  634  has expired. In some embodiments, the counter  624  may count a number of flashes produced by the LEDs  628 . 
     The disconnect unit  600  may include a timer  646 , that may enable the timers  632  and  634  to be reset without changing a state of the relays  602 ,  620 . In some embodiments, the timer  646  may be set to a relatively short time period, such as ½ second or ¼ second. The timer  646  may permit or induce a delay for the duration of its time period to enable the timers  632  and  634  to be reset without changing the state of the relays  602 ,  620 . 
     In some embodiments, the disconnect unit  600  may include a power-on reset chip  644 . The power on-reset chip  644  may enable the disconnect unit  600  to begin operation after powering up in the default operating state (i.e., with the signal paths disconnected). In some embodiments, upon powering up the disconnect unit  600 , the power-on reset chip may send a signal via the flip-flop switch  636  to open the relays  602 ,  620 . 
       FIG. 8  is a process flow diagram illustrating a method  800  for mitigating an induced electrical signal from an appliance in a powered-off state. With reference to  FIGS. 1-8 , the method  800  may be implemented by a disconnect unit (e.g., the disconnect unit  102 ,  200 ,  500 ,  600 ). 
     In block  802 , the disconnect unit may operate in a default operating state. In the default operating state, one or more signal paths between an accessory and a communication device may be opened by the disconnect unit to prevent a signal received from the accessory from being sent by the disconnect unit to the communication device. 
     In optional determination block  804 , the disconnect unit may determine whether an on-hook signal has been received. For example, the disconnect unit may receive an on-hook signal from a hook switch (e.g., the hook switch  622 ). The on-hook signal may indicate that an accessory is in a non-use state or in an idle state. 
     In response to determining that the on-hook signal has been received (i.e., optional determination block  804 =“Yes”), the disconnect unit may continue to operate in the default operating state in block  802 . 
     In response to determining that the on-hook signal has not been received (i.e., optional determination block  804 =“No”), in determination block  806 , the disconnect unit may determine whether a user interface receives an input. In response to determining that the user interface does not receive input (i.e., determination block  806 =“No”), the disconnect unit may continue to operate in the default operating state in block  802 . 
     In response to determining that the user interface receives an input (i.e., determination block  806 =“Yes”), the disconnect unit may connect the one or more signal paths in block  808 . For example, the disconnect unit may operate in a connected state such that the accessory may communicate signals to the communication device. 
     In block  810 , the disconnect unit may provide an indication that the disconnect unit is operating in the connected state. For example, the disconnect unit may include one or more indicators that may indicate that the disconnect unit is operating in the connected state. 
     In block  812 , the disconnect unit may initialize a countdown timer. The countdown timer may count a time period during which the disconnect unit may operate in the connected state. 
     In determination block  814 , the disconnect unit may determine whether an on-hook signal is received. For example, the disconnect unit may receive an on-hook signal from an appropriate accessory, such as a handset or another similar accessory, which may provide a signal indicating that the accessory has been placed in a non-use state or in an idle state. 
     In response to determining that the disconnect unit has received an on-hook signal (i.e., determination block  814 =“Yes”), the disconnect unit may disconnect the one or more signal paths in block  826 . For example, the disconnect unit may operate in the default state such that the disconnect unit may block or prevent signals received from the accessory from being transmitted from the disconnect unit to the communication device. 
     The disconnect unit may then continue to operate in the default operating state in block  802 . 
     In response to determining that the disconnect unit has not received an on-hook signal (i.e., determination block  814 =“No”), the disconnect unit may determine whether the disconnect unit has received an input at the user interface in determination block  816 . 
     In response to determining that the disconnect unit has received an input at the user interface (i.e., determination block  816 =“Yes”), the disconnect unit may disconnect the one or more signal paths in block  826 . For example, the disconnect unit may operate in the default state such that the disconnect unit may block or prevent signals received from the accessory from being transmitted from the disconnect unit to the communication device. 
     In response to determining that the disconnect unit has not received an input at the user interface (i.e., determination block  816 =“No”), the disconnect unit may determine whether the countdown timer has expired in determination block  818 . 
     In response to determining that the countdown timer has not expired (i.e., determination block  818 =“No”), the disconnect unit may again determine whether the disconnect unit has received an on-hook signal in determination block  814 . 
     In some embodiments, in response to determining that the countdown timer has expired (i.e., determination block  818 =“Yes”), the disconnect unit may disconnect the one or more signal paths in block  826 . For example, the disconnect unit may operate in the default state such that the disconnect unit may block or prevent signals received from the accessory from being transmitted from the disconnect unit to the communication device. The disconnect unit may then continue to operate in the default operating state in block  802 . 
     In some embodiments, in response to determining that the countdown timer has expired (i.e., determination block  818 =“Yes”), in optional block  820  the disconnect unit may initialize a warning timer. The warning timer may count a brief warning period (e.g., 10 seconds) at the end of which the disconnect unit may disconnect the one or more signal paths. 
     In optional determination block  822 , the disconnect unit may determine whether the disconnect unit has received an input at the user interface. In response to determining that the disconnect unit has received an input at the user interface (i.e., optional determination block  822 =“Yes”), the disconnect unit may reinitialize the countdown timer in block  812 . In addition, the disconnect unit may stop the warning timer. 
     In response to determining that the disconnect unit has not received an input at the user interface (i.e., optional determination block  822 =“No”), the disconnect unit may determine whether an on-hook signal has been received in optional determination block  823 . For example, the disconnect unit may determine whether it has received an on-hook signal from a hook switch (e.g., the hook switch  622 ). 
     In response to determining that the on-hook signal has been received (i.e., optional determination block  823 =“Yes”), the disconnect unit may disconnect the one or more signal paths in block  826 . 
     In response to determining that the on-hook signal has not been received (i.e., optional determination block  823 =“No”), the disconnect unit may determine whether the warning timer has expired in optional determination block  824 . In response to determining that the warning timer has not expired (i.e., optional determination block  824 =“No”), the disconnect unit may again determine whether the disconnect unit has received an input at the user interface in optional determination block  822 . 
     In response to determining that the warning timer has expired (i.e., optional determination block  824 =“Yes”), the disconnect unit may disconnect the one or more signal paths in block  826 . For example, the disconnect unit may operate in the default state such that the disconnect unit may block or prevent signals received from the accessory from being transmitted from the disconnect unit to the communication device. 
     The disconnect unit may then continue to operate in the default operating state in block  802 . 
     Various embodiments illustrated and described are provided merely as examples to illustrate various features of the claims. However, features shown and described with respect to any given embodiment are not necessarily limited to the associated embodiment and may be used or combined with other embodiments that are shown and described. Further, the claims are not intended to be limited by any one example embodiment. For example, one or more of the operations of the disconnect unit  102 ,  200 ,  500 ,  600 , and of the method  800  may be substituted for or combined with one or more operations of the disconnect unit  102 ,  200 ,  500 ,  600 , and of the method  800  and vice versa. 
     The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the blocks of various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of blocks in the foregoing embodiments may be performed in any order. Words such as “thereafter,” “then,” “next,” etc. are not intended to limit the order of the blocks; these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular. 
     The various illustrative logical blocks, modules, circuits, and algorithm blocks described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and blocks have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the claims. 
     The hardware used to implement the various illustrative logics, logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of communication devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Alternatively, some blocks or methods may be performed by circuitry that is specific to a given function. 
     In various embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable medium or non-transitory processor-readable medium. The operations of a method or algorithm disclosed herein may be embodied in a processor-executable software module, which may reside on a non-transitory computer-readable or processor-readable storage medium. Non-transitory computer-readable or processor-readable storage media may be any storage media that may be accessed by a computer or a processor. By way of example but not limitation, such non-transitory computer-readable or processor-readable media may include RAM, ROM, EEPROM, FLASH memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of non-transitory computer-readable and processor-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a non-transitory processor-readable medium and/or computer-readable medium, which may be incorporated into a computer program product. 
     The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present embodiments. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the embodiments. Thus, various embodiments are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.