CA2215535C - Event detector for headsets - Google Patents
Event detector for headsets Download PDFInfo
- Publication number
- CA2215535C CA2215535C CA002215535A CA2215535A CA2215535C CA 2215535 C CA2215535 C CA 2215535C CA 002215535 A CA002215535 A CA 002215535A CA 2215535 A CA2215535 A CA 2215535A CA 2215535 C CA2215535 C CA 2215535C
- Authority
- CA
- Canada
- Prior art keywords
- headset
- microphone
- hookswitch
- telephone
- detector
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/82—Line monitoring circuits for call progress or status discrimination
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/26—Devices for calling a subscriber
- H04M1/53—Generation of additional signals, e.g. additional pulses
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/60—Substation equipment, e.g. for use by subscribers including speech amplifiers
- H04M1/6033—Substation equipment, e.g. for use by subscribers including speech amplifiers for providing handsfree use or a loudspeaker mode in telephone sets
Abstract
An event detector for a headset connected to a telephone, comprising a switch for short circuiting a microphone of the headset and a circuit for detecting a hookswitch flash in the event the duration of the short circuiting of the microphone is greater than a predetermined minimum and less than a predetermined maximum duration.
Description
CA 0221~3~ 1997-09-1~
EVENT DETECTOR FOR HEADSETS
Cross-Reference to Related Application s This is a continuation-in-part of Application serial No. 08/710,746, filed September20, 1996.
Field of the Invention 0 The present invention relates in general to telephone headsets, and more particularly to a circuit for short-circuit detection of a telephone headset forinvoking special features and arbitrating between handset and headset operation in a telephone.
Back~round of the Invention Headsets are useful for hands free telephony in circumstances in which a person requires the use of his or her hands for operation of a computer, switchboard, etc. Headsets are connected to the handset port of a telephone set through an interface box. The interface box allows the user to select whether the headset or the handset is activated. Prior art interface boxes vary greatly in complexity, but most boxes include a headset volume control. Some such boxes are battery operated while others steal current from the microphone bias circuit.
U.S. Patent No. 5,504,812 (Vangarde) discloses a headset and a detector for detecting the presence of the headset and in response activating a hands-free radio telephone. A three-position switch is located in the earpiece of the headset and is connected to the microphone boom to permit user call control by manually rotating the boom. In one embodiment, a further switch and capacitor are added in series with the three-position switch such that in the event the further switch is momentarily opened, a microprocessor connected to the detector implements a CA 0221~3~ 1997-09-1~
telephony hookswitch flash feature whereas, in the event the switch is opened for a sustained period, the detector determines that the microphone has been disconnected and therefore ends the call.
U.S. Patent No. 5,210,791 (Krasik) discloses a telephone headset with detector circuit which utilises an LED in the earpiece to indicated on-line status.
Many PABX and central office telephony features are invoked via a hookswitch flash. Although the above-discussed prior art headsets are capable ofo detecting one or more of on-hook, off-hook and hookswitch flash conditions, they are not capable of doing so in a manner which does not interfere with a call in progress.
Other prior art of interest includes U.S. Patent Nos. 985,169 (Hartnett) s and 3,839,604 (Pardee).
SummarY of the Invention According to the present invention, a circuit is provided for allowing the 20 user to invoke a hookswitch flash signal directly without being required to press a special key on the telephone set, and in a manner which does not interfere with a call in progress. More particularly, according to a preferred embodiment of the invention, a hookswitch flash signal is generated by momentarily depressing a switch connected across the terminals of a headset microphone. Depressing the 25 switch causes a short-circuit across the microphone so as to implement a mutefunction. A circuit is provided for detecting the short-circuit condition and provided the detected short-circuit condition is m~int~ined for a period of timenot less than a predetermined minimum and not greater than a predetermined maximum, a hookswitch flash is confirmed. Otherwise, the call in progress 30 proceeds as usual except that the microphone is muted while the switch is depressed. The circuit according to the present invention provides simplified CA 0221~3~ 1997-09-1~
telephone functionality to the user at low cost, and without a requirement for additional signalling wiring as in prior art systems. Furthermore, the features of the present invention may be added to an existing headset telephone system as a retrofit, without requiring a user to purchase a new headset.
According to another aspect of the present invention, the circuit of the present invention distinguishes between telephone hookswitch and headset hookswitch signals and disables the handset microphone while the headset is in use.
Brief Introduction to the Drawings A detailed description of the preferred embodiment is provided herein below, with reference to the following drawings, in which:
Figure 1 shows a telephone headset with event detection connected to a telephone set in accordance with the present invention;
Figure 2 is a block diagram of a circuit for implementing the detector 20 according to a p~fe,led embodiment of the invention; and Figure 3 comprises Figures 3a, 3b and 3c, and comprises a timing diagram showing timing criteria for detecting a hookswitch flash signal according to thepreferred embodiment.
Detailed Description of the Preferred Embodiment In Figure 1, a standard telephone set 1 is shown with a handset 3 thereof resting in the cradle. The handset 3 is normally connected to the telephone set via 30 a handset port 5 (e.g. RJ-11). In the illustrated embodiment, a headset 7 is also showrl connected to the telephone set 1 via port 5. Headset 7 includes a pair of CA 0221~3~ 1997-09-1~
earpieces 11 and a microphone 13 (e.g. low voltage condenser microphone), in a usual manner.
With reference to Figure 2 in combination with Figure 1, according to the 5 present invention, a switch 15 is connected across the terrninals of microphone 13 such that momentary closure of the switch 15 causes a short circuit across the microphone terminals. Such a feature is known in the art for implementing a microphone mute function.
o Headset microphone bias circuit 17 and handset microphone bias circuit18 provide bias current for the microphone of handset 3 and for microphone 13, respectively. A microphone amplifier 19 is connected differentially to each of the bias circuits 17 and 18 for amplifying the low voltage output signals therefrom.An output of microphone amplifier 19 is connected to a handset microphone input of a phone chip 20 within the telephone set 1. The earpieces 11 of the headset 7 and the earpiece of the handset 3 are connected together and to an output of phone chip 20.
According to the present invention a headset hookswitch detector 21 is connected to the output of headset microphone bias circuit 17. Detector 21 preferably comprises a comparator having inputs connected to a voltage divider in the form of a plurality of series connected resistors between a source of predetermined voltage and ground. In response to a momentary closure of switch 15, a DC voltage level at the input of the comparator will shift. By properly biasing the comparator using well known principles, the comparator detects the DC voltage shift and in response generates a signal (Swk) which is detected by microcontroller 23, as discussed in greater detail below.
A headset present detector 25 is also connected to the output of microphone bias circuit 17 for providing a signal to microcontroller 23 for indicating that headset 7 is connected to the set 1. Since many headsets are CA 0221~3~ 1997-09-1~
connected to telephones via a "quick-disconnect" plug, when the handset 3 is left in its cradle and the headset 7 is disconnected, it is still possible to use thetelephone via the handset operation.
According to an aspect of the present invention, the signal output from detector 25 is also applied to a control input of handset microphone bias circuit 18 via a conversion circuit 27 which translates logic level signals from the detector 25 to levels suitable to disable the microphone bias circuit (e.g. circuit 27 can be a transistor switch, relay contact or other well known disabling circuit).
The telephone hookswitch 29 located in the handset cradle of telephone set 1 is connected to microcontroller 23 for causing generation of an enable handset signal in response to lifting the handset 3 from the cradle for normal operation, without a headset.
For headsets without a mute button, when in the headset mode of operation, a feature key (not shown) of the telephone set 1 may be assigned to function as an offhook indicator such that in response to activating the specialfeature key (instead of lifting handset 3 from its cradle), audio is sent to both the handset 3 and headset 7. However, the signal output from headset present detector 25 disables the microphone of handset 3 to prevent background noise pickup.
In response to momentarily closing switch 15, the microphone 13 is muted and the headset hookswitch signal Swk goes active. With reference to Figure 3, a method is shown by which the microcontroller 23 distinguishes between a hookswitch event caused by activating Swk and a microphone mute.
Specifically, microcontroller 23 samples the headset hookswitch input at a sampling rate "ts" (e.g. lOOms). If the momentary closure of switch 15 is shorter than a predetermined minimum (i.e. ta<tmin (e.g. 400ms in Figure 3b), the closure is deterrnined to be accidental and is therefore ignored. In this manner, the CA 0221~3~ 1997-09-1~
microcontroller 23 performs a switch debouncing function. If the switch closure is sustained for longer than a predetermined maximum duration (i.e. tb>tmax (e.g. 800ms) in Figure 3c), the closure is interpreted as a microphone mute. If the switch 15 is closed for an interval between tmin and tmax, the microcontroller 23 5 interprets the closure as a valid hookswitch flash and in response implements a predetermined special feature.
It is contemplated that the fi~ w~e of microcontroller 23 could be programmed to initiate different features depending on duration of closure or duty 0 cycle of closing of the switch 15. For example, one momentary closure could beused to toggle between parked calls, two closures in rapid succession could be used to initiate music on hold, while a long closure could be used to end a call in progress.
Although the switch 15 is shown located ae the headset 7, it is also contemplated that the switch could be located at a headset interface box (not shown) between the headset 7 and telephone set 1. In either case, provision of the local switch 15 relieves the user from having to reach over to the set in order to force an off-hook condition. It is also contemplated that the switch 15 can be 20 installed as a retrofit to existing headsets in the form of a series device which can dangle from the cable connecting the headset 7 to the telephone set 1 or interface box .
Other embodiments and variations are possible without departing from the 25 sphere and scope of the invention as defined by the claims appended hereto.
EVENT DETECTOR FOR HEADSETS
Cross-Reference to Related Application s This is a continuation-in-part of Application serial No. 08/710,746, filed September20, 1996.
Field of the Invention 0 The present invention relates in general to telephone headsets, and more particularly to a circuit for short-circuit detection of a telephone headset forinvoking special features and arbitrating between handset and headset operation in a telephone.
Back~round of the Invention Headsets are useful for hands free telephony in circumstances in which a person requires the use of his or her hands for operation of a computer, switchboard, etc. Headsets are connected to the handset port of a telephone set through an interface box. The interface box allows the user to select whether the headset or the handset is activated. Prior art interface boxes vary greatly in complexity, but most boxes include a headset volume control. Some such boxes are battery operated while others steal current from the microphone bias circuit.
U.S. Patent No. 5,504,812 (Vangarde) discloses a headset and a detector for detecting the presence of the headset and in response activating a hands-free radio telephone. A three-position switch is located in the earpiece of the headset and is connected to the microphone boom to permit user call control by manually rotating the boom. In one embodiment, a further switch and capacitor are added in series with the three-position switch such that in the event the further switch is momentarily opened, a microprocessor connected to the detector implements a CA 0221~3~ 1997-09-1~
telephony hookswitch flash feature whereas, in the event the switch is opened for a sustained period, the detector determines that the microphone has been disconnected and therefore ends the call.
U.S. Patent No. 5,210,791 (Krasik) discloses a telephone headset with detector circuit which utilises an LED in the earpiece to indicated on-line status.
Many PABX and central office telephony features are invoked via a hookswitch flash. Although the above-discussed prior art headsets are capable ofo detecting one or more of on-hook, off-hook and hookswitch flash conditions, they are not capable of doing so in a manner which does not interfere with a call in progress.
Other prior art of interest includes U.S. Patent Nos. 985,169 (Hartnett) s and 3,839,604 (Pardee).
SummarY of the Invention According to the present invention, a circuit is provided for allowing the 20 user to invoke a hookswitch flash signal directly without being required to press a special key on the telephone set, and in a manner which does not interfere with a call in progress. More particularly, according to a preferred embodiment of the invention, a hookswitch flash signal is generated by momentarily depressing a switch connected across the terminals of a headset microphone. Depressing the 25 switch causes a short-circuit across the microphone so as to implement a mutefunction. A circuit is provided for detecting the short-circuit condition and provided the detected short-circuit condition is m~int~ined for a period of timenot less than a predetermined minimum and not greater than a predetermined maximum, a hookswitch flash is confirmed. Otherwise, the call in progress 30 proceeds as usual except that the microphone is muted while the switch is depressed. The circuit according to the present invention provides simplified CA 0221~3~ 1997-09-1~
telephone functionality to the user at low cost, and without a requirement for additional signalling wiring as in prior art systems. Furthermore, the features of the present invention may be added to an existing headset telephone system as a retrofit, without requiring a user to purchase a new headset.
According to another aspect of the present invention, the circuit of the present invention distinguishes between telephone hookswitch and headset hookswitch signals and disables the handset microphone while the headset is in use.
Brief Introduction to the Drawings A detailed description of the preferred embodiment is provided herein below, with reference to the following drawings, in which:
Figure 1 shows a telephone headset with event detection connected to a telephone set in accordance with the present invention;
Figure 2 is a block diagram of a circuit for implementing the detector 20 according to a p~fe,led embodiment of the invention; and Figure 3 comprises Figures 3a, 3b and 3c, and comprises a timing diagram showing timing criteria for detecting a hookswitch flash signal according to thepreferred embodiment.
Detailed Description of the Preferred Embodiment In Figure 1, a standard telephone set 1 is shown with a handset 3 thereof resting in the cradle. The handset 3 is normally connected to the telephone set via 30 a handset port 5 (e.g. RJ-11). In the illustrated embodiment, a headset 7 is also showrl connected to the telephone set 1 via port 5. Headset 7 includes a pair of CA 0221~3~ 1997-09-1~
earpieces 11 and a microphone 13 (e.g. low voltage condenser microphone), in a usual manner.
With reference to Figure 2 in combination with Figure 1, according to the 5 present invention, a switch 15 is connected across the terrninals of microphone 13 such that momentary closure of the switch 15 causes a short circuit across the microphone terminals. Such a feature is known in the art for implementing a microphone mute function.
o Headset microphone bias circuit 17 and handset microphone bias circuit18 provide bias current for the microphone of handset 3 and for microphone 13, respectively. A microphone amplifier 19 is connected differentially to each of the bias circuits 17 and 18 for amplifying the low voltage output signals therefrom.An output of microphone amplifier 19 is connected to a handset microphone input of a phone chip 20 within the telephone set 1. The earpieces 11 of the headset 7 and the earpiece of the handset 3 are connected together and to an output of phone chip 20.
According to the present invention a headset hookswitch detector 21 is connected to the output of headset microphone bias circuit 17. Detector 21 preferably comprises a comparator having inputs connected to a voltage divider in the form of a plurality of series connected resistors between a source of predetermined voltage and ground. In response to a momentary closure of switch 15, a DC voltage level at the input of the comparator will shift. By properly biasing the comparator using well known principles, the comparator detects the DC voltage shift and in response generates a signal (Swk) which is detected by microcontroller 23, as discussed in greater detail below.
A headset present detector 25 is also connected to the output of microphone bias circuit 17 for providing a signal to microcontroller 23 for indicating that headset 7 is connected to the set 1. Since many headsets are CA 0221~3~ 1997-09-1~
connected to telephones via a "quick-disconnect" plug, when the handset 3 is left in its cradle and the headset 7 is disconnected, it is still possible to use thetelephone via the handset operation.
According to an aspect of the present invention, the signal output from detector 25 is also applied to a control input of handset microphone bias circuit 18 via a conversion circuit 27 which translates logic level signals from the detector 25 to levels suitable to disable the microphone bias circuit (e.g. circuit 27 can be a transistor switch, relay contact or other well known disabling circuit).
The telephone hookswitch 29 located in the handset cradle of telephone set 1 is connected to microcontroller 23 for causing generation of an enable handset signal in response to lifting the handset 3 from the cradle for normal operation, without a headset.
For headsets without a mute button, when in the headset mode of operation, a feature key (not shown) of the telephone set 1 may be assigned to function as an offhook indicator such that in response to activating the specialfeature key (instead of lifting handset 3 from its cradle), audio is sent to both the handset 3 and headset 7. However, the signal output from headset present detector 25 disables the microphone of handset 3 to prevent background noise pickup.
In response to momentarily closing switch 15, the microphone 13 is muted and the headset hookswitch signal Swk goes active. With reference to Figure 3, a method is shown by which the microcontroller 23 distinguishes between a hookswitch event caused by activating Swk and a microphone mute.
Specifically, microcontroller 23 samples the headset hookswitch input at a sampling rate "ts" (e.g. lOOms). If the momentary closure of switch 15 is shorter than a predetermined minimum (i.e. ta<tmin (e.g. 400ms in Figure 3b), the closure is deterrnined to be accidental and is therefore ignored. In this manner, the CA 0221~3~ 1997-09-1~
microcontroller 23 performs a switch debouncing function. If the switch closure is sustained for longer than a predetermined maximum duration (i.e. tb>tmax (e.g. 800ms) in Figure 3c), the closure is interpreted as a microphone mute. If the switch 15 is closed for an interval between tmin and tmax, the microcontroller 23 5 interprets the closure as a valid hookswitch flash and in response implements a predetermined special feature.
It is contemplated that the fi~ w~e of microcontroller 23 could be programmed to initiate different features depending on duration of closure or duty 0 cycle of closing of the switch 15. For example, one momentary closure could beused to toggle between parked calls, two closures in rapid succession could be used to initiate music on hold, while a long closure could be used to end a call in progress.
Although the switch 15 is shown located ae the headset 7, it is also contemplated that the switch could be located at a headset interface box (not shown) between the headset 7 and telephone set 1. In either case, provision of the local switch 15 relieves the user from having to reach over to the set in order to force an off-hook condition. It is also contemplated that the switch 15 can be 20 installed as a retrofit to existing headsets in the form of a series device which can dangle from the cable connecting the headset 7 to the telephone set 1 or interface box .
Other embodiments and variations are possible without departing from the 25 sphere and scope of the invention as defined by the claims appended hereto.
Claims (4)
1. A hookswitch flash detector for a headset connected to a telephone, comprising:
a switch for short circuiting a microphone of said headset, resulting in muting of said microphone;
a circuit for detecting said short circuiting of said microphone and in response generating a hookswitch signal; and a microcontroller for measuring duration of said hookswitch signal and in the event the duration of said hookswitch signal is less than a predetermined minimum duration or longer than a predetermined maximum duration then ignoring said hookswitch signal, and in the event the duration of said hookswitch signal is intermediate said predetermined minimum duration and said maximum duration then interpreting said hookswitch signal as a hookswitch flash for implementing a telephone special feature.
a switch for short circuiting a microphone of said headset, resulting in muting of said microphone;
a circuit for detecting said short circuiting of said microphone and in response generating a hookswitch signal; and a microcontroller for measuring duration of said hookswitch signal and in the event the duration of said hookswitch signal is less than a predetermined minimum duration or longer than a predetermined maximum duration then ignoring said hookswitch signal, and in the event the duration of said hookswitch signal is intermediate said predetermined minimum duration and said maximum duration then interpreting said hookswitch signal as a hookswitch flash for implementing a telephone special feature.
2. The detector of claim 1, further comprising a headset presence detector for detecting connection of said headset to said telephone and in response disabling a handset microphone of said telephone for eliminating background noise pickup.
3. The event detector of claim 1, wherein said switch is integrated into said headset.
4. The event detector of claim 1 wherein said circuit is integrated into said telephone.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US71074696A | 1996-09-20 | 1996-09-20 | |
| US08/710,746 | 1996-09-20 | ||
| US08/839,091 US5832075A (en) | 1996-09-20 | 1997-04-23 | Off-hook detector for headset |
| US08/839,091 | 1997-04-24 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2215535A1 CA2215535A1 (en) | 1998-03-20 |
| CA2215535C true CA2215535C (en) | 2000-06-13 |
Family
ID=27108510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002215535A Expired - Lifetime CA2215535C (en) | 1996-09-20 | 1997-09-15 | Event detector for headsets |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5832075A (en) |
| CA (1) | CA2215535C (en) |
| GB (1) | GB2317783B (en) |
Families Citing this family (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2342798B (en) | 1998-10-16 | 2003-04-16 | Mitel Corp | Telephone headset click-free muting circuit |
| GB2344711B (en) * | 1998-12-11 | 2004-02-25 | Mitel Corp | Click-free muting circuit for headset |
| US6751316B1 (en) | 1998-12-11 | 2004-06-15 | Mitel Corporation | Click-free muting circuit for headset |
| DK199801716A (en) * | 1998-12-23 | 2000-06-24 | Gn Netcom As | Headset |
| GB2350256B (en) | 1999-05-17 | 2001-05-30 | Mitel Corp | Click free mute switch circuit for telephones |
| US6351531B1 (en) | 2000-01-21 | 2002-02-26 | Motorola, Inc. | Method and system for controlling echo cancellation using zero echo path, ringing, and off-hook detection |
| US6735453B1 (en) * | 2000-07-25 | 2004-05-11 | Plantronics, Inc. | Automatic headset hookswitch |
| WO2002039703A2 (en) * | 2000-11-10 | 2002-05-16 | Sybersay Corporation | Apparatus and method for cellular telephone flash/hook switch in wireless headset |
| DE10100386A1 (en) * | 2001-01-05 | 2002-04-25 | Tenovis Gmbh & Co Kg | Switch contact system for headset has switch for producing signal, especially for establishing dialog on connecting line for transmission to mobile telephone for evaluation |
| GB2379831A (en) * | 2001-09-14 | 2003-03-19 | Mitel Knowledge Corp | Signalling between a telephone set and a peripheral device connected to it |
| US20030060242A1 (en) * | 2001-09-27 | 2003-03-27 | Kevin Dotzler | Microphone switchover circuit |
| KR100506283B1 (en) * | 2003-01-14 | 2005-08-05 | 삼성전자주식회사 | Ear-microphone connection apparatus by using a interface connector of portable phone |
| FR2853189B1 (en) * | 2003-03-26 | 2005-08-05 | France Telecom | METHOD FOR MANAGING VOICE COMMUNICATIONS BETWEEN SEVERAL TERMINALS |
| US7299142B2 (en) * | 2003-08-22 | 2007-11-20 | Gateway Inc. | System and method for prevention of accidental activation of portable audio device |
| WO2005096600A1 (en) * | 2004-03-16 | 2005-10-13 | Tunbridge, Craig | Hook status detector for a telephone |
| CN100450240C (en) * | 2005-06-10 | 2009-01-07 | 华为技术有限公司 | Device and method for controlling mobile terminal physical operation |
| US7742758B2 (en) * | 2005-08-19 | 2010-06-22 | Callpod, Inc. | Mobile conferencing and audio sharing technology |
| CN100442892C (en) * | 2006-03-08 | 2008-12-10 | 华为技术有限公司 | Method for preventing mobile terminal earphone keystroke mis-operation and mobile terminal |
| US7707250B2 (en) * | 2006-05-02 | 2010-04-27 | Callpod, Inc. | Wireless communications connection device |
| US8077878B2 (en) * | 2006-07-26 | 2011-12-13 | Qualcomm Incorporated | Low-power on-chip headset switch detection |
| US8103022B2 (en) * | 2006-11-30 | 2012-01-24 | Broadcom Corporation | Method and system for detecting, and controlling power for, an auxiliary microphone |
| US7515071B2 (en) * | 2006-11-30 | 2009-04-07 | Broadcom Corporation | Method and system for audio CODEC voice ADC processing |
| US8861743B2 (en) * | 2008-05-30 | 2014-10-14 | Apple Inc. | Headset microphone type detect |
| KR101785338B1 (en) * | 2011-02-07 | 2017-10-16 | 삼성전자주식회사 | Method and apparatus for reducing current consumption of mobile terminal |
| US8552887B2 (en) * | 2012-01-25 | 2013-10-08 | Garmin International, Inc. | Determining an electrical short in an aviation communication apparatus |
| CN102769697B (en) * | 2012-07-02 | 2015-03-25 | 惠州Tcl移动通信有限公司 | Method and system for preventing false key-pressing caused by earphone inserted into terminal device |
| US10194011B2 (en) * | 2016-09-27 | 2019-01-29 | High Sec Labs Ltd. | Method and apparatus for securing voice over IP telephone device |
| US11606460B2 (en) | 2021-04-07 | 2023-03-14 | High Sec Labs Ltd. | Mutual disabling unit for multiple phones |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US985169A (en) * | 1910-05-31 | 1911-02-28 | Christopher M Hartnett | Telephone-transmitter cut-out. |
| US3839604A (en) * | 1973-01-22 | 1974-10-01 | D Pardee | Telephone transmitter cut-off |
| US4092502A (en) * | 1976-11-03 | 1978-05-30 | Jones Ronald B | Telephone attachment for plug-in headset capability |
| US4313037A (en) * | 1980-06-02 | 1982-01-26 | Rolm Corporation | Telephone station set with improved flash signalling |
| US4387274A (en) * | 1981-06-15 | 1983-06-07 | Gti Corporation | Hook flash signal actuated telephone control device |
| CA1199439A (en) * | 1983-11-22 | 1986-01-14 | Peter Conlon | Telephone hookswitch flasher |
| US4928306A (en) * | 1989-02-28 | 1990-05-22 | International Business Machines Corporation | Dynamically configurable telephone |
| US5210791A (en) * | 1990-12-13 | 1993-05-11 | Michael Krasik | Telephone headset on-line indicator |
| JPH04287545A (en) * | 1991-03-18 | 1992-10-13 | Hitachi Ltd | Portable telephone system |
| US5504812A (en) * | 1994-10-11 | 1996-04-02 | Motorola, Inc. | Headset for use with a radiotelephone |
-
1997
- 1997-04-23 US US08/839,091 patent/US5832075A/en not_active Expired - Lifetime
- 1997-09-15 CA CA002215535A patent/CA2215535C/en not_active Expired - Lifetime
- 1997-09-18 GB GB9719901A patent/GB2317783B/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| GB9719901D0 (en) | 1997-11-19 |
| GB2317783B (en) | 2000-08-02 |
| GB2317783A (en) | 1998-04-01 |
| US5832075A (en) | 1998-11-03 |
| CA2215535A1 (en) | 1998-03-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20170915 |