WO1997023985A1 - Modem loop current detect system to detect an off-hook condition in an extension telephone - Google Patents
Modem loop current detect system to detect an off-hook condition in an extension telephone Download PDFInfo
- Publication number
- WO1997023985A1 WO1997023985A1 PCT/US1996/020117 US9620117W WO9723985A1 WO 1997023985 A1 WO1997023985 A1 WO 1997023985A1 US 9620117 W US9620117 W US 9620117W WO 9723985 A1 WO9723985 A1 WO 9723985A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- telephone
- circuit
- voltage
- optoisolator
- telephone line
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
- G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
- G06K19/0701—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
- G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
- G06K19/073—Special arrangements for circuits, e.g. for protecting identification code in memory
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/0013—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/0013—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers
- G06K7/0021—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers for reading/sensing record carriers having surface contacts
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/0013—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers
- G06K7/0086—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers the connector comprising a circuit for steering the operations of the card connector
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J9/00—Remote-control of tuned circuits; Combined remote-control of tuning and other functions, e.g. brightness, amplification
- H03J9/06—Remote-control of tuned circuits; Combined remote-control of tuning and other functions, e.g. brightness, amplification using electromagnetic waves other than radio waves, e.g. light
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/22—Modifications for ensuring a predetermined initial state when the supply voltage has been applied
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/78—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
- H03K17/795—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled controlling bipolar transistors
- H03K17/7955—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled controlling bipolar transistors using phototransistors
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/738—Interface circuits for coupling substations to external telephone lines
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/738—Interface circuits for coupling substations to external telephone lines
- H04M1/7385—Programmable or microprocessor-controlled
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/738—Interface circuits for coupling substations to external telephone lines
- H04M1/74—Interface circuits for coupling substations to external telephone lines with means for reducing interference; with means for reducing effects due to line faults
- H04M1/745—Protection devices or circuits for voltages surges on the line
-
- 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
Definitions
- the subject invention concerns generally concerns the field of telephone line monitoring circuits.
- Modern satellite television systems such as the RCA DSS® system, manufactured by Thomson Consumer Electronics. Inc., Indianapolis, Indiana, include circuitry for automatically calling a predetermined telephone number to report the billable specifics regarding the use of the customer's integrated receiver decoder (IRD).
- IRD integrated receiver decoder
- Such billing is necessary, of course, because the user receives programming by subscribing to one or more of several program providers.
- IRD integrated receiver decoder
- Unfortunately there is no time of day at which the IRD is guaranteed access to the telephone line, because the user may be placing a call, literally anytime (one cannot schedule emergencies, for example). It is desirable, therefore to be able to detect a condition in which the user picks up an extension phone, in order that the IRD may release the line to the user.
- a telephone line monitoring circuit uses an optoisolator to convert the telephone line current to a voltage which is applied to the input of an A/D converter.
- the A/D values are coarse values representing telephone line current.
- the A/D is sampled at a predetermined interval to identify changes introduced by the telephone company central office, and to take those changes into account when deciding if an extension telephone has gone off- hook.
- the line current divides between the extension telephone and the IRD modem, and such change is detected.
- FIGURE 1 shows telephone line monitoring circuitry suitable for use with the invention
- FIGURE 2 shows a table of line current values and A/D readings useful in understanding the invention.
- FIGURE 3 shows an alternate embodiment of a telephone line monitoring circuit in accordance with the invention.
- a diode bridge arrangement BR1 is coupled to a telephone network (not shown), via TIP and RING terminals, for providing communication to and from consumer electronics equipment, the relevant portions of which are illustrated in FIGURE 1.
- a Sidactor®, manufactured by TECCOR Inc., (a bidirectional diac) S I is coupled across the plus and minus terminals of bridge BR1 to protect the circuitry further coupled to the bridge.
- a Sidactor® is a protection device having an operational characteristic such that, after a breakover voltage is achieved, as the current through the device goes up, its impedance goes down. Its function in the arrangement of FIGURE 1 is to limit the voltage developed across OPTO 1.
- OPTOl is a darlington optoisolator, and is used as an electronic equivalent of a "hook- switch" for connecting the equipment to the telephone network for placing a call.
- OPTO 1 operates under control of a system control microcomputer ( ⁇ C) 1 10.
- ⁇ C system control microcomputer
- microcomputer controller, and “microprocessor”, as used herein, are equivalent. It is also recognized that the control function of microcomputer 110 may be performed by an integrated circuit especially manufactured for that specific purpose (i.e., a "custom chip"), and the term
- Microcomputer 1 10 includes a central processing unit (CPU) 112, a program memory (ROM) 116, and stores short term data in a random-access memory (RAM) 114.
- RAM 1 14 may be either internal to, or external to, microprocessor 1 10, and may be of either the volatile or non-volatile type.
- RAM is also intended to include electrically-erasable programmable read only memory (EEPROM).
- EEPROM electrically-erasable programmable read only memory
- Optoisolator OPTOl couples signals to and from a modem 100 via an isolation transformer Tl .
- the telephone company loop current present in the primary winding of transformer Tl is also applied via a resistor Rl to a second optoisolator OPT02.
- OPT02 converts the loop current into an output voltage developed across its emitter resistor R3.
- the output voltage is applied across an arrangement comprising resistor R4 and diode D4, and is also applied to the input of an A/D converter 1 18 included within microcomputer 110.
- A/D converter 1 18 may also be located outside of microcomputer 1 10, and coupled thereto.
- resistor R4 and diode D4 are interesting in that resistor R4 is decoupled from the circuit until the forward voltage of diode D4 is met. At that point resistors R3 and R4 are essentially in parallel. As noted earlier, one cannot count on the line voltage provided by the telephone company to be any particular value. In fact, it may cover a wide range of values. In addition, the line monitoring circuitry must be designed to ensure proper operation at the central office under all conditions. One constraint applied to this design is that the circuitry must present an impedance to the telephone network of no more than 300 ohms at 20 milliamps (ma) DC.
- the input impedance be such that it develops no more than 6 volts across it at a current of 20 ma.
- a series connection of diodes DI, D2, D3, is connected across resistor Rl and optoisolator OPT02.
- Diodes DI , D2, D3 is connected across resistor Rl and optoisolator OPT02.
- D2, and D3 limit the voltage across OPT02 to a value which ensures that OPT02 will not be destroyed under high telephone line voltage conditions.
- the voltage drop across diodes DI , D2, and D3 changes in accordance with the current through them.
- Resistor R2 serves to lower the voltage across the series connection of diodes DI, D2, and D3 during low current (i.e., 20 ma) operation. This ensures proper operation of central office pulse dialing under low current conditions.
- the telephone line loop current is continually monitored at regular intervals.
- FIGURE 2 shows a table of values of loop current and corresponding carrier detector output voltages, and the recommended trigger point for making the decision as to whether or not an extension phone was picked up. It should be noted that if the loop current is relatively low (18 ma or less) then detection of extension pickup by monitoring the voltage becomes unreliable. However, the Federal Communications Commission (FCC) has specified the minimum long loop current to be provided by the telephone service provider to be 23 ma.
- FCC Federal Communications Commission
- the circuit of FIGURE 1 still provides a reliable trigger point with a loop current of as little as 20 ma (3 ma below the minimum allowable current). It is also noted that the current provided by the telephone company can be as high as 120 ma.
- the subject invention uses this recognition to provide a plurality of "trigger points" (specific voltage levels) which accommodate this wide range in order to reliably indicate that an extension phone has been picked up.
- FIGURE 3 shows an alternate embodiment of the invention in which diodes DI , D2, and D3, and resistor R2, have been replaced by a transistor arrangement comprising transistor
- R301 (and Rl of FIGURE 1) is preferably 560 ohms.
- R303 (and R3) is preferably 15 kilohms.
- R304 (and R4) is preferably 1.5 kilohms.
- a typical value for resistor R305 and resistor R306 (and for R2 of FIGURE 1 ) is 68 ohms. This value is important in that if a relatively higher resistance value is chosen, then a voltage will be developed which is greater than the previously mentioned 6 volts at 20 ma input current.
- Emitter resistor R307 is preferably 7.5 ohms.
- Q301 may be a commonly- available 2N3904 transistor.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Artificial Intelligence (AREA)
- Signal Processing (AREA)
- Computer Security & Cryptography (AREA)
- Electromagnetism (AREA)
- General Engineering & Computer Science (AREA)
- Telephonic Communication Services (AREA)
- Interface Circuits In Exchanges (AREA)
- Emergency Protection Circuit Devices (AREA)
- Power Sources (AREA)
- Devices For Supply Of Signal Current (AREA)
- Selective Calling Equipment (AREA)
- Telephone Function (AREA)
- Optical Communication System (AREA)
- Sub-Exchange Stations And Push- Button Telephones (AREA)
- Noise Elimination (AREA)
- Monitoring And Testing Of Exchanges (AREA)
- Details Of Connecting Devices For Male And Female Coupling (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
- Communication Control (AREA)
- Air Bags (AREA)
- Filters And Equalizers (AREA)
- Elimination Of Static Electricity (AREA)
- Credit Cards Or The Like (AREA)
- Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP96944437A EP0868805B1 (en) | 1995-12-22 | 1996-12-18 | Modem loop current detect system to detect an off-hook condition in an extension telephone |
DE69620023T DE69620023T2 (en) | 1995-12-22 | 1996-12-18 | MODEM LOOP CURRENT DETECTION SYSTEM FOR DETECTING A LOSS OF A LOOP IN A SUB-INTERCOM |
US09/091,314 US6134321A (en) | 1995-12-22 | 1996-12-18 | Modem loop current detect system to detect an off-hook condition in an extension telephone |
BRPI9612170-0A BR9612170B1 (en) | 1995-12-22 | 1996-12-18 | modem line current detection system to detect off-hook condition on extension telephone. |
AU14244/97A AU1424497A (en) | 1995-12-22 | 1996-12-18 | Modem loop current detect system to detect an off-hook condition in an extension telephone |
JP52377097A JP4044962B2 (en) | 1995-12-22 | 1996-12-18 | Telephone line monitor circuit |
CA002240287A CA2240287C (en) | 1995-12-22 | 1996-12-18 | Modem loop current detect system to detect an off-hook condition in an extension telephone |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US917895P | 1995-12-22 | 1995-12-22 | |
US60/009,178 | 1995-12-22 | ||
GB9600002.1 | 1996-01-02 | ||
GBGB9600002.1A GB9600002D0 (en) | 1996-01-02 | 1996-01-02 | Receiver for compressed television information |
GBGB9613608.0A GB9613608D0 (en) | 1996-06-28 | 1996-06-28 | 40mhz VCXO and loop filter for digital symbol lock timing for high speed modems |
GB9613608.0 | 1996-06-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997023985A1 true WO1997023985A1 (en) | 1997-07-03 |
Family
ID=27268058
Family Applications (5)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1996/020514 WO1997023989A1 (en) | 1995-12-22 | 1996-12-17 | An automatic subscriber callback system |
PCT/US1996/019928 WO1997023840A1 (en) | 1995-12-22 | 1996-12-17 | Fault detection and modification circuit |
PCT/US1996/019932 WO1997023987A1 (en) | 1995-12-22 | 1996-12-17 | A telephone equipment protection circuit |
PCT/US1996/019929 WO1997023954A1 (en) | 1995-12-22 | 1996-12-17 | Electrical isolation between ir receiver and further electronic circuits |
PCT/US1996/020117 WO1997023985A1 (en) | 1995-12-22 | 1996-12-18 | Modem loop current detect system to detect an off-hook condition in an extension telephone |
Family Applications Before (4)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1996/020514 WO1997023989A1 (en) | 1995-12-22 | 1996-12-17 | An automatic subscriber callback system |
PCT/US1996/019928 WO1997023840A1 (en) | 1995-12-22 | 1996-12-17 | Fault detection and modification circuit |
PCT/US1996/019932 WO1997023987A1 (en) | 1995-12-22 | 1996-12-17 | A telephone equipment protection circuit |
PCT/US1996/019929 WO1997023954A1 (en) | 1995-12-22 | 1996-12-17 | Electrical isolation between ir receiver and further electronic circuits |
Country Status (12)
Country | Link |
---|---|
US (1) | US6442255B1 (en) |
EP (5) | EP0868807A1 (en) |
JP (5) | JP4452330B2 (en) |
KR (5) | KR100422229B1 (en) |
CN (5) | CN1126056C (en) |
AU (5) | AU1467397A (en) |
BR (3) | BR9612168A (en) |
CA (1) | CA2240287C (en) |
DE (3) | DE69604596T2 (en) |
HK (1) | HK1018651A1 (en) |
MX (5) | MX9805007A (en) |
WO (5) | WO1997023989A1 (en) |
Cited By (4)
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EP0951170A1 (en) * | 1998-04-17 | 1999-10-20 | THOMSON multimedia | Modem including a device for detecting the busy state of a telephone line |
WO1999065220A1 (en) * | 1998-06-11 | 1999-12-16 | Conexant Systems, Inc. | System and method for detecting telephone line events |
WO2007030945A1 (en) * | 2005-09-15 | 2007-03-22 | Tyco Safety Products Canada Ltd. | Telephone line communication interface |
WO2007073595A1 (en) * | 2005-12-29 | 2007-07-05 | Tyco Safety Products Canada Ltd. | Direct access arrangement device |
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US20020112241A1 (en) * | 2001-02-14 | 2002-08-15 | Cocchi Ronald P. | Internet service provider callback for satellite systems |
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- 1996-12-17 EP EP96942968A patent/EP0868807A1/en not_active Ceased
- 1996-12-17 WO PCT/US1996/020514 patent/WO1997023989A1/en active IP Right Grant
- 1996-12-17 JP JP52384297A patent/JP4452330B2/en not_active Expired - Lifetime
- 1996-12-17 AU AU14673/97A patent/AU1467397A/en not_active Abandoned
- 1996-12-17 US US09/091,335 patent/US6442255B1/en not_active Expired - Lifetime
- 1996-12-17 WO PCT/US1996/019928 patent/WO1997023840A1/en active IP Right Grant
- 1996-12-17 JP JP52373197A patent/JP4077877B2/en not_active Expired - Fee Related
- 1996-12-17 BR BR9612168A patent/BR9612168A/en not_active IP Right Cessation
- 1996-12-17 WO PCT/US1996/019932 patent/WO1997023987A1/en not_active Application Discontinuation
- 1996-12-17 WO PCT/US1996/019929 patent/WO1997023954A1/en active IP Right Grant
- 1996-12-17 AU AU12908/97A patent/AU715450B2/en not_active Expired
- 1996-12-17 BR BR9612176A patent/BR9612176A/en not_active Application Discontinuation
- 1996-12-17 AU AU14199/97A patent/AU1419997A/en not_active Abandoned
- 1996-12-17 DE DE69604596T patent/DE69604596T2/en not_active Expired - Lifetime
- 1996-12-17 CN CNB961999780A patent/CN1166158C/en not_active Expired - Fee Related
- 1996-12-17 KR KR10-1998-0704622A patent/KR100422229B1/en not_active IP Right Cessation
- 1996-12-17 KR KR10-1998-0704618A patent/KR100454013B1/en not_active IP Right Cessation
- 1996-12-17 EP EP96945262A patent/EP0868810B1/en not_active Expired - Lifetime
- 1996-12-17 JP JP09523730A patent/JP2000516358A/en active Pending
- 1996-12-17 CN CN96180025A patent/CN1097878C/en not_active Expired - Lifetime
- 1996-12-17 EP EP96943749A patent/EP0868704B1/en not_active Expired - Lifetime
- 1996-12-17 EP EP96944374A patent/EP0868781B1/en not_active Expired - Lifetime
- 1996-12-17 JP JP52372997A patent/JP3573350B2/en not_active Expired - Fee Related
- 1996-12-17 CN CNB961999799A patent/CN1166162C/en not_active Expired - Lifetime
- 1996-12-17 KR KR10-1998-0704617A patent/KR100408983B1/en not_active IP Right Cessation
- 1996-12-17 DE DE69636523T patent/DE69636523T2/en not_active Expired - Lifetime
- 1996-12-17 AU AU11519/97A patent/AU1151997A/en not_active Abandoned
- 1996-12-17 KR KR10-1998-0704619A patent/KR100490016B1/en not_active IP Right Cessation
- 1996-12-18 CN CN96199239A patent/CN1095269C/en not_active Expired - Lifetime
- 1996-12-18 AU AU14244/97A patent/AU1424497A/en not_active Abandoned
- 1996-12-18 EP EP96944437A patent/EP0868805B1/en not_active Expired - Lifetime
- 1996-12-18 CA CA002240287A patent/CA2240287C/en not_active Expired - Fee Related
- 1996-12-18 DE DE69620023T patent/DE69620023T2/en not_active Expired - Lifetime
- 1996-12-18 KR KR10-1998-0704623A patent/KR100419331B1/en not_active IP Right Cessation
- 1996-12-18 BR BRPI9612170-0A patent/BR9612170B1/en not_active IP Right Cessation
- 1996-12-18 JP JP52377097A patent/JP4044962B2/en not_active Expired - Fee Related
- 1996-12-18 WO PCT/US1996/020117 patent/WO1997023985A1/en active IP Right Grant
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1998
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1999
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EP0951170A1 (en) * | 1998-04-17 | 1999-10-20 | THOMSON multimedia | Modem including a device for detecting the busy state of a telephone line |
FR2777727A1 (en) * | 1998-04-17 | 1999-10-22 | Thomson Multimedia Sa | MODEM COMPRISING A DEVICE FOR DETECTING THE OCCUPANCY OF A TELEPHONE LINE |
US6292546B1 (en) | 1998-04-17 | 2001-09-18 | Thomson Licensing, S.A. | Modem including a device for detecting the busy state of a telephone line |
WO1999065220A1 (en) * | 1998-06-11 | 1999-12-16 | Conexant Systems, Inc. | System and method for detecting telephone line events |
US6104791A (en) * | 1998-06-11 | 2000-08-15 | Conexant Systems, Inc. | System and method for performing telephone line-in-use detection, extension pick-up detection, and remote hang-up detection in a modem |
WO2007030945A1 (en) * | 2005-09-15 | 2007-03-22 | Tyco Safety Products Canada Ltd. | Telephone line communication interface |
WO2007073595A1 (en) * | 2005-12-29 | 2007-07-05 | Tyco Safety Products Canada Ltd. | Direct access arrangement device |
US7835516B2 (en) | 2005-12-29 | 2010-11-16 | Tyco Safety Products Canada Ltd. | Direct access arrangement device |
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