MXPA98002201A - Telephones or coordination additives in the same ci - Google Patents

Abstract

The present invention relates to when two or more telephone sets are in use in the same cycle of the subscriber, their activities can not be detected or monitored properly by the central office switch. The present invention provides a method of and apparatus for coordinating activities, so that the caller of the waiting call ID or the caller ID off-hook or other service characteristics, can work even if there are extensions off-hook in the same cycle. The invention ensures that only one device among a plurality of dropped devices responds to the switch.

Description

TELEPHONES OR COORDINATION ATTACHMENTS IN THE SAME CYCLE Field of the invention The invention relates in general to the transmission of signals in a bifilar circuit of the subscriber between CPEs (hypothetical equipment of the client) and a switch in a CO (central switching office) . In particular it addresses a situation where a plurality of CPEs are connected to a bifilar circuit of the subscriber. Background of the Invention In addition to the customer payload signals such as voice, data or other forms of information, a bifilar circuit of the subscriber carries several control signals, which are exchanged between a CPE and a switch in a CO. These control signals (simply called, local signal or signal transmission) are generated according to a widely accepted signal transmission protocol and performs functions such as call signal, detect busy line conditions, at rest or off hook , and so on. Recently, many more functions have been added to existing ones in order to provide new types of customer services. These new services include, call answer, call waiting, call in advance and caller identification, to name a few.

CLASS (services of transmission of signals from the local area to the client) is a signal transmission protocol that is widely accepted by the industry today, to provide this wide range of services. This will be described in detail below as an example. The control data format in CLASS is serial, binary and asynchronous. The modulation is FSK speech band, which uses 1200 and 2200 HZ for logic 1 and 0 respectively. Figure 1 shows fields of the CLASS data format. Each data word consists of an 8-bit byte, each word of data is preceded by a start bit (interval) and followed by a stop bit (mark), a total of 10 bits in a word. The transmission of any 8-bit character is supported in a message word. The alert signal consists of 180 bits (in transmission at rest) and 80 bits (in off-hook transmission) of continuous marking. The channel pick-up signal occurs only during idle transmission. It consists of 300 continuous bits of mark and alternative interval, started with the interval and finished with the mark. The transmission speed is 1200 Baud. SCWID (Spontaneous Call Waiting Indication) or Call Waiting Caller ID or Call Waiting Caller ID, is a technique of signaling to the subscriber the identity of a call waiting caller while the subscriber is off hook at another call. The subscriber can then choose to speak with the call waiting caller when making a connection pulse or "Link". This feature is one of many services, which are contemplated and implemented when using CLASS. In this application, due to the lack of an appropriate terminology, SCWID is used in each part, to indicate these characteristics, which use the transmission of off-hook signals. U.S. Patent No. 5,263,084 issued November 16, 1933 to Chaput and Cois, describes the operation of a typical off-hook signal transmission technology. Briefly, the protocol is as follows: When a caller is on hold, the office switch sends a SAS tone (alert signal to the subscriber) and then a CAS tone (alert signal to the client) in voice band . The subscriber's device detects the CAS tone and if it is able to receive additional CLASS or other information, an ACK (acknowledgment) signal (a DTMF tone) is returned to the switch. The switch then sends the FSK data packet containing the caller identity of the call waiting or any other information in the data format described above. During the time from the CAS to the end of the FSK data packet the subscriber's apparatus decreases the intensity of the RX and TX paths to the subscriber, so that they do not possibly hear or corrupt the data transport mechanisms. BellCore, who established a procedure for CLASS, recommends that the subscriber apparatus equipped with SCWID (telephone device) should verify if any of the extension extensions exist in the cycle before sending the ACK back to the switch after receiving a CAS. If the switch does not receive an ACK from the subscriber's device within a predetermined period of time (eg, maximum 100 ms), it will not send FSK data containing the caller ID of the call waiting. In the known installation, the subscriber apparatus equipped with SCWID and the attachments monitor the DC conditions in the cycle and if an extension is detected then they do not send an ACK to the switch. This means that the Caller ID of the call waiting or the Caller ID of the off-hook or another transmission of off-hook signals does not work if an extension is off-hook. It should be noted that although the description, which follows, mainly deals with FSK, SC ID (off-hook caller ID) signals, which are exchanged between the terminal and the office switch, after which an ACK signal can be used. to transmit different information in addition to the caller ID for a variety of other services. OBJECTS OF THE INVENTION It is therefore an object of the invention to provide a method and apparatus for coordinating activities so that the transmission of off-hook signals can work even when there are extensions off-hook in the same cycle. It is a further object of the invention to provide a method of and apparatus for assigning one of the CPEs to respond to the transmission of off-hook signals from the switch. It is still an object of the invention to provide a method of and apparatus for dynamically allocating one of the CPEs to respond to the transmission of off-hook signals from the switch. SUMMARY OF THE INVENTION Briefly stated, the invention resides in a telephone cycle, which contains a plurality of telephone sets at one end and a telephone switch at the other end. In one aspect, the invention is directed to a method for recognizing a customer alert signal sent by a telephone switch when the telephone cycle is in the condition, in which at least one telephone set of the plurality of telephone sets is located. off hook. The method comprises steps of assigning a first telephone set to transit to a off-hook state as a master between the plurality of telephone sets and the remaining sets as subordinates during a telephone call and detecting the alert signal of the customer in the master. The method further includes a step of responding appropriately to the customer alert signal depending on the status of one or more remaining telephone sets to indicate that the plurality of telephone sets are ready to receive off-hook signals from the telephone switch. According to another aspect, the invention is directed to a telephone device to be connected to a telephone switch in the manner of a telephone cycle. The telephone apparatus of the invention includes a circuit for monitoring the DC condition of the telephone circuit to determine if one or more telephone sets are in off-hook state between a plurality of telephone sets, which are connected to the telephone cycle and a circuit of demodulation to detect a customer alert signal sent by the switch connected to the telephone cycle when the telephone cycle is in off-hook condition. The telephone apparatus further includes a line operation circuit for sending a recognition signal in response to the customer alert signal, and a controller for assigning a telephone device as a master if it is the first telephone device to transit to the state of off-hook between the plurality of telephone sets and to allow the line operation circuit if the telephone set is assigned as a master. Brief Description of the Drawings Figure 1 shows fields of the CLASS data format; Figure 2 shows typical DC conditions of a subscriber line when one or more telephone sets are off-hook at different times; Figure 3 is a functional block diagram of the invention according to one embodiment; Figure 4 graphically illustrates DC conditions for some typical cases, in which changes in the line voltage are placed on the same time scale; Figure 5 graphically shows gradual changes of the voltage over time; Figure 6 shows the operation of the coordination of impulses according to a modality; Figure 7 shows the line voltage, when more than one extension is off-hook and coordinate the impulses according to another modality; Figure 8 is a machine in the idle state of Parallel Direction Detection (PSD); and Figure 9 is a machine in the off-state state of Parallel Direction Detection (PSD). Detailed Description of the Preferred Modes of the Invention As described above, in the known installation, a subscriber apparatus monitors the DC conditions in the cycle and if an extension in use is detected, when they receive a SCWID signal (for example, CAS), they do not send an ACK to the switch, even though both devices are equipped with the SC ID capability or transmission of similar off-hook signals. This means that the caller ID of the call waiting or the caller ID of the off-hook or such features do not work if an extension is off-hook. Figure 2 shows typical DC conditions of a subscriber line when one or more telephone sets are off-hook at different times. Normally, the line voltage is somewhere above 20V (voltage A), when there are no off-hook devices (inactive line), depending on the battery (usually either 24V or 48V, in the latter case, voltage A is approximately 35V). When a single device is off-hook, the voltage drops significantly to voltage B (typically about 10 volts). If another device is off-hook (1 EIU, extension in use), the voltage drops more, however not as drastically as when the initial device was found off-hook (ie, the% change in line voltage is much less) . This voltage is C and is typically approximately 7 volts. Each device with an additional extension that is off-hook on the same line lowers the line voltage even more, but by continuously smaller amounts. In this description, these DC voltages (when two or more devices are off-hook) are collectively called EIU. It is further noted that all downloadable compatible equipment is described herein as appliances with hooked extension or simply appliances. It should also be noted that the above description deals with the voltage changes, but the current in the cycle exhibits changes similar to those of the voltage. In certain implementations, the current is monitored instead of the voltage. The invention detects the presence of two or more apparatuses in use and ensures that all the devices coordinate their response to signals in the voice band coming from the office switch so that the various services to the client can be carried out. Figure 3 is a functional block diagram of the invention according to one embodiment. It should be noted herein that the block diagram includes only functions, which relate to the invention. These functions can be built into an add-on to be added to an existing guest device or can be built as part of a customer's hypothetical equipment. It should also be noted that the elements, which perform these functions in the diagram, can therefore be independent elements in a reprogrammed host element or elements. In the figure, the DC voltage of a telephone line 10 is monitored by a line voltage monitoring module 12. The module measures the DC voltage when compared to a reference voltage and uses an analog-to-digital converter ( ADC) to produce digital signals to indicate non-extension in use (NEIU), extension in use (EIU), at rest, off-hook, etc. The ADC is read once every 20ms in this mode, and a microcontroller 14 drives the SM of parallel address detection (state machine) with the reading of the line voltage. The actual reading of the ADC is made over 16 counter switch calls. This interrupts every 0.25ms and therefore takes approximately 4ms to read the ADC. The state machine will be described in detail later. The demodulation module 16 includes a demodulator, which demodulates the FSK data in CLASS message, and also includes a CAS detector, which detects the CAS tone. When the demodulation module receives FSK data, it sends them accordingly to a microcontroller 14. When the apparatus is idle and none of the extensions is in use, the demodulator is always enabled and the microcontroller 14 is ready to decode a CLASS message. The demodulator is disabled during the discontinuity of the call signal and each time an extension is used again. When an extension is in use, the CAS tone detector is enabled because a CAS tone is expected to indicate that the SC ID data is close. After the detection of a CAS tone, for example 150 ms later, the microcontroller allows either the demodulator to decode the FS ID data of SC ID or instructions to an online operation module 18 to generate an ACK signal. , depending on whether an extension is in use or not. In addition, to generate an ACK signal, the online operation module 18 performs a DC interruption, a decrease in the intensity of the speech path, etc. The figure also includes additional modules of EEPROM 20, which store all the necessary programmed functions and the combination of key / display 22. According to one embodiment of the invention, by following a set of pre-programmed rules, telephone sets or devices equipped with SCWID can coordinate their activities so that the caller ID of the call waiting (caller ID off-hook) or other services can work and maintain the recommendations of BellCore even when there are extendable extensions of compatible types. The rule set ensures that there is a device, which generates a tone of the ACK signal since the office switch can not detect it properly if there is more than one device that responds with an ACK signal. When multiple devices are off-hook, each must be assigned as a teacher, subordinate or reserve teacher. When an SCWID signal (for example CAS) is received from the office switch, only the master will recognize it, when generating an ACK signal. Subordinates will never generate an ACK signal. The teacher is defined as the device that worked off-hook first. All devices monitor the DC cycle conditions. Figure 4 illustrates these DC conditions for some typical cases, in which changes in the voltage line are placed on the same time scale. If there are no other extensions off-hook when a device is off-hook, then this device is the master. Otherwise the device is a subordinate. The teacher clears his state of master when he is at rest. The states of the master and subordinate are assigned dynamically on a per-call basis. Rules for Subordinates i) If a device is off-hook and the extension in use is active, then that device is a subordinate. The status of the subordinate is assigned dynamically on a per-call basis. Any device can be a subordinate device. ii) When subordinates detect a CAS, they must remove their DC terminations and decrease the intensity of the voice paths within approximately 20 ms. They should not respond with an ACK. iii) They must monitor the conditions of the AC cycle and receive and display the FSK data that contains the identity of the callers of the waiting call or other information. iv) In the successful reception of FSK data or a delay, the subordinates will re-establish their terminations of DC and voice trajectories. Rules for the Master i) When a teacher detects a CAS, he must decrease the intensity of his voice path and measure the DC conditions in the cycle. If there is no extension present (except the teacher himself), the teacher will respond with an ACK. The master recognizes the exchanges of CAS and FSK data that take place. This is shown by line A in figure 4. In this case the master does not detect any EIU because the voltage line did not change when a CAS was detected. Ii) All unhooked devices equipped in a similar way will be subordinated and will have to withdraw their DC terminations and decrease the intensity of their voice trajectories. The master detects an EIU due to changes in the line voltage at 30. This is illustrated by line B of figure 4. iii) All unattached sections not equipped or off-hook not compatible will not have removed their DC terminations. The master detects this condition and will not respond with an ACK. Rules for the Reserve Master (BUM) i) If the master disconnects a call when there are two or more subordinates remaining, a reserve master (BUM) must respond with an ACK. The BUM is dynamically assigned to the last successful ACK. A BUM can be at rest or off-hook. The BUM will only be ACK if there is no teacher. This can be determined since the master never withdraws his DC termination from the duration of the call. ii) A BUM is defined as the last unit that successfully responded with an ACK. After a successful SC ID call, all units update their BUM status. The unit, which responds with an ACK, becomes the BUM. All units, which received data from SC ID, but did not respond with an ACK, clear their status as BUM. The BUM can be at rest or off-hook. For this reason the condition of BUM is not established or re-established when an appliance is off-hook or at rest. iii) If a resting BUM detects a CAS, it checks the DC conditions in the cycle. If there are no extensions present, the backup master will take the line to reapply the DC termination and respond with an ACK. If a dropped BUM detects a CAS, it checks the DC conditions on the line, if there are no extensions except the same one present, it will also reapply the DC termination and respond with an ACK. The off-hook BUM will then establish its master indication. Line C in Figure 4 illustrates these BUM and subordinate operations. A large increase 38 indicates the withdrawal of DC terminations by the BUM and all subordinates. When the BUM returns to take the line when applying its DC termination, which again lowers the line voltage. iv) All unhooked devices equipped in a similar way will be subordinated and will have to remove their DC terminations and decrease the intensity of their voice trajectories. It should be noted that lines A, B, and C of Figure 4 show small voltage increases 32, 34, and 36 before the ACK indicate the difference in the DC characteristics of the DC termination circuit when one is connect This is because, when the decrease in intensity or other functions are to be performed, it is possible that a circuit with a separate DC termination could be inserted instead of an existing one, v) If there are devices in the cycle, which do not are equipped with SCWID capability and are currently off-hook, they will not have to remove their DC terminations. In this case, the reserve master will not respond with an ACK. vi) This installation also decides the case where the first unit off-hook is an unsupported SCWID device, two or more subordinates are off-hook and then the unsupported SCWID device disconnects the call. Also, if the first device off-hook is not an SCWID device, the master will be assumed by other devices even when they can not generate an ACK tone. Figure 4 illustrates this via line D. Other complications appear if there are non-compatible SC ID devices incorporated as a subordinate in a call. The master must detect this and must not respond with an ACK signal (to maintain the ACK / FSK without decreasing the intensity from the deformation user). This is resolved since all subordinates remove their DC terminations when a CAS is detected. Since unsupported SCWID devices will not remove the DC termination, the teacher can search for an EIU after a CAS is detected. If the EIU is true then the teacher will not respond with an ACK. If the EIU is not true then the teacher will respond with an ACK. When an appliance is off-hook and begins to monitor the line voltage, it is not guaranteed to remain at a fixed level. As seen in Figure 5, you can actually crawl up and down by a significant amount, in other words the EIU threshold floats. This gradual change must be monitored and compensated. A significant drop in line voltage is indicative of an extension in use. When this fall occurs, the value that triggered it is saved. The line voltage must rise above this value before the device activates any extension in use. The microcontroller and the EEPROM can be appropriately programmed to adjust such drag so that the threshold values would vary appropriately. As described above, if there are two or more devices that are in use in the cycle, a connection pulse (line interruption) is not possible by any of the devices in use, because the remaining devices in use maintain the DC connection. According to another embodiment, the invention detects the presence of two or more apparatuses in use and allows any of the apparatuses to perform the connection impulse. In summary, extension devices in use are detected by monitoring falls and changes in line voltage (called EIU, extension-in-use) and when one of the devices performs the connection pulse, all devices in use they coordinate their connection impulses so that the office switch is able to detect an appropriate connection impulse. In one embodiment, the line operation circuit shown in Figure 3 includes the functionality of the connection or link pulse. Figure 6 shows this operation according to a modality. Under a set of pre-established rules, one of the devices, which wishes to perform a connection pulse, becomes the impulse master. All other devices are made subordinate impulse. The pulse master is the device, in which a key called the PULSE key (also called the link key or the call waiting option key) is pressed to perform a coordinated connection pulse. It should be noted herein that this inventive feature can be incorporated as part of a telephone device equipped with SCWID or it can be made as an SCWID add-on apparatus, which is to be attached to an existing guest apparatus. Therefore in the case of the attachment device, it can become the impulse master if the LINK or PULSE key is pressed on the host device or if its own LINK or PULSE key is pressed. The pulse master performs a synchronization or pre-link pulse of approximately 140ms duration, followed by an inter-link pause of approximately 300ms duration and then a 300-1500ms line interruption. In 50, the EIU disappears for the duration of a pre-link approximately 140 ms, then reappears by approximately 440ms in 52. If this happens, when the EIU disappears a second time in 54, all the devices in use will then be linked also at 56, generating a true line interruption. The first impulse, which can be called a link or pre-link sub-signal, signals the subordinate devices that should be sent quickly. The second impulse generated by the master is regulated to coincide with an impulse generated in all the subordinates. The impulse subordinates monitor the DC conditions in the cycle. If they observe a predetermined increase in the cycle voltage that lasts approximately 140 ms followed by approximately 440 ms of the original cycle conditions (inter-link) followed by a rising cycle voltage edge, they perform their own pulse, which coincides with the second impulse made by the teacher. In this way all extensions perform a simultaneous pulse and the switch will actually observe a 600 ms interval of zero cycle current. This procedure also works when there are more than one EIU. Referring to Fig. 7, when an extension is in use, there is a remote link threshold value that is 1/16 more than the off-hook line voltage present. The figure shows two threshold values, which are 1/16 above the EIU present. When the voltage increases above this value, and follows the synchronization characteristics set above, all the devices know that a link needs to be made, and make one for themselves on the second increase in voltage. Next, there is the Parallel Direction Detection (SM) (PSD) state machine, which performs a variety of jobs. It is responsible for determining if there is any extension in use (EIU) and for generating the appropriate EIU cases of disconnection. It also has the ability to generate connection impulses even when the extensions are in use (if the extensions have the capacity). It does this by synchronizing the links with the extensions in use, and by linking at the same time that they generate a connection impulse. This state machine is called every 20ms in the interruption time after the 4ms interruption. This state machine contains two state devices that do not interact with each other. Only one of the state devices is active at one time, depending on whether the device is in a standby or off-hook state. The code that issues control to the correct state, determines if the correct states are active, and if it does not activate the other device. The distribution code also maintains a counter used by the various states. Referring to Figure 8, the resting PSD is extremely simple and is handled by 5 states. There is a simple threshold value (30V for a 48V battery, 15V for a 24V battery, both in the EEPROM), in which the line voltage is continuously compared. If the line voltage is below this threshold, an extension is presumed to be in use. The Telephone Verification Cord is also found in this SM. When there is EIU, if the voltage falls extremely low, below 2 or 3 volts, the EIU is switched to the Telephone Verification Cord. The states work as follows: Status 0 becomes active each time the device is off-hook. It simply determines whether an extension is in use or not and passes control to state 1 or 2 of the current state. This state also establishes the current trajectory through the attachment for inactive inactivity. State 1 remains active until the line voltage falls below the threshold, in which case the control passes to state 3. State 2 remains active until the line voltage rises above the threshold, in which case the control to state 4. State 3 simply ensures that the line voltage remains below the threshold for a certain period of time and then generates a case of EIU and passes control to state 2, otherwise it returns to state 1. The amount of time that the line voltage is not returned is controlled by a byte in the EEPROM. State 4 simply ensures that the line voltage remains above the threshold for a certain period of time and then generates a case of NEIU and passes control to state 1, otherwise it returns to state 2. The amount of time that the voltage line is not returned, it is controlled by a byte in the EEPROM. Referring to figure 9, the off-hook PSD is much more difficult. The extensions should be detected by observing relatively small voltage drops in the line voltage. For additional complicated things, remote links must be detected in this state. The remote links are basically the disappearance of EIU for a short period of time. The PSD SM off-hook also performs links, both simple and multiple links trying to give extensions the opportunity to link. The status works as follows: Status 5 becomes the current status each time the device is idle. Delay the additional PSD activity by lOOms to give the VCO time to stabilize. When using all the available information, it takes its best guess whether an extension is in use or not and passes the control to either state 6 or 7. It also establishes the current trajectory for the attachment for the inactivation of off-hook. State 6 is active when there are no extensions in use. If it detects a sufficient voltage drop, it passes control to state 8. Status 7 is active when one or more extensions are in use. If it detects the voltage increase above the unregistered EIU threshold, it passes the control to the active state 9. If it detects a slight increase in voltage that could be a remote device making a link (this could happen if there was more than one EIU), it makes the state 12 active. The state 8 simply ensures that the line voltage remains low for a period of time before generating a case of EIU and then makes the state 7 active. If the line voltage does not stay low for long enough, the control returns to state 6. The non-regression time is in the EEPROM. State 9 simply ensures that the line voltage remains elevated for a period of time. If it does not remain elevated it makes the state 6 active and generates a case of NEIU. If it falls below it returns to state 7, unless it falls within a window of the link time case, in which the control passes to state 10. The regression time, and the window link time are all in the EEPROM. State 10 waits for another link after one has been detected. It is delayed after a period of time (controlled in the EEPROM) and jumps to the input state 5. If a link is detected, the control is passed to state 11, where a link is made. The state 11 performs a synchronized link, and then jumps to the input state 5. The duration of the link is found in the EEPROM. State 12 regulates the duration of the light voltage increase. This could be caused when there is more than one EIU, and one of them makes a link. The state regulates the voltage increase, and if it falls inside the link window, it passes the control to state 10, otherwise it jumps to the input state 5. Status 13 becomes active when this device is about to make a link. The state determines your one or more links should be made (depending on the condition of EIU, and if higher links are allowed). If only one link is necessary, the control slides to state 11, otherwise the state performs a link and then passes control to state 14. State 14 controls the amount of time between two links. This then passes the control to state 11.

Claims (14)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. A method for recognizing a customer alert signal sent by a telephone switch through a telephone cycle when the telephone cycle is in the condition, in which at least one telephone set of a plurality of telephone sets is off-hook , the telephone cycle containing the plurality of telephone sets at one end and the telephone switch at the other end, comprises the steps of: assigning a first telephone set to transit to a off-hook state as a master among the plurality of telephone sets and the remaining devices as subordinates during a telephone call; and detecting the alert signal of the client in the master, and responding appropriately to the alert signal of the client depending on the status of one or more remaining telephone sets to indicate that the plurality of telephone sets are ready to receive off-hook signals from the switch telephone. The method according to claim 1, characterized in that it further comprises the steps of: assigning one of the remaining telephone sets as a backup master when the master has been at rest during said telephone call; and detect the alert signal of the client in the reservation master and respond appropriately to the customer's alert signal. The method according to claim 1, characterized in that it comprises an additional step of decreasing the intensity of the speech path for a predetermined period of time in all telephone apparatuses after the detection of the alert signal of the client. The method according to claim 3, characterized in that the step of responding comprises a step of sending a recognition signal from the master to the switch. The method according to claim 4, characterized in that it comprises a further step of receiving an FSK signal from the switch after the acknowledgment signal. The method according to claim 5, characterized in that it comprises an additional step of removing the FSK signal from any of the telephone devices. The method according to claim 1, characterized in that it comprises an additional step of removing a circuit with DC termination in all telephone sets for a predetermined period of time after reception of the customer alert signal. The method according to claim 7, characterized in that it comprises an additional step of reapplying the DC termination circuit in all telephones. 9. A telephone set to be connected to a telephone cycle characterized in that it comprises: a circuit for monitoring the DC condition of the telephone cycle, to determine if one or more telephone sets are in off-hook state between a plurality of telephone sets, which are connected to the telephone cycle; a demodulation circuit for detecting a customer alert signal sent by the switch connected to the telephone cycle when the telephone cycle is in a hook-off condition; a line operation circuit for sending a recognition signal in response to the customer alert signal; and a controller for assigning a telephone device as a master if it is the first telephone device to transit to the off-hook state between the plurality of telephone sets and to allow the line operation circuit when a customer alert signal is detected. 10. The telephone apparatus according to claim 9, characterized in that it further comprises a DC termination circuit, which can be inserted into and removed from the telephone cycle in response to the command from the controller. 11. The telephone set according to claim 10, characterized in that it also comprises a circuit for decreasing the intensity of the speech path, which can be inserted into and removed from the telephone cycle in response to an order from the controller. 12. A telephone station apparatus, of a type that includes display means for displaying information in response to coded signals received from a telephone switching facility, characterized in that it comprises: a network including a direct current path and a voice band signal path; a line status detector to detect the status of the telephone line according to whether it is in a resting position and is unlocked; means responsive to an event of a first predetermined signal from the telephone switching facility, and subsequently within a fixed time interval in an event of a second predetermined signal to decrease the path intensity of the voice band signals during a predetermined period of time, during the state of DISCHARGED; means that respond to a signal coming from the line status detector to register either condition, (a) if the telephone station apparatus was the first to transit to the DISCOLVED state, or (b) if the device the telephone station was the subsequent one to transit to the DISCHARGED state, during any interval, when at least one device of the telephone station connected to the telephone line is DISCOLVED; means for causing a recognition signal to be transmitted to the telephone switching facility while decreasing the intensity of the receiving and transmitting paths, conditional of the means for registering, having the condition (a) registered in the apparatus of the telephone station; by means of which the telephone switching facility is enabled to transmit the coded signals. The telephone apparatus to be connected to a telephone cycle according to claim 9, characterized in that it further comprises: the controller to assign one of the remaining telephone sets as a backup master, if the master is at rest and to enable the circuit of line operation if the telephone set is assigned as reservation master. 14. The apparatus of the telephone station according to claim 12, characterized in that the information that is displayed refers to a part of the call.