JPH05219550A - Method of holding telephone call during power failure at exchange - Google Patents

Abstract

PURPOSE:To hold the telephone call even though an abnormality occurs in the power supply during the call by setting a direct circuit between a telephone set for power failure and an exchange subscriber line when detecting the voltage deterioration of the local power supply during the call. CONSTITUTION:A power supply abnormality detection circuit 16 monitors the voltage of a local power supply 3 at all times. When the input voltage is lower than the reference voltage generated by a constant voltage generation circuit, an interruption is generated for a CPU 17. The CPU 17 recognizes the abnormality of the input power supply by means of the interruption and controls a call changeover circuit during power failure to set a circuit directly connecting a telephone set 5 for power failure and an exchange subscriber line 2. In this case, the circuit 11 will not start for an exchange subscriber during the call. Thus, the effective telephone call for subsequent originating and incoming calls can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power failure countermeasure telephone connected to a station subscriber line including an ISDN line through a call switching circuit at the time of power failure, or an extension telephone including a telephone directly connectable to the station subscriber line. The present invention relates to a call holding method during a power failure in a telephone exchange device which has a switching function and operates by a local power supply.

[0002]

2. Description of the Related Art In a private branch exchange (PBX) and a key telephone device, a call switching circuit (PFT circuit) during a power failure and a telephone for power failure are generally adopted as a method for holding a telephone call to a subscriber line during a power failure. There is.

A conventional system using a PFT circuit is shown in FIG.

That is, a station subscriber line 21 and a station subscriber circuit (not shown) are provided so as to be connectable via a relay R1, and an extension circuit (not shown) and an extension telephone (this telephone is
22 which has a circuit capable of being directly connected to the station subscriber line) is provided so as to be connectable via a relay R3, and the station subscriber line 21 and an extension telephone set 22 are provided so as to be directly connected via a relay R2. Has been. And normally, the relays R1 and R3
Is ON, relay R2 is OFF, and power is cut off, relay R
1, R3 is turned off and relay R2 is turned on. The ON / OFF switching of each of the relays R1, R2 and R3 can be performed by control from a CPU (not shown).

That is, the switching device that has detected a power failure electrically connects the station subscriber line 21 and the extension telephone 22 directly by the relay R2, so that the extension telephone 22 is limited to a specific extension telephone 22 and is connected to the station subscriber line. It is designed to secure outgoing calls, incoming calls and communications.

[0006]

In the above method, when a power failure occurs, a call can be effectively secured after a direct connection circuit is set up between a specific extension telephone 22 and a station subscriber line 21. .. However, when a call was in progress when the power failure occurred, the direct current circuit of the extension telephone set with the direct connection circuit was opened, or the extension telephone set with the direct connection circuit was IS.
In the case of the DN telephone, the call is interrupted, and there is a problem that the call cannot be set again unless one of the calls is made again.

The present invention has been made in view of the above circumstances, and an object thereof is to activate a transfer function during a call which is one of ISDN network functions and set a direct connection circuit when a power failure is detected. It is an object of the present invention to provide a method of holding a call during a power failure of a telephone exchange that transfers a call in progress to a telephone and prevents the call from being disconnected during the call.

[0008]

In order to solve the above-mentioned problems, a method of maintaining a telephone call during a power failure of a telephone exchange apparatus according to the present invention is connected to a station subscriber line including an ISDN line via a telephone call switching circuit during a power failure. In a telephone exchange that has a function of exchanging with a power outage countermeasure telephone or an extension telephone including a telephone that can be directly connected to a station subscriber line and that operates by a local power source, during a call by any extension telephone by the ISDN line. When a voltage drop of the local power source is detected, a direct connection circuit is set between the telephone for power failure countermeasure or a telephone that can be directly connected to a station subscriber line and a station subscriber line via the call switching circuit at the time of power failure, After that, by requesting the ISDN line during the call to activate the call transfer function,
The ISDN line during a call and the power failure countermeasure telephone or the telephone directly connectable to the subscriber line are held in a ringing or busy state.

[0009]

When a voltage drop of the local power supply is detected during a call by any extension telephone by the ISDN line, the telephone exchange device connects the telephone for power failure countermeasure or the telephone directly connectable to the station subscriber line and the station subscriber line. Set up a direct connection circuit via the call switching circuit during a power failure. After that, the telephone exchange device requests the ISDN line in communication to activate the transfer function during communication, which is one of the ISDN network functions. As a result, according to a certain communication procedure, the ISDN line during a call and the power failure countermeasure telephone or the telephone that can be directly connected to the station subscriber line are held in a ringing or busy state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical construction of a telephone exchange device for realizing the method of holding a call during a power failure according to the present invention.

In the figure, the station subscriber line 2 is connected to a station subscriber line circuit 12 including an ISDN line via a PFT circuit 11 of the telephone exchange apparatus 1, and the station subscriber line circuit 12 is , Is connected to the exchange circuit 13. Further, the exchange circuit 13 is connected to the extension circuit 14. A general extension telephone 4 is connected to the extension circuit 14, and a telephone for power failure countermeasure or a telephone that can be directly connected to a station subscriber line (hereinafter, referred to as a telephone for power failure countermeasure) is connected via the PFT circuit 11. ing.

On the other hand, the local power supply 3 is supplied to each circuit through the power supply circuit 15 and is also connected to the power supply abnormality detection circuit 16. The output of the power supply abnormality detection circuit 16 is a power interruption signal. It is guided to the CPU 17 that controls the operation of the entire telephone exchange device 1. And C
The output of the PU 17 is guided to the exchange circuit 13 and the PFT circuit 11.

The CPU 17 controls the exchange circuit 13 and the PFT circuit 11 according to the power failure interrupt processing routine based on the power failure interrupt signal from the power supply abnormality detection circuit 16.
Call transfer processing operation is performed between the switching circuit 13 and the ISDN network.

Although not shown, the power supply abnormality detection circuit 16 is composed of, for example, a constant voltage generating circuit using a regulator, a rectifying / smoothing circuit, and a comparator having an output of each circuit as an input. The output of the constant voltage generation circuit and the input voltage obtained by rectifying and smoothing the local power supply are compared by the comparator, and the CPU 17
It is possible to create a power failure interrupt signal that generates an interrupt for.

Next, the operation of the telephone exchange device having the above configuration will be described.
This will be described with reference to the operation sequence shown in FIG.

The power supply abnormality detection circuit 16 includes a local power supply 3
The voltage of is constantly monitored. When the power supply input voltage is lower than the reference voltage generated by the constant voltage generating circuit, it is determined that there is a power failure, and an interrupt is issued to the CPU 17.

The power supply circuit 15 of the telephone exchange apparatus 1 is generally set to hold for a certain short time even if the voltage of its input power supply drops or is cut off. Therefore, when the CPU 17 recognizes the abnormality of the input power source by the interruption, it controls the PFT circuit 11 to set the direct connection circuit between the power failure countermeasure telephone 5 and the station subscriber line 2. At this time, the PFT circuit 1 is connected to the station subscriber line during the call.
Do not start 1.

As a result, the call can be effectively secured for the subsequent outgoing calls and incoming calls.

On the other hand, when a call is being made by any extension telephone 4 via the ISDN line at the time of power failure, the CP
The U17 sends a call transfer message 41 requesting activation of the call transfer function, which is one of the ISDN network functions, to the ISDN line during the call. The transfer destination is the station subscriber line 2 to which the power failure countermeasure telephone 5 is directly connected. IS
The DN network receives the call transfer message 41 to put the line on hold, and then sends the hold message 42 to the telephone exchange 1. After this, the telephone exchange 1 sends a hold confirmation message 43, the ISDN network sends a status recognition message 44, and the telephone exchange 1 sends a call setup message (transfer destination telephone number) 45. This transfer destination telephone number is a PFT-set office line number, which is set in advance.

The ISDN network sends a call or response message 46 to this transfer destination telephone number, and the call switching device 1 sends a call transfer message 47 to complete the transfer. As a result, the ISDN line during the call and the power failure countermeasure telephone 5 are held in the form of a call or a call. Therefore, the power failure countermeasure telephone 5 can continue the call with the person who is busy through the ISDN line.

As described above, according to the call holding method during a power failure of the telephone exchange apparatus according to the present invention, even if a power failure such as a power failure occurs during a call, the call can be maintained.

Further, for example, in the case of a telephone call for a business telephone, it is often the case that the contact information of the other party is unknown until confirmation is made before ending the call. In such a case, the line is forcibly disconnected due to a power failure or the like. Then, it becomes difficult to recover the call with the same person again. Therefore, the call holding method during a power failure of the present invention, which always secures a call during a call, is extremely useful in a business communication device.

[0024]

According to the method for holding a telephone call during a power failure of the telephone exchange apparatus according to the present invention, when a voltage drop of the local power supply is detected during a call by any extension telephone by the ISDN line, the telephone for the power failure countermeasure and the station subscriber. A direct connection circuit is set between the line and the ISDN line during a call to request the activation of the call transfer function during the call.
Since the N line and the power failure countermeasure telephone etc. are configured to be held during a call or during a call, even if a power failure occurs due to a power failure during a call, it will continue to hold the call at that time. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a telephone exchange device for realizing a call holding method during a power failure of the present invention.

FIG. 2 is an explanatory diagram showing a communication procedure for carrying out the method of holding a call during a power failure according to the present invention.

FIG. 3 is a diagram showing a PFT circuit.

[Explanation of symbols]

1 Telephone switching device 2 Station subscriber line 3 Local power supply 4 Extension telephone 5 Telephone for power failure countermeasure or telephone that can be directly connected to station subscriber line 11 Call switching circuit (PFT circuit) at power failure 16 Power supply abnormality detection circuit 17 CPU

Claims (1)

[Claims] 1. A function of exchanging with a station subscriber line including an ISDN line and an extension telephone including a telephone for power failure countermeasure connected via a call switching circuit at the time of power failure or a telephone directly connectable to the station subscriber line. In a telephone exchange apparatus that operates by a local power source, when a voltage drop of the local power source is detected during a call by any extension telephone by the ISDN line, a telephone that can be directly connected to the power failure countermeasure telephone or a station subscriber line A direct connection circuit is set between the call and the subscriber line through the call switching circuit at the time of power failure, and thereafter, the activation of the call forwarding function is requested to the ISDN line during the call, whereby the ISDN during the call is requested. A call holding method during a power failure of a telephone exchange, characterized in that a line and the above-mentioned power failure countermeasure telephone or a telephone that can be directly connected to a local subscriber line are held in a calling or talking state.