JPH0783409B2 - Interrupt call method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an interrupt call system for digital exchanges such as EPBXs and button telephones.

(Prior Art and Its Problems) Conventionally, an interrupt call in a digital exchange device has been performed in a conference call format. An example of the conference call system is shown in FIG. Here, LN is an office line or a dedicated line, TEL ₁ and TEL ₂ are extension telephones, H ₁ and H ₂ are hybrid circuits, A ₁ , A ₂ , A ₃ , A ₄ , A ₅ and A ₆ are buffer amplifiers, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ are resistors,
MX is a mixing circuit. Fig. 1 shows an example of a conference call between a station line and two telephones. It is possible to communicate between the station line and telephones and between telephones by passing through the mixing circuit MX of the same configuration without distinction between the station line and telephones. I am trying.
When there is a two-wire / four-wire conversion circuit in the conference call interrupt call system, a call loss must be given to the mixing circuit in order to prevent howling and ensure the intelligibility of the call. . Therefore, there is a drawback that a call loss is evenly given to a call between a station line and a telephone set, and between telephone sets, and it is difficult for the extension line telephone to hear the voice from the station line depending on the line condition of the station line. In FIG. 1, in order to eliminate the above-mentioned drawback, the mixing connected to the office line may be constructed lossless, but in that case, the circuit becomes complicated.

(Object of the Invention) The present invention provides an interrupt call system capable of transmitting a voice from a telephone line to a telephone to an extension telephone without any loss during an interrupt call.

(Characteristics of the invention) In a digital switching device such as EPBX, during a mutual call between a local line or a dedicated line for analog signal transmission (hereinafter referred to as a "station line") and an extension telephone (hereinafter referred to as a telephone) connected to the switching device, In an interrupt call system in which a plurality of telephones other than the above telephones interrupt the call line, the voice from the office line to the plurality of telephones is configured to be distributed to each of the telephones without any loss. Voice from each telephone is added by adding the voice from each telephone and adding a loss to the addition circuit to the extent that the balance of the 2-wire / 4-wire conversion circuit (hereinafter referred to as hybrid circuit) of the station line is not impaired. In addition to sending out the voice to the office line, the balance constant is set in advance so that the wraparound attenuation of the hybrid circuit of the station line is reduced to about 10 dB in advance so that the extension call between the telephones by the wraparound can be performed. A call waiting mode, characterized in that form.

(Embodiment) FIG. 2 is an embodiment of the present invention in which two telephones are used for one station line or one dedicated line. In the embodiment of FIG. 2,
The office line or the dedicated line LN is applied to the receiving side buffer amplifier A ₁₁ in the mixing circuit MX-A via the hybrid circuit H ₁ , and the output thereof is further applied to the buffer amplifiers A ₁₂ and A ₁₃ . The output of the buffer amplifier A ₁₂ is directly transmitted to the extension telephone TEL ₁ via the hybrid circuit H ₂ . The output of the extension telephone TEL ₁ is applied to the adder A ₁₄ via the hybrid circuit H ₂ and the resistor R ₁₁ , and the output of the extension telephone TEL ₂ applied via the resistor R ₁₂ is superimposed and added in the adder A ₁₄ . The added output is sent to the local line or the dedicated line LN via the hybrid circuit H ₁ .

In Fig. 2, the voice from the office line LN is lossless and each telephone
TEL1, transmitted to the TEL _2. Further, the voices coming from the respective telephones TEL ₁ and TEL ₂ to the office line are added by the adder A ₁₄ and sent to the office line LN. At this time, since the hybrid circuit H ₁ on the local line side exists, the gain of the adding circuit A ₁₄ is adjusted to one side (−6 dB in FIG. 2) to prevent howling, and the loss is caused to the extent that there is no hindrance to the call. give.

In this way, by giving a loss to the voice from the extension telephones TEL ₁ and TEL ₂ to the station line LN, the housing during the call between the station line LN and the extension telephones TEL ₁ and TEL ₂ is prevented and the hybrid circuit H ₁ The wraparound attenuation of the hybrid circuit H ₁ should be used between the extension telephones TEL ₁ and TEL ₂ by setting the wraparound attenuation of 5 to 15 dB (10 dB as a preferable example). At (TEL ₁ → H ₂ →
R ₁₁ → A ₁₄ → H ₁ → A ₁₁ → A ₁₃ → TEL ₂ ] and [TEL ₂ → R ₁₂ → A ₁₄ →
The route of H ₁ → A ₁₁ → A ₁₂ → H ₂ → TEL ₁ ] enables a call without howling.

FIG. 3 is a block diagram showing a connection system when two-line type and four-line type extension telephones are respectively housed in a composite base.

Since its operation is the same as that of FIG. 1, a detailed description thereof will be omitted, but according to the method of the present invention, even if about 10 extension telephones are simultaneously connected and a conference call is made, there is no sufficient howling. It is implemented that the call is possible. Normally, when conducting a conference call, at present, about three-way simultaneous call is general, and the conference call system of the present invention capable of ten-way simultaneous call can sufficiently provide its function.

(Effects of the Invention) As described above, the present invention has no loss in voice from a central office line, and thus is advantageous in an interrupt call for monitoring during a call, particularly when it is desired to know information from the central office side. is there. Further, there is an advantage that the circuit configuration is simple and mutual communication is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a conventional conference call system,
2 and 3 show an embodiment of the present invention. LN ...... office line or dedicated _{line, H 1, H 2, H} 2n ...... hybrid _{circuit, A 11, A 12, A} 13, A 21, A 2n, A 31, A 3n ...... buffer amplifier, A _14, A ₄₁ ...... Adder, TEL ₁ , TEL ₂ ,, TEL _1n , TEL _2n ...... Extension telephone, R _{1 to} R ₉ ,, R ₁₁ , R ₁₂ , R ₂₁ ,, R _2n ...... Resistance, MX, MX-
A: Mixing circuit.

Claims (1)

[Claims] 1. A four-line transmitting side of a hybrid circuit in which the two-line side is connected to one office line or one dedicated line does not give a specific loss, and a plurality of extension telephones of the extension telephones are respectively provided through corresponding buffer amplifiers. The four-line receiving side is connected to the four-line receiving side, the four-line transmitting sides of the plurality of extension telephones respectively give corresponding losses, and the addition outputs added by a single adder are connected to the four-line receiving side of the hybrid circuit, By setting the balance constant of the hybrid circuit so that the wraparound attenuation amount of the hybrid circuit becomes a predetermined low value of about 10 db, the wraparound attenuation amount is used to interrupt between the plurality of extension telephones. An interrupt call system that is configured to allow calls.