JPH01245656A - Privacy telephone trunk line connection system - Google Patents

Abstract

PURPOSE:To connect a trunk line for privacy call without providing a privacy telephone set on the trunk digital data exchange-side by providing a privacy call trunk line only to a subscriber's line digital data exchange and connecting crosswise this trunk line to a channel switch. CONSTITUTION:In the subscriber's line digital data exchange LS 3, if a callee subscriber SUB 7 answers, a central control unit CC 35 detects this through a subscriber's circuit LC 31, and controls the channel switch SW 32 to disconnect the link between the LC 31 and a trunk line (TRK) 33. Then a LC 31- privacy call trunk (PFT) 34-TRK 33 channel is set, and controls to return a callee response signal which is received by a TRK 13. In an exchange LS 1, a central control unit CC 15 detects this callee response signal through a TRK 13, and controls a switch SW 12 to disconnect the link between the TRK 13 and the LC 11, so that a TRK 13-PFT 34-LC 11 channel is set. As a result, between a SUB 4 and SUB 7, a privacy channel through the PFTs 14, 34 is set.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a secret trunk line connection system, and more particularly to a secret trunk line connection system for privately communicating calls connected to a trunk line in a digital telephone switching network.

[Conventional technology]

Conventionally, this type of secret trunk line connection system has provided secret devices on a one-to-one basis in all the trunks of subscriber line digital exchanges and trunk line digital exchanges constituting a digital telephone switching network.

[Problem to be solved by the invention]

In the conventional secret trunk line connection method described above, when constructing a large telephone switching network with many exchanges or when there are many trunk lines, the conventional secret trunk line connection method is to install confidential telephone equipment at both ends of the trunk line, that is, twice the number of trunk lines. This has the disadvantage that it is a very expensive system.

[Means to solve the problem]

In the confidential trunk line connection system of the present invention, subscriber line digital exchanges installed at both end stations of a digital telephone exchange network are equipped with confidential trunks that accommodate both incoming and outgoing terminals in the communication path switch, and the subscriber line digital exchange on the receiving side is equipped with a confidential trunk that accommodates both input and output terminals. When the called party answers, the call path between the subscriber circuit, the secret trunk, and the trunk trunk is set through the call route switch of the called party, and the calling party's personal line digital exchange connects the subscriber's line digital exchange with the called party's subscriber line digital exchange. The system is characterized in that upon reception of a called party response signal from the station, a communication path between a trunk trunk, a secret trunk, and a subscriber circuit is established via a communication path switch of the own station.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the secret trunk line connection system of the present invention.

In FIG. 1, the digital telephone switching network consists of a subscriber line digital switch (hereinafter referred to as LS) 1 accommodating subscribers (hereinafter referred to as 5UB) 4, an LSI and a digital transmission line (hereinafter referred to as LN) 5.
Trunk line digital switching equipment (hereinafter referred to as TS) connected via
)2 and LS3 connected via TS2 and LN6, and LS3 accommodates 5UB7. LSI
is the subscriber circuit (hereinafter referred to as LC) 11, the communication path switch (hereinafter referred to as 5W) 12, the trunk trunk (hereinafter referred to as TRK) 13, the private trunk (hereinafter referred to as PFT) 14, and the central control unit that controls all the sequences within the LSI. control device (hereinafter referred to as CC),
15, LCII is housed in 5W12 and has 5UB
4 and TRK13 are accommodated in 5W12 and L N ,
5, and both input and output terminals of PFT14 are ζW.
12, so-called stingy connection is made. Also LS3
is LC31, 5W32. as well as LSI. TRK33. ,
Equipped with PFT34 and CC35, LC31 is 5UB7,
TRK33 also interfaces with LN6.

Furthermore, TS2 interfaces with LN5
3, T, R, and 21 that interface with ILN6, and 5W22 that accommodates TRK21.23. Note that the PFTs 14 and 34 are trunks that convert a digital signal input from one terminal according to certain rules and output the converted signal to the other terminal, and both have the same rules.

Next, the operation of this embodiment will be explained using an example in which 5UB4 makes a call and performs a confidential trunk line connection conversation with 5UB7.

After 5UB4 goes off-hook and confirms the dial tone, dials 5UB7's phone number, 5UB4-LCI 1-8
W12 (solid line diagram)-TRK13-LN5-TRK2
3-8W22-TRK21-LN6-TRK33-8W
32 (shown with solid line) -LC34-SUB7 communication path is set. These connections are well known and are
, 3, and a central control unit (not shown) of TS2, so a description thereof will be omitted.

In LS3, when the called 5UB7 responds, CC'
35 detects this via LC31, controls 5W32, disconnects the link between LC31 and 'I'RK33, and connects LC31-P F T 34-TRK3 as shown by the broken line.
3 is set, and a called party response signal is sent back. This called party response signal is LN6. TS2', LN
5 and is received by TRK13. CC in LSL
l3 detects this called party response signal via TRK13,
5W12 and TRK13. Cut the link between LC11 and connect TRK13-P'FT34- as shown by the broken line.
Set the call path for LC11. Therefore 5UB4 and 5U
There is a PFT14 between it and B7. :34 is established.

〔Effect of the invention〕

As explained above, the present invention provides a confidential communication trunk only in the subscriber line digital exchange and connects it to the call route switch of the own station, thereby eliminating the need to install a confidential communication device on the trunk line digital exchange side. Since confidential trunk line connections can be made, an extremely economical digital telephone switching network can be constructed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the secret trunk line connection system of the present invention. 1.3... Subscriber line digital switch (LS), 2.
...Trunk line digital switch (TS), 4,7. ...Subscriber (SUB), 5.6...Digital transmission line (LN)
), 11.31... Subscriber circuit (LC), 12.22
．． 32...Communication path switch (SW), =6-1B, 21,23.33...Relay line l rank (TR
1(), 14.34... Confidential Trunk (PFT), 1
5.35...Central control unit (CC).

Claims (1)

[Claims] The subscriber line digital exchange installed at both end stations of a digital telephone switching network has a confidential trunk that accommodates both incoming and outgoing terminals in the call path switch. A communication path between the subscriber circuit, the private trunk, and the trunk trunk is set via the communication path switch, and the originating subscriber line digital exchange receives the called party response signal from the terminating subscriber line digital exchange, and then the call path is established. A confidential trunk line connection method characterized by setting a communication path between a trunk trunk, a private trunk, and a subscriber circuit through a communication path switch.