JPH01189272A - System for switching lines - Google Patents

Abstract

PURPOSE:To automatically execute a changeover mutually by sending dial signals mutually, detecting a calling sound from a public line, operating a changeover switch, and simultaneously, sending the dial signal to an opponent side. CONSTITUTION:Communicating devices 2 and 3 to be opposite are connected through line changeover switches 4 and 5 to a private line 1 and public lines 17 and 18. When the communicating device 2 detects that the carrier of the private line 1 is interrupted, a dial transmitting means 8 is activated by a carrier interruption detecting signal 12. The dial transmitting means 8 sends a dial signal 14 to an exchange 16. When the exchange 16 calls the opponent side, a calling signal detecting means 7 transmits a calling sound detecting signal 11 to a dial sending means 9, a dial signal 15 is sent to the public line, and simultaneously, the changeover switch 5 is switched to a public line side. In the same way, a calling signal detecting means 6 detects the calling sound from the public line 17, and the changeover switch 4 is switched to the public line side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to communication line backup, and particularly to a method for backing up a dedicated line using a public line.

[Conventional technology]

Conventionally, as this type of backup method, a method has been widely used in which a call is automatically made and switched to a public line when the dedicated line is disconnected.

[Problem that the invention seeks to solve]

This conventional system has the disadvantage that it cannot be used for high-speed, full-duplex communication because the public line is a two-wire system. Therefore, when performing high-speed full-duplex communication, use two public lines.
However, in this case, the switching must be done mutually between the opposing communication devices, and if the method simply detects carrier disconnection of the dedicated line and switches, it would be difficult to switch between sending and receiving of the dedicated line. If one or both lines were disconnected, there was a problem in that mutual switching could not be performed. Additionally, since it uses a public telephone line, there is a drawback that it cannot be backed up in the event that an erroneous call is received from a third party.

[Means for solving problems]

The line switching system of the present invention includes means for detecting a carrier of a dedicated line, means for detecting a ring tone from a public line, means for dialing to the public line, and means for detecting a specific code. Consists of opposing communication devices.

〔Example〕

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

FIG. 1 is a block diagram of one embodiment of the present invention.

The opposing communication devices 2 and 3 are connected to the dedicated line 1 and public lines 17 and 18 via line changeover switches 4 and 5. The ringing signal detection means G and 7 detect the ringing tone from the public line 16. The dialing means 8 and 9 are
The dial signal 14 or 15 is connected to a public line 17 or 18.

When the communication device 2 detects that the carrier of the dedicated line 1 is disconnected, the dial transmitting means 8 is activated by the carrier disconnection detection signal 12.

The dialing means 8 sends a dialing signal 14 to the exchange 16. When the exchange 16 calls the other party, the ringing signal detection means 7 transmits the ringing detection signal 11 to the dialing means 9, and transmits the dialing signal 15 to the public line,
Switch the changeover switch 5 to the public line side. Similarly,
The ringing signal detecting means 6 detects the ringing tone from the public line 17 and switches the changeover switch 4 to the public line side.

〔Effect of the invention〕

As explained above, the present invention transmits dial signals to each other, detects the ringing tone from the public line, operates the changeover switch, and transmits the dial signal to the other party, thereby automatically switching between the two parties. It will be held in

A code sending means is added to the dialing signal sending means of the present invention, a code detecting means is added to the calling signal detecting means, and when the corresponding code is not detected, sending a dialing signal to the other party and switching the changeover switch are prohibited. By configuring the system to do so, it is possible to prevent interference due to erroneous incoming calls from third parties.

Further, since the carrier detecting means, paging signal detecting means and dialing signal transmitting means of the present invention can utilize the functions of a commonly used network control device as they are, the present invention can be constructed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention. 1... Dedicated line, 2, 3... Communication device, 4, 5... Line changeover switch, 6, 7...
. . . Ringing signal detection means, 8, 9 . . . Dial signal sending means, 10° 11 . . . Ringing tone detection signal, 12. 13 . 15
...Dial signal, 16 ... Switchboard,
17.18...Public line. Agent: Patent Attorney Otowa Uchihara

Claims (1)

[Claims] means for detecting that the carrier of the leased line is interrupted;
In an opposing communication device comprising means for detecting a ringing tone from a public line, means for dialing to the public line, and means for detecting a specific code, when the carrier of the dedicated line is interrupted, A line switching method characterized by automatically calling a public line.