JPS63252056A - Private branch exchange system - Google Patents

Abstract

PURPOSE:To attain bypass connection even if a public network line connected directly to a private branch of exchange is faulty by connecting private branch of exchanges by a private line and relaying a call from a private branch of exchange via the private line. CONSTITUTION:In applying the exchange connection connecting a telephone terminal set 3 to a telephone terminal set 4 in a public network under the control of a private branch of exchange 1, the private branch of exchange 1 applies relaying to a call from the telephone terminal set 3 via a private line 2 and the private branch of exchange 1'' to apply succeeding connection to the exchange 5'' connecting directly to the private branch of exchange 1'' to make a call to a telephone terminal set 4. As a result, even if a transmission line between the private branch of exchange 1 and the exchange of the public network is faulty, the telephone terminal sets 3, 4 are connected and the private branch of exchange network is utilized as much as possible effectively without using the public telephone network to the utmost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a private telephone switching system, and particularly to a local telephone exchange in a plurality of private telephone exchange networks connected by dedicated lines.

(Prior Art) When making a telephone exchange connection from a certain telephone terminal to a telephone terminal within the public network, if the conventional private branch exchange learns that the call is to be terminated at a telephone terminal within the public network, The subsequent exchange connection operation is then entrusted to the public network exchange that is directly connected to the private telephone exchange.

(Problems to be Solved by the Invention) In the conventional private branch telephone switching system, all calls received from telephone terminals belonging to a private branch telephone exchange to telephone terminals in the public network are sent to public telephone terminals directly connected to the private branch telephone exchange. Since switching connection operations are entrusted to network exchanges, (a) if a failure occurs in the transmission line between a certain private branch telephone exchange and a directly connected exchange in the public network, that private branch telephone exchange It is no longer possible to make calls within the public network from telephone terminals under the Even in the case of a public telephone network, the connection is made through the public network, which has the disadvantage that the private branch exchange network cannot be used effectively.

(Means for Solving the Problems) A private branch telephone exchange according to the present invention is capable of connecting a private branch telephone exchange to a telephone terminal in a public network when making a telephone exchange connection for an incoming call from a telephone terminal under a certain private branch telephone exchange to a telephone terminal in a public network. This system is equipped with a function that enables an exchange connection to be made via a private telephone exchange within a private telephone terminal, which is different from the private telephone exchange under which the calling telephone terminal is subordinated.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

Figure 2 is a block diagram of a conventional telephone switching system.
Private branch exchange 1.1', 1'' is dedicated line 2.2', 2'
are linked together to form a private telephone exchange network. When a telephone terminal 3 under a private telephone exchange 1 performs an exchange connection to receive a call to a telephone terminal 4 in a public network, according to this conventional example, the private telephone exchange 1 is directly connected to the private telephone exchange 1. As a result, the exchange 5 entrusts the subsequent exchange connection operation to the exchange 5 in the public network located in the public network.
......, pass through 5'.

FIG. 1 is a block diagram of an embodiment of the invention.

According to the present invention, the private branch telephone exchange 1 relays a call from the telephone terminal 3 via the dedicated line 2 and the private branch telephone exchange 1' to an exchange in the public network that is directly connected to the private branch telephone exchange 1'. 5' performs the subsequent connection operation and the telephone terminal 4 receives the call. As a result, the private telephone exchanges 1 to 1 shown in FIG.
Even if the transmission line between the exchanges 5 of the public network is out of order,
It is possible to connect between the telephone terminals 3 and 4, and it is also possible to effectively utilize the private switched telephone network without using the public network as much as possible.

(Effects of the Invention) As explained above, according to the present invention, when the transmission line between the private branch exchange and the directly connected public network exchange is out of order (even if the transmission line between the private branch exchange and the directly connected public network exchange is This will be of great help in improving the functionality of private branch exchanges, as it will enable economical benefits by effectively utilizing leased lines and reducing the use of public networks as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a private telephone switching system according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional telephone switching system. 1.1', 1''...private telephone exchange, 2.2', 2
'... Dedicated line connecting the private telephone exchange, 3... Terminal under the private branch telephone exchange, 4... Telephone terminal in the public network, 5.5', 5'... Exchange in the public network. Agent Patent Attorney Toshiyoshi Somekawa Figure 1

Claims (1)

[Claims] When making a telephone exchange connection for incoming calls from a telephone terminal under a certain private branch telephone exchange to a telephone terminal in the public network in multiple private branch switched networks connected by private branch telephone exchanges, it is necessary to A private telephone switching system characterized in that an exchange connection is established by relaying a telephone call through a private telephone exchange different from the private telephone exchange under which a calling telephone terminal is subordinated.