JPS584880B2 - Subscriber line multiplexing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a subscriber line multiplexing system that multiplexes between an exchange and a terminal.

In the conventional space-division switching system, a subscriber line is assigned to each subscriber, and the accommodation terminal (MDF) for that subscriber line is provided at the switching center, so the space for the accommodation terminal, etc. Due to physical limitations, it was not possible to downsize the switching center.

Furthermore, since the subscriber line and the terminal are connected one-to-one, there is a drawback that the usage efficiency of the subscriber line is low.

In addition, the time-division switching system proposed by the U.S., for example, installs a line concentrator at a remote terminal station and multiplexes digital lines between the line concentrator and the main station, thereby making subscriber lines more economical. However, since the line concentrator uses a space division switching system, the subscriber line and terminal are one-to-one, as mentioned above.
The disadvantage was that the usage efficiency of the subscriber line was low.

The present invention improves the above-mentioned drawbacks, and its purpose is to improve the efficiency of subscriber line usage, and to facilitate expansion of the number of accommodated terminals by eliminating the subscriber receiving terminal (MDF) at the switching center. The goal is to

To achieve this objective, the present invention eliminates the provision of terminals for subscribers in the switching center, ie, subscriber receiving terminals (MDF), and multiplexes subscriber lines.

Examples will be described in detail below.

FIG. 1 is a block diagram of essential parts of an embodiment of the present invention.
1 is an exchange, 11 is a channel device, 12 is a signaling device, and 13 is a control device.

2 is a multiplexed subscriber line; 21 is a telephone line;
22 is a clock line, 23 is a signal line, and 24 is an address line.

Further, 3 is a terminal, 31 is an interface device, 32
is a telephone.

The communication line 21 is connected to the communication path device 11 and used synchronously according to the clock on the clock line 22, and communication between the exchange 1 and the terminal 3 is carried out asynchronously using the signal line 23 and the address line.

The control device 13 also stores whether the terminal 3 is empty or occupied, and sends an address signal to the address line 24 and a request signal to the signal line 23 in a predetermined order.

The interface device 31 identifies the received address signal and operates only when it is the own terminal number, and sends a signal indicating the current state of the telephone 32, that is, whether it is on-hook or off-hook, to the signal device 12 of the exchange 1 via the signal line 23. Send to.

The control device 13 analyzes the signal received by the signaling device 12 and identifies whether the telephone 32 is capable of requesting a call or receiving a call;
Specify the empty channel number and send it to the signal line 23.

By receiving the empty channel number at the interface device 31, a channel between the terminal 3 and the switching center 1 is established, and switching operations and communication operations are performed via the communication line 21 and the communication path device 11.

That is, dial information is sent to the exchange through the established channel during a call operation.

In order to perform the above operations, the interface device 31 connects the telephone 32 to the address decoder and the telephone line.
It is equipped with a gate for connecting and disconnecting, a function for transmitting signals to the signal line 23, a function for storing and transmitting numerical information from the telephone set 32, and an A/D and D/A conversion function for connecting and disconnecting with the telephone line 21. .

As mentioned above, since the switching center 1 is not provided with a subscriber receiving terminal (MDF), the space of the switching center 1 can be saved and the size can be reduced. Since it is not affected by the capacity of , it can be easily dealt with.

FIG. 2 is a block diagram of main parts of another embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same parts, 231 is a request line, and 232 is an accept line.

In this embodiment, the terminal 3 is connected to the switching center in a similar manner, and when a call is made, a request signal is sent from the interface device 31 via the request line 231, and this request signal is received by the signaling device 12 of the switching center. Then, the control device identifies it and sends an accept signal through the accept line 232.

Since this accept line 232 is connected to each terminal 3 in an interlocking manner, even if there are simultaneous calls, the calling terminal closest to the exchange receives the accept signal and transmits the accept signal to the subsequent accept lines 232. By preventing the communication from being sent, priority is given to the terminal closest to the exchange and the call is made.

In each of the embodiments described above, the subscriber line 2 includes the telephone line 21,
This figure shows a case where the clock line 22, signal line 23, and address line 24 are used, but if these are combined using one high-capacity optical fiber, for example, and used in a time-sharing manner, more subscriber lines can be connected. It is possible to achieve economicalization.

FIG. 3 shows a block diagram of still another embodiment of the present invention, in which 41 is a terminal having one telephone 32, 42 is a terminal having two or more parent and child telephones 32, each of which has It is connected to the subscriber line 2 via an interface device 31.

Also, the interface device 31 has A1 to AI and Am, Am
+1 to An, the subscriber line 2 and the switching center 1 are similar to the embodiment shown in FIG.

Further, 33 is a data terminal device.

Telephone 32 indicated by TEL1 of terminal 41 indicated by SUB1
When calling the terminal 42 indicated by SUB2 from SUB2 to make a phone call, if the telephone 32 indicated by TEL2 is busy and the telephone 32 indicated by TEL3 is empty, the off-hook status signal of the telephone TEL1 is sent as described above. The interface device A1 notifies the exchange 1 and establishes a channel by receiving the channel designation information.

When the number of the called party is dialed from the telephone TEL1, the exchange 1 determines that the called party is the terminal SUB2.

At exchange 1, terminal SUB2 is connected to telephones TEL2 and TEL3.
, and as mentioned above, the telephone TEL
3 is empty, so the empty channel on subscriber line 2 is captured and interface device A
A request signal is sent to m+1, a status signal of the telephone TEL3 is requested, the telephone TEL3 confirms the on-hook state, that is, the incoming call ready state, and sends an empty channel number to the interface device Am+1.

Through the above operations, a channel is established between each of the telephones TEL1 and TEL3 with the switching center 1, and switching operations such as sending out a ring tone and a connection operation are performed, and a telephone conversation becomes possible when the telephone TEL3 responds.

For subscribers who have parent and child telephones, such as the aforementioned terminal SUB2, there is an advantage that telephones TEL2 and TEL3 can be used independently, and in this case, it is desirable to charge for the terminal rather than for the telephone. In such cases, a storage device that indicates the correspondence between terminals and telephone numbers in the control device of the switching center is used, and charges for multiple telephones of the same terminal are written to the charging storage device of that terminal. It can be executed with

The present invention is not limited to the above-described embodiments, but can be modified in various ways, and the transmission method on the subscriber line may be time division multiplexing or frequency division multiplexing by converting PCM, PAM, etc. method etc. can be adopted.

It is also possible to fixedly allocate channels on subscriber lines to terminals on a one-to-one basis.

However, if this channel allocation is done dynamically through communication with the switching center, the utilization efficiency of subscriber lines will be further increased.

As explained above, the present invention multiplexes subscriber lines,
Terminals with functions such as address selection and transmission/reception of control signals are connected in an automatic manner, and a switching center allocates channels on the subscriber line so that information and calls can be exchanged between the terminals. There is no need to install subscriber accommodation terminals in the exchange, making it easier to downsize the exchange and increase the number of terminals it can accommodate.

Also, because the subscriber lines are integrated and used dynamically, economical construction and operation are possible.

In addition, in the embodiment shown in FIG. 3, multiple telephones in a terminal with the same number can independently make and receive calls, which has the advantage of reducing unfinished calls and improving service. be.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are block diagrams of essential parts of respective embodiments of the present invention. 1 is an exchange, 2 is a subscriber line, 3 is a terminal, 11 is a communication path device, 12 is a signaling device, 13 is a control device, 21 is a communication line,
22 is a clock line, 23 is a signal line, 24 is an address line,
31 is an interface device, and 32 is a telephone set.

Claims (1)

[Claims] 1. A system in which subscriber lines between an exchange and a terminal are multiplexed, and the terminal having functions such as address selection and control signal transmission/reception is attached to the multiplexed subscriber line. connect to,
The switching center allocates a channel on the subscriber line based on the communication between the switching center and the terminal, and allows information exchange and communication between the terminals to be performed using the allocated channel. subscriber line multiplexing system. 2. The subscriber line multiplexing system according to claim 1, wherein channel assignment on the subscriber line is performed by sending and receiving terminal address signals and control signals.