JPH08331130A - Method and device for tandem connection of time division private branch exchange in atm network - Google Patents

Abstract

PURPOSE: To eliminate delay due to cell formation in the case that tandem connection is formed in a time division private branch exchange (subsequently, it is called PBX) system which assembles a network with an ATM network. CONSTITUTION: The PBXs 10, 20 and 30 which assemble the network with the ATM network are provided with ATM interfaces 11, 21 and 31 and call assembling/disassembling circuits (subsequently, it is called CLAD) 12, 13, 22 and 32. Also, they are provided with packet assembling/disassembling circuits (GWPAD) 18, 23 and 33 which transfer inter-PBX control information. Moreover, the PBX 10 is provided with a CPU14 which discriminates connection whether it is the tandem connection or the local connection, and an ATM interface circuit 11 which transfers a cell signal to the PBX of a transfer destination when it is the tandem connection, and to the CLADs 12, 13 when it is the local transfer according to the instruction of the CPU14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem connection method and apparatus for a private branch time division exchange in an ATM class.

[0002]

2. Description of the Related Art When a tandem connection is made through a relay station in a conventional private branch exchange system in an ATM network,
As shown in FIG. 3, the relay station has a cell assembling / disassembling circuit for connecting to each private branch exchange, but since it does not have a cell switching means, it comes from the private branch exchange of the transfer source. The decomposed cell signal is once decomposed into a TDM signal by the cell assembling / disassembling circuit of the relay station and is connected to the cell assembling / disassembling circuit for transfer to the transfer destination private branch exchange by the TDSW, and again by the cell assembling / disassembling circuit. A general method is to assemble a cell signal and transfer it to a private branch exchange.

[0003]

When a tandem connection is made via a relay station in a private branch exchange system that forms a network via a conventional ATM network, a cell signal coming from a private branch exchange of a transfer source is relayed to the relay station. The cell assembling / disassembling circuit once decomposed into a TDM signal, and the cell assembling / disassembling circuit for transferring again to the transfer-destination private branch electronic exchange again assembled and transferred to the transfer-destination private branch electronic switch, However, there is a drawback that the relay station causes a cell delay and deteriorates the call quality.

An object of the present invention is to reduce a cell-forming delay due to cell assembly / disassembly of a private branch electronic exchange in a private branch electronic exchange system which forms a network through an ATM network and does not deteriorate the call quality when the tandem connection is performed. A tandem connection method and its device are provided.

[0005]

A tandem connection method for a private branch time-division switch in an ATM network according to the present invention comprises a plurality of line circuits tandemly connected to an ATM line and one-to-one connected with a telephone terminal. In a tandem connection method for a private time division exchange having a time division switch and a central processing unit for exchange control, a cell header containing ATM cell address information for specifying a transfer destination is included in control information between the central processing units of the private time division exchange. A is added to assemble and transmit a cell signal, and specifies control information between the central processing units of the transfer destination among the cell signals received from the ATM line.
A step of identifying a cell signal having a TM cell address, decomposing it into a control signal, and assembling / disassembling a control packet for interfacing with a central processing unit, and connecting with a time division switch of a private branch time division exchange, From the step of assembling / disassembling the voice signal into cells and transmitting the cell signals received from the ATM line into TDM signals and transmitting to the time division switch, and the result of the control packet assembly and cell assembly, AT as an ATM signal including a cell header based on an instruction from the central processing unit
In addition to interfacing with the M line, the transfer destination is recognized from the ATM signal received from the ATM line based on the ATM cell address information included in the cell header, and when a relay connection is made, the ATM line is transferred to another private branch time division switch for transfer. Further, when the call is received at the own station, there is a step of transferring a cell signal including ATM cell address information for cell decomposition and control packet decomposition.

The tandem connection device of the private branch time-division exchange in the ATM network of the present invention includes a plurality of line circuits tandemly connected to the ATM line and one-to-one with the telephone terminal, and a time-division switch. In a tandem connection device of a private time-division exchange having a central processing unit for switching control, a cell header including ATM cell address information for specifying a transfer destination is added to control information between the central processing units of the private-division time-division exchange. A cell signal having an ATM cell address for identifying control information between transfer destination central processing units is identified from among the cell signals received from the ATM line while the signals are assembled and transmitted, and the cell signal is decomposed into a control signal for central processing. Control packet assembly / interface to device
By connecting the disassembly circuit and the time division switch of the local time division exchange, the voice signal from the time division switch is assembled into a cell and transmitted, and the cell signal received from the ATM line is disassembled into a TDM signal, which is converted into a time division switch. Based on the cell assembling / disassembling circuit to be sent out and the result of the control packet assembling and the cell assembling, it interfaces with the ATM line as an ATM signal including the cell header based on the instruction of the central processing unit, and from the ATM signal received from the ATM line to the cell header. The transfer destination is recognized by the included ATM cell address information, and when a relay connection is made, it is transferred to another private branch time division switch on the ATM line for transfer, and when it is called to the local station, cell disassembly and control packet disassembly, It has an ATM interface for transferring cell signals including ATM cell address information.

[0007]

According to the present invention, the transfer destination of the control information is specified in the voice signal from the time division switch of the private branch time division exchange.
A cell header including TM cell address information is added to
It is assembled into a TM cell and sent as an ATM signal to the ATM line.

A cell including the ATM cell address information is recognized from the ATM signal received from the ATM line to the transfer destination by the ATM cell address information contained in the cell header, and to the other private branch time division exchange via the ATM line when relaying is performed. Transfer the signal. In the case of an incoming call to the own station, cell disassembly and control packet disassembly are performed, and connection is made to a specific telephone terminal via a time division switch according to ATM cell address information.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings.

FIG. 1 is a system configuration diagram of an embodiment of the present invention, and FIG. 2 is a cell signal format.

In FIG. 1, the private branch electronic exchange 10, the private branch electronic exchange 20, and the private branch electronic exchange 10 and the private branch electronic exchange 30 have an ATM line 40 and an ATM line 41, respectively.
Connected through. The private branch exchange 10 analyzes the cell header and discriminates whether it is addressed to its own station or another station to relay A
TM interface 11 and time division switch (hereinafter TD
Voice signal (TDM signal) coming from 15)
Are assembled into cells and transferred to the ATM interface 11,
VPI specified by a central processing unit (hereinafter referred to as CPU) 14 by a cell signal coming from the TM interface 11
The cell signal whose VCI value is set in the VPI field / VCI field is decomposed into a TDM signal and TDSW15
Cell assembling / disassembling circuit (hereinafter CLA)
A packet assembling / disassembling circuit that assembles a message, which is a control signal of the CPU 14 and the CPU 14 into a cell, transfers the cell signal to the ATM interface 11, decomposes the cell signal coming from the ATM interface 11 into a message, and transfers the message to the CPU 14. (Hereinafter referred to as GWPAD) 1
Eight. The local electronic exchanges 20 and 30 also have the same configuration. CLAD 12, 13, 2 here
Reference numerals 2 and 32 denote the TDM signal in the VPI field / VCI field respectively VPI2 / VCI2 and VPI3 / VC.
I2, VPI1 / VCI2, VCI4 / VCI2 are set to assemble into a cell signal, and GWPAD23,
33 indicates the messages of the CPUs 24 and 34 in the VPI field / VCI field and VPI1 / VCI1, respectively.
It is assumed that VPI4 / VCI1 is set and assembled into a cell signal. Further, in the GWPAD 18, when the message of the CPU 14 is transferred to the private branch exchange 20, VPI2 / VCI1 is set in the VPI field / VCI field, and when it is transferred to the private branch exchange 30, VPI field / VC is set.
Assume that VPI3 / VCI1 is set in the I field to assemble a cell.

Here, in the cell ATM interface circuit 11, the V of the cell signal arriving via the ATM line 40 in advance.
PI field / VCI field is VPI1 / VCI
If it is 1, the VPI field / VCI field of the cell signal arriving via the ATM line 41 is VPI4 /
If it is VCI1, the cell signal is transferred to the GWPAD 18, and the VPI field / VCI field of the cell signal coming from the GWPAD 18 is VPI2 / VC.
If it is I1, the private branch exchange 2 via the ATM line 40
0, VPI3 / VCI1 is transferred to the private branch exchange 30 via the ATM line 41, and CLAD12,
The cell signals assembled in 13 are sent to the ATM line 4 respectively.
It is set to transfer to the private branch exchanges 20 and 30 via 0 and 41.

In the ATM interface 21, the ATM
VPI field of cell signal arriving via network 40 /
GWP if the VCI field is VPI2 / VCI1
To the AD 23, the cell signal assembled by the GWPAD 23 and the cell signal assembled by the CLAD 22 are sent to the ATM line 40.
It is set so that data is transferred to the private branch exchange 10 via the ATM network 31.
VPI field / VCI of cell signal arriving via
GWPAD3 if the field is VPI3 / VCI1
Cell signal and CLAD assembled by GWPAD33 to 3
The cell signal assembled in 32 is set to be transferred to the private branch exchange 10 via the ATM line 41.

Further, the extension telephone 17 is connected to the private branch exchange 10 via the line circuit 16, the extension telephone 27 is connected to the private branch exchange 20 via the line circuit 26, and the extension telephone 3 is connected.
7 are housed in the private branch exchange 30 via line circuits 36, respectively.

First, when the extension telephone 27 housed in the private branch exchange 20 makes a call to the extension telephone 17 housed in the private branch exchange 10, the person who handles the extension telephone 27 goes off-hook and then the extension telephone 17 number is entered. Dial. The CPU 24 of the private branch exchange 20 is the extension telephone 2
When recognizing that the call is to the extension telephone 17 accommodated in the private branch exchange 10, the CPU 24 calls the extension telephone 27 to the extension telephone 17 of the private branch exchange 10 when the connection selection signal coming from 7 is recognized. And when the voice signal of the extension telephone 27 is assembled into a cell signal, VPI1 is added to the VPI field / VCI field of the cell signal.
Generates a message notifying that / VCI2 is set and transfers it to the GWPAD 23. C for GWPAD23
The message transferred from the PU 24 is transferred to the private branch exchange 1
VPI field / V to transfer to CPU 14 of 0
VPI1 / VCI1 is set in the CI field, assembled into a cell signal, and transferred to the ATM interface 21. A
The TM interface 21 receives the cell signal received from the GWPAD 23 via the ATM line 40 and the private branch exchange 10
To the ATM interface 11. The ATM interface 11 transfers the received cell signal to the GWPAD 18 because the VPI field / VCI field of the received cell signal is VPI1 / VCI1. G
The WPAD 18 decomposes the received cell signal into a message and transfers it to the CPU 14. The CPU 14 analyzes the message and confirms that the extension telephone 27 of the private branch exchange 20 is calling the extension telephone 17 of the own station, and that the VPI field / VCI field of the cell signal of the voice signal coming from the private branch exchange 20 is VPI1 /. Recognize that it is VCI2. Then, the CPU 14 controls the ATM interface 11 to receive the V coming from the private branch exchange 20.
The cell signal of PI1 / VCI2 is set to be transferred to the CLAD 12. Further, the CPU 14 has a VPI field / VCI field of VPI1 /
It is instructed to decompose a VCI2 cell signal into a TDM signal. The CLAD 12 decomposes a VPI1 / VCI2 cell signal coming from the ATM interface 11 into a TDM signal and transfers the TDM signal to the TDSW 15, and TDSW1.
The TDM signal arriving from 5 is set to VPI field / VCI.
The VPI2 / VCI2 is set in the field, assembled into a cell signal, and transferred to the ATM interface 11. Further, the CPU 14 calls the extension telephone set 17. Thereafter, the CPU 14 generates a message notifying that the extension telephone 17 is being called and that the VPI field / VCI field of the cell signal is set to VPI2 / VCI2 when assembling the voice signal of the extension telephone 17 into a cell signal. Then, the transfer to the private branch exchange 20 is added and the transfer is made to the GWPAD 18. GWPAD
At 18, the VPI is used to transfer the message transferred from the CPU 14 to the GWPAD 23 of the private branch exchange 20.
VPI2 / VCI1 is set in the field / VCI field to assemble into a cell signal and the ATM interface 11
Transfer to. GWPAD for ATM interface 11
VPI field / VCI of cell signal received from 18
Since the field is VPI2 / VCI1, the received cell signal is transferred to the ATM interface 21 of the private branch exchange 20 via the ATM line 40. The ATM interface 21 of the private branch exchange 20 converts the cell signal arriving via the ATM line 40 into the VPI field / V.
Since the CI field is VPI2 / VCI1, the received cell signal is transferred to the GWPAD 23. GWPA
At D23, the received cell signal is decomposed into a message, and C
Notify the PU 24. The CPU 24 analyzes the message received from the GWPAD 23 and recognizes that the VPI field / VCI field of the cell signal which transfers the voice signal coming from the private branch exchange 10 is VPI2 / VCI2. Then, the CPU 24 instructs the CLAD 22 to change the VPI field / VCI field to VPI2 /
It is instructed to decompose the VCI2 cell signal into a TDM signal, and also controls the ATM interface 21 to send the AT signal.
A cell signal that arrives via the M line 40 and has a VPI field / VCI field of VPI2 / VCI2 is set to be transferred to the CLAD 22. Further, the CPU 24 controls the TDSW 25 to connect the CLAD 22 and the line circuit 26. The CLAD 22 decomposes the cell signal coming from the ATM interface 21 and having the VPI field / VCI field set to VPI2 / VCI2 into a TDM signal, and transfers the TDM signal to the TDSW 25. VPI1 / VCI2 is set in the VCI field to assemble into a cell signal and transfer to the ATM interface 21 is started.

Thereafter, when the person who handles the extension telephone 17 responds and the extension telephone is taken off-hook, the CPU 14 of the private branch exchange 10 recognizes that the extension telephone 17 has answered,
The TDSW 15 is controlled to control the CLAD 12 and the line circuit 16
To connect the extension telephone set 27 and the extension telephone set 17 to a call state.

When the extension telephone 27 goes on-hook at the end of the call, the CPU 24 recognizes that the communication between the extension telephone 27 and the extension telephone 17 has ended. Then the CPU 24 is AT
The CPU 14 of the private branch exchange 10 is notified via the M line 40 that the telephone call between the extension telephone 27 and the extension telephone 17 has ended. Further, the CPU 24 controls the TDSW 25 to disconnect the CLAD 22 and the line circuit 26,
Instruct the AD 22 to stop assembling / disassembling the cell signal. When the CLAD 22 receives an instruction to stop the cell assembly / disassembly from the CPU 24, the CLAD 22 stops the cell signal assembly / disassembly.

The CPU 14 of the private branch exchange 10 is a CPU
The message received from 24 through the ATM line 40 is analyzed, and it is acknowledged that the extension telephone 27 and the extension telephone 17 are restored. Then TDSW15 is controlled and CLAD
12 and the line circuit 16 are disconnected, and further CLAD
12 is instructed to stop the assembly / disassembly of cell signals.
When the CLAD 12 receives the instruction to stop the cell assembly / disassembly from the CPU 14, the CLAD 12 stops the cell signal assembly / disassembly.

Further, when the extension telephone 27 accommodated in the private branch exchange 20 makes a call to the extension telephone 37 accommodated in the private branch exchange 30, the operator of the extension telephone 27 goes off-hook and then the extension telephone 37 is called. Dial the number. When the CPU 24 of the private branch exchange 20 analyzes the connection selection signal coming from the private branch telephone 27 and recognizes that the call is to the private branch telephone 37 accommodated in the private branch electronic exchange 30, the CPU 24 causes the private branch telephone 27 to call the private branch electronic exchange. When the call is sent to the extension telephone 37 of 30 and the voice signal of the extension telephone 27 is assembled into a cell signal, V
VPI1 / VCI in the PI field / VCI field
A message for notifying that 2 is set is generated, and the same is notified to the CPU 14 of the private branch exchange 10.
The CPU 14 folds the message, and the private branch exchange 2
0 extension call from the extension telephone 27 to the extension telephone 37 of the private branch exchange 30 and the VPI field / VCI field of the cell signal for transferring the voice signal coming from the private branch exchange 20 is VPI1 / VCI2. When the CFU 14 recognizes, the extension telephone 27 of the private branch exchange 20 to the extension telephone 3 of the private branch exchange 30.
7 to generate a message notifying that VPI1 / VCI2 is set in the VPI field / VCI field of the cell signal for transferring the voice signal coming from the private branch electronic exchange 20. It is transferred to GWPAD18 with the addition of the transfer to 30. In the GWPAD 18, the VPI field / VCI field is set to V in order to transfer the message transferred from the CPU 14 to the GWPAD 33 of the private branch exchange 30.
Set PI3 / VCI1 to assemble to cell signal, ATM
Transfer to the interface 11. At the ATM interface 11, the VPI of the cell signal received from the GWPAD 18
Since the field / VCI field is VPI3 / VCI1, the received cell signal is transferred to the ATM interface 31 of the private branch exchange 30 via the ATM line 41. The ATM interface 31 of the private branch exchange 30 uses the VP for the cell signal coming through the ATM line 41.
I field / VCI field is VPI3 / VCI1
Therefore, it is transferred to the GWPAD 33. GWPAD
33 decomposes the cell signal received in 33 into a message,
Notify U34.

The CPU 34 analyzes the message transferred from the GWPAD 33, and in order to transfer from the extension telephone 27 of the private branch exchange 20 to the extension telephone 37 of its own station and to transfer the voice signal coming from the private branch exchange 20. It is recognized that the VPI field / VCI field of the cell signal is VPI1 / VCI2. Then CP
U34 controls the ATM interface 31 to
The VPI1 / VCI2 cell signal arriving via the network 41 is set to be transferred to the CLAD 32. Also CPU
34 is VPI field / VC for CLAD 32
The cell signal whose I field is VPI1 / VCI2 is T
Instructs to decompose into a DM signal. CLAD32 is A
VPI1 / VCI coming from TM interface 31
2 cell signal is decomposed into a TDM signal and transferred to the TDSW 35, and the TDM signal coming from the TDSW 35 is converted into a VPI field / VCI field by VPI4 / VC.
The I2 is set, assembled into a cell signal, and transferred to the ATM interface 31. Further CPU34
Calls the extension telephone 37. After that, the CPU 34 informs that the extension telephone 37 is calling and that the extension telephone 37
When assembling the voice signal of (1) into a cell signal, a message notifying that VPI4 / VCI2 is set in the VPI field / VCI field is generated and transferred to the GWPAD 33. In the GWPAD 33, the message transferred from the CPU 34 is set in the VPI field / VCI field to VPI4 / VCI1 and assembled into a cell signal,
Transfer to the ATM interface 31. The ATM interface 31 transfers the cell signal received from the GWPAD 33 to the ATM interface 11 of the private branch exchange 10 via the ATM line 41. ATM interface 1
In 1, the VP of the cell signal arriving via the ATM line 41
I field / VCI field is VPI4 / VCI1
Therefore, the received cell signal is transferred to the GWPAD 18. The GWPAD 18 decomposes the received cell signal into a message and transfers it to the CPU 14 of the private branch exchange 10. In the CPU 14, the CPU of the private branch exchange 30
The message received from 34 is analyzed, and the extension telephone 37
That the extension telephone 37 is calling when recognizing that the VPI field / VCI field of the cell signal for transferring the voice signal coming from the private branch exchange 30 is VPI4 / VCI2 In a similar manner, the CPU 24 of the private branch exchange 20 is notified that the VPI field / VCI field of the cell signal for transferring the voice signal coming from the private branch exchange 30 is VPI4 / VCI2. Further CPU
Reference numeral 14 controls the ATM interface 11 to send a cell signal coming from the private branch exchange 20 whose VPI field / VCI field is VPI1 / VCI2 to the private branch exchange 30 and the VPI coming from the private branch exchange 30.
The field / VCI field is set to transfer the cell signal having VPI4 / VCI2 to the private branch exchange 20. The CPU 24 is the CPU 14 of the private branch exchange 10.
Analyzes the message received from the local electronic exchange 10
Cell signal VP for transferring voice signals coming from
I field / VCI field is VPI4 / VCI2
Recognize that Then, the CPU 24 makes CLAD2
2, the VPI field / VCI field is VP
A cell signal instructing to decompose a cell signal of I4 / VCI2 into a TDM signal, and controlling the ATM interface 21 to have a VPI field / VCI field of the cell signal coming through the ATM line 40 is VPI4 / VCI2. Is set to be transferred to the CLAD 22.
Further, the CPU 24 controls the TDSW 25 to control the CLAD 22.
And the line circuit 26 are connected. CLAD 22 is a VPI field / VC coming from the ATM interface 21.
The cell signal whose I field is VPI4 / VCI2 is T
Decomposing into a DM signal and transferring to the TDSW 25, and
The TDM signal arriving from the DSW 25 is VPI1 / VCI
2 is set in the VPI field / VCI field to assemble into a cell signal, and transfer to the ATM interface 21 is started.

After that, when the person who handles the extension telephone 37 responds and the extension telephone is taken off-hook, the C for each private branch exchange is changed.
The PU 34 recognizes that the extension telephone 37 has answered, and
The DSW 35 is controlled to connect the CLAD 32 and the line circuit 3C, and the extension telephone set 27 and the extension telephone set 37 are brought into a call state.

When the extension telephone 27 goes on-hook at the end of the call, the CPU 24 recognizes that the communication between the extension telephone 27 and the extension telephone 37 has ended. Then the CPU 24 is AT
The CPU 14 of the private branch exchange 10 is notified via the M line 40 that the telephone call between the extension telephone 27 and the extension telephone 37 has ended. Further, the CPU 24 controls the TDSW 25 to disconnect the CLAD 22 and the line circuit 26. It also instructs the CLAD 22 to stop the assembly / disassembly of cell signals. When the CLAD 22 receives an instruction from the CPU 24 to stop the cell stringing / disassembly, the CLAD 22 stops assembling / disassembling the cell signal.

The CPU 14 of the private branch exchange 10 is a CPU
When analyzing the message received from 24 through the ATM line 40 and recognizing that the extension telephone 27 and the extension telephone 37 are restored, the CPU 14 sends the extension telephone 27 and the extension telephone to the private branch exchange 30 via the ATM line 41. Notify that the telephone call of the telephone 37 has ended.

The CPU 34 of the private branch exchange 30 is a CPU
When the message received from the I4 through the ATM line 41 is analyzed and it is recognized that the extension telephone 27 and the extension telephone 37 have been restored, the TDSW 35 is controlled and the CLAD 32 is controlled.
Then, the line circuit 36 is disconnected, and the CLAD 32 is instructed to stop the assembly / disassembly of the cell signal. CLAD3
When the CPU 2 receives an instruction to stop cell assembly / disassembly from the CPU 34, it stops cell signal assembly / disassembly.

[0025]

As described above, according to the present invention, the AT of the relay station in the switching system in which the ATM network is formed.
Since the M interface is controlled and the tandem connection is performed with the cell signal as it is, there is no need to disassemble the cell signal into a TDM signal and reassemble into the cell signal at the relay station, and the celling delay does not occur. The effect is that it can be prevented.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is a format of a cell signal.

FIG. 3 is a system configuration diagram of a conventional technique.

[Explanation of symbols]

 10, 20, 30 Yokouchi electronic exchange 11, 21, 31 ATM interface 12, 13, 22, 32 CLAD 18, 23, 33 GWPAD 14, 24, 34 CPU 15, 25, 35 TDSW 16, 26, 36 Line circuit 17, 27, 37 Telephone terminal 40, 41 ATM line 100, 110, 120 Private branch exchange 101, 102, 111, 121 CLAD 103, 112, 122 CPU 104, 113, 123 TDSW 114, 124 Line circuit 115, 125 Telephone terminal

Claims (2)

[Claims] 1. A tandem connection of a private time-division exchange having a plurality of line circuits tandemly connected to an ATM line and connected to telephone terminals in a one-to-one correspondence, a time-division switch, and a central processing unit for exchange control. In the method, a cell header including ATM cell address information for specifying a transfer destination is added to control information between central processing units of the private branch time division switch, and a cell signal is assembled and transmitted,
Among the cell signals received from the ATM line, a control signal assembly for identifying a cell signal having an ATM cell address for specifying control information between the transfer destination central processing units, decomposing it into control signals, and interfacing with the central processing unit / Step of disassembling and connecting to the time division switch of the local time division switch, assemble the voice signal from the time division switch into a cell and send it out, decompose the cell signal received from the ATM line into a TDM signal, and time division From the step of assembling / disassembling the cell to be sent to the switch and the result of the control packet assembling and the cell assembling, the interface with the ATM line as the ATM signal including the cell header based on the instruction of the central processing unit, and the ATM
The transfer destination is recognized from the ATM signal received from the line based on the ATM cell address information included in the cell header, and when a relay connection is made, the AT is transferred to another private branch time division switch.
The method further comprises the step of transferring a cell signal containing ATM cell address information for cell disassembly and control packet disassembly when the call is received on the M line or to the own station.
Tandem connection method of private branch time division exchange in TM network. 2. A tandem connection of a private time division exchange having a plurality of line circuits tandemly connected to an ATM line and one-to-one with a telephone terminal, a time division switch, and a central processing unit for exchange control. In the device, a cell header including ATM cell address information for specifying a transfer destination is added to the control information between the central processing units of the private branch time division switch, and a cell signal is assembled and transmitted,
Among the cell signals received from the ATM line, a control signal assembly for identifying a cell signal having an ATM cell address for specifying control information between the transfer destination central processing units, decomposing it into control signals, and interfacing with the central processing unit / Disassembled circuit is connected to the time-division switch of the local time-division switch, the voice signal from the time-division switch is assembled into a cell and transmitted, and the cell signal received from the ATM line is decomposed into a TDM signal, and the time-division switch is connected. And a cell assembling / disassembling circuit to be sent to the ATM circuit, and based on the result of the control packet assembling and the cell assembling, as an ATM signal including a cell header based on an instruction from the central processing unit, and interface with an ATM line.
The transfer destination is recognized from the ATM signal received from the line based on the ATM cell address information included in the cell header, and when a relay connection is made, the AT is transferred to another private branch time division switch.
A tandem private branch time-division switch in an ATM network characterized by having an ATM interface for transferring a cell signal containing ATM cell address information for cell disassembly and control packet disassembly when an incoming call is made to an M line or to its own station. Connection device.