JPH04304751A - Private automatic branch exchange - Google Patents

Abstract

PURPOSE:To attain effective utilization of D and B channels for communication between the private automatic branch exchange and a data terminal equipment of an extension telephone set. CONSTITUTION:D channel switch sections 104, 106, 112 for control signal are provided with traffic management sections 103, 105, 111 monitoring congestion of traffic respectively, a call processing section 101 selects a channel switch section 102 and a D channel switch section 104 or the like to select the D channel or the B channel for the path, and when D channel communication is available at a communication speed included in a call signal, demultiplexer/ multiplexer sections 108, 109, 114 implement demultiplexing/multiplexing, the control signal and the data are subject to packet multiplexing via the D channel to implement communication, and when the communication is disabled through the D channel or a large delay is caused in the control data communication, the B channel is selected for the communication.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a control channel (hereinafter referred to as D channel) at a communication speed included in a calling signal.
The present invention relates to an automatic private branch exchange having a function of selecting either the B channel or the information channel (hereinafter referred to as the B channel).

0002

2. Description of the Related Art With the recent development of digital signal processing technology, automatic branch exchanges have come to switch digital signals rather than analog signals.

FIG. 4 shows an example of a conventional private automatic branch exchange, and is a block diagram of a case where three extension telephones are accommodated.

As shown in the figure, the main device 100 has a call processing section 1.
01, has a communication path switch section 102, a D channel switch section 104, and the extension control devices 110, 115 have D channel switch sections 106, 112, a demultiplexing section 108,
It has 109,114. This extension control device 110,1
15 is connected to a plurality of extension telephones 116, 117, 118 and data terminals 119, 120, 121, and controls the LEDs, bells, etc. of the extension telephones connected in units of extension circuits. For example, the extension telephone 116 and the extension control device 110
The line is connected by a pair of twisted pair wires, and this line has two information channels (B channel) for information signals and a control channel (D channel) for control signals that control the telephone. 2B+D channels are generally configured.

[0005] Separation/multiplexing section 108 in extension control device 110
, 109 separate and multiplex these B channels and D channels, and the B channel is connected to the communication path switch section 102, and the D channel is connected to the main device via the D channel switch section 106 of the extension control device 110, for example. It is configured between the D channel switch section 104 in the D channel switch section 100 and enables packetized control data to be communicated.

As for the communication method, the extension telephone is equipped with a digital port such as RS-232C in addition to voice communication, and (1) the call processing section 101 is connected to the communication path switch section 10.
2, communication between data terminals can be performed using the B channel. Also, as a line control procedure while it is a data terminal, in addition to manual dialing by button operation of the extension telephone, V. 25
Equipped with modem control commands such as BIS, it enables automatic calling and line disconnection from data terminals.

(2) In private branch exchanges that apply the 2B+D channel configuration described above, which is the user network interface standard for integrated digital service networks that has been internationally standardized in recent years, the D channel described above is packet-multiplexed to transmit control signals. In addition, communication data can be transmitted and received between the data terminals.

[0008]

[Problem to be Solved by the Invention] However, in the conventional method (1) as described above, the B channel is also used for data communication between data terminals, so it is difficult to send a busy tone, make a voice call to an extension, etc. In order to provide a service that requires two B channels, three or more B channels are required, which increases the cost of the demultiplexer.

[0009]Also, in the conventional method (2) mentioned above, data communication is possible using the D channel, but the line control procedure between the digital port and the data terminal is standardized for line control of the telephone network. Because the system uses a standard modem control procedure, channel selection must be done manually by pressing buttons on the telephone extension. Furthermore, since the user does not have a means to know information about the D channel traffic up to the destination extension, the D channel has the problem that it is not possible to select a channel for each call depending on the traffic including control signals. had.

The present invention solves the problems of each of the conventional communication systems, selects a control or information channel based on the communication speed included in the calling signal, and connects the private automatic branch exchange and the data terminal of the extension telephone. The purpose is to make effective use of communications.

[0011]

[Means for Solving the Problems] The present invention provides a communication path switch unit that performs switching of information channels, a call processing unit that controls the communication path switch unit and performs logical switching processing, and a call processing unit that performs logical switching processing by controlling the communication path switch unit. a plurality of control channel switch sections that form control channels for performing packet communication between the telephone and the extension telephone, a traffic management section that monitors traffic congestion in the control channel switch section, and the above-mentioned information between the extension telephone and and a demultiplexing unit which separates the multiplexed control channel signal, connects the information channel to the communication path switch unit, and connects the control channel to the control channel switch unit, and an extension telephone equipped with a data communication port. When it receives a calling signal from a terminal connected to the data communication port, it analyzes the destination number included in the calling signal and determines the route to the destination extension based on the traffic congestion on the control channel route. The feature is that communication is performed by selecting either a control channel or an information channel.

0012

[Operation] According to the present invention, since the D channel is used for data communication between extensions, it is possible to simultaneously use voice services and data communication using the 2B channel, and
The system examines the traffic on the D-channel route and determines whether D-channel communication is possible within the range where there is no large delay in telephone control signal communication based on the communication speed requested by the terminal and the current traffic. can select the optimal channel for each call without being conscious of channel selection.

[0013]

[Embodiments] Examples of the present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram of a private automatic branch exchange according to an embodiment of the present invention in which three extension telephones are accommodated. In the figure, 103, 105, and 111 are traffic management units, and other symbols indicate the same units as in the conventional example shown in FIG. As shown in the figure, the main device 100 includes a call processing section 101,
Communication path switch section 102, D channel switch section 10
In addition to 4, it has a traffic management section 103, and extension control devices 110 and 115 have D channel switch sections 106 and 1.
12. In addition to demultiplexing/multiplexing units 108, 109, 114, it has traffic management units 105, 111, and each extension control device connects a plurality of extension telephones 116, 117, 118.

[0015] These multiple extension control devices 110, 11
5 is a unit for adding extension lines, and each extension control device controls the LED, bell, etc. of the extension telephone. For example, the extension telephone 116 and the extension control device 110 are connected by a pair of twisted pair wires, and this line has two B channels and a D channel for control signals for controlling the telephone, making 2B+D channels. is generally configured.

Further, these channels are separated and multiplexed by demultiplexing units 108 and 109 in the extension control device 110, and the B channel is connected to the communication path switch unit 102, and the D channel is connected to the D channel switch unit 106.
, 112 and the D channel switch unit 104 in the main device 100 using packet communication.
16, 117, and 118 to communicate control data.

In this embodiment, especially the traffic management section 10
3, 105, and 111 are provided, and the number of switched packets per unit time is monitored by the D channel switch units 104, 106, and 112, respectively, to monitor the degree of congestion.

In addition to voice calls, the extension telephones 116, 117, and 118 are equipped with digital ports such as RS-232C, and in addition to making manual calls by operating buttons on the extension telephones, data terminals 119,
From 120 and 121, automatic calling, line disconnection, etc. can be performed by modem control commands.

Furthermore, there are two types of data paths between these data terminals: circuit switching in which the call processing section 101 switches the B channel by switching the communication path switch section 102, and packet switching in which the D channel is set up as a partial call. is available.

FIG. 2 is a sequence diagram of a procedure for starting communication between data terminals using the D channel in FIG. In the figure, (300) to (310) represent each step number. In this example, the data terminal 119 makes a call to the data terminal 121 using the modem control command described above, and the data terminal 119 sends a call signal including the destination number (of the data terminal 121) and the requested communication speed to the extension telephone 111. (300), and the extension telephone 116 sends a message to the call processing unit 10.
1 is converted into a packet in a form that can be recognized, and transmitted to the call processing unit 101 via the D channel (301).

[0021]Then, the call processing unit 101 compares the requested communication speed of the sent calling signal with the maximum communication speed of the D channel, and if it is smaller than the maximum communication speed of the D channel, sends the destination number (DT) to the extension telephone 116. Notify (302
).

[0022] The extension telephone 1 that received this destination number
16 inserts the communication speed information confirmed by the above-mentioned procedure into a call request packet, and sends the packet on the D channel with the extension telephone 118 as the destination (call request) (303).

[0023] Upon receiving this call request, the D channel switch section 106 refers to the D channel traffic information for the destination managed by the traffic management section 105, and determines whether communication is possible based on the requested communication speed information included in the call request. If possible, the call request is sent to the next D channel switch section 104 (304).

The D channel switch section 112 also operates in a similar manner. The extension telephone 118 that received the call request returns an acknowledgment (ACK) to the extension 116 (307). the extension telephone 116 that received the acknowledgment;
sends a connection notification to the data terminal 119 (309), and thereafter the data terminals 119 and 121 enter a communication state using the D channel (308, 310).

FIG. 3 is a message sequence diagram of a communication start procedure when communicating on the B channel. In the figure, (400) to (413) represent each step number. For example, when the data terminal 119 makes a call to the data terminal 121 using the modem control command described above, the requested communication speed of the data terminal 119 is smaller than the maximum communication speed of the D channel, but the D channel switch section 104 and the D channel switch section 112 This is a case where a high-speed virtual call (a virtual communication path in packet communication) has already been set up during the period, and the communication speed cannot be provided.

In this case, the D channel switch section 10
4 returns a negative response (NAK) to the extension telephone 116 in response to the call request packet (405). The extension telephone 116, which received the negative response indicating that communication on the D channel is not possible, then transmits a call request (DT) for setting the B channel to the call processing unit 101 (407).

The call processing section 101 that has received the call request transmits the call request to the destination extension telephone 118 (408). The extension telephone 118 that received the call request responds with an acknowledgment (A
CK) is returned to the call processing unit 101 (409). The call processing unit 101 that has received the acknowledgment responds to the call path switch unit 1.
02, the B channel between the extension telephones 116 and 118 is connected, and an acknowledgment (ACK) is returned to the extension telephone 116 (410). The extension telephone 11 that received the positive response
6 sends a connection notification to the data terminal 119 (412),
Thereafter, the data terminals 119 and 121 enter a communication state using the B channel (411, 413).

[0028]

[Effects of the Invention] As explained above, the private automatic branch exchange of the present invention does not require an interface between an extension telephone and a data terminal, or new commands, and can use conventional modem control commands. does not require awareness of channel selection. Since the time for which the B channel is used for data communication can be shortened, it becomes possible to simultaneously use, for example, an audio service that uses two B channels.

In addition, since the channel is automatically selected so that the traffic congestion on the D channel route to the destination telephone is within a certain value, the delay of call control signals due to simultaneous communication with data can be kept below a certain level. This has a significant effect on effective channel utilization and improved responsiveness of telephone control during simultaneous data and voice communication.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a private automatic branch exchange according to an embodiment of the present invention.

FIG. 2 is a sequence diagram of a procedure for starting communication between data terminals using a D channel.

FIG. 3 is a message sequence diagram of a communication start procedure when communicating on a B channel.

FIG. 4 is a block diagram of a conventional private automatic branch exchange.

[Explanation of symbols]

100...Main device, 101...Call processing unit, 102...
Communication path switch section, 103, 105, 111... Traffic management section, 104, 106, 112... D channel switch section, 108, 109, 114... Separation/multiplex section, 110, 115... Extension control device, 11
6,117,118...Extension telephone, 119,120
, 121...Data terminal.

Claims (2)

[Claims] Claim 1: A communication path switch section that performs switching of information channels; a call processing section that controls the communication path switch section and performs logical switching processing; The information and control channels are multiplexed between a plurality of control channel switch units that form control channels for communication, a traffic management unit that monitors traffic congestion in the control channel switch units, and an extension telephone. After separating the signals, the information channel is connected to the communication path switch section, and the control channel is composed of a demultiplexing section connected to the control channel switch section, and an extension telephone equipped with a data communication port, and the control channel is connected to the communication path switch section. When a calling signal from a connected terminal is received, the destination number included in the calling signal is analyzed and the route is determined as either a control channel or an information channel based on the traffic congestion on the control channel route to the destination extension. An automatic private branch exchange characterized by selective communication. [Claim 2] If control channel communication is possible at the communication speed included in the calling signal, the control signal and data are packet-multiplexed via the control channel, and if communication is not possible via the control channel, or 2. The private automatic branch exchange according to claim 1, wherein if there is a large delay in control data communication, communication is performed by switching to an information channel.