JP2001053876A - Automatic alternative selective exchange system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely obtain an incoming call by reducing a communication load on a relay network, and preventing the increase of the block rate of call setting. SOLUTION: A simple switchboard 11 holds the number of times of recalling, and sets a condition for judging whether or not recalling should be executed at the time of receiving call release information due to the failure of the call setting from a route solving switchboard 31. The simple switchboard 11 transmits call setting information 51 to which the number of times of recalling is added to the route solving switchboard 31, and updates the held number of times of recalling at the time of receiving call release 52 due to the failure of the call setting from the route solving switchboard 31, and transmits the call setting information 51 to which the updated number of times of recalling is added to the route solving switchboard 31 when the set condition is fulfilled. The route solving switchboard 31 selects fixed routes in prescribed priority order corresponding to the number of times of recalling of the received call setting information 51, and prepares and transmits relay call setting information to the destination of an incoming call indicated by the call setting information 51 based on the selected fixed route.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic detour selection switching system having a signaling (call control) procedure and an automatic detour selection switching method, and more particularly to a route resolution exchange connected to a switching network. It has a fixed route specification table for holding a plurality of fixed routes for each transit exchange in a predetermined priority order, and automatically selects a route to a destination indicated by a received call using the fixed route specification table. And does not have an outgoing route other than the route resolution exchange,
The present invention relates to an automatic detour selection switching system and an automatic detour selection switching method in which a simple exchange having no route resolution capability causes the route resolution exchange to substitute a route for a call from a terminal connected to the simple exchange.

[0002]

2. Description of the Related Art Conventionally, when a failure or the like occurs in a switching network, an automatic detour route is determined so that a calling side and a called side can be reliably connected. As a method of generating the automatic detour, for example, there is a method of automatically calculating the automatic detour.

FIG. 13 is a block diagram showing a schematic configuration of a conventional switching system for automatically calculating an automatic detour route.
In the switching system shown in FIG.
13 and an exchange network including the route resolution exchanges 121 and 142. The switching network has transit exchanges 131 to 133. The simplified exchanges 110 and 122 are directly connected to the route resolution exchanges 121 and 122, respectively. Upon receiving a call setting request for receiving the simple exchange 113 from the directly connected simple exchange 110, the route resolution exchange 121 automatically determines one optimal route from the own route resolution exchange 121 to the simple exchange 113. Then, call setting information including the one optimal route is generated, and call setting is attempted toward the simplified exchange 113 side.

If the call setup fails due to a failure or the like, another one of the alternate routes is automatically calculated again, the call setup information including the one alternate route is generated, and the call is sent to the simplified exchange 113 again. Attempt call setup for At least one terminal is connected to each of the simplified exchanges 110 and 113, and the simplified exchanges 110 and 113 do not perform the process for determining the route, and are directly connected to the route resolution exchanges 121 and 1 respectively.
42 is made to substitute for the processing related to the route determination.

However, in the method of automatically calculating the bypass route, it is necessary to calculate the first optimal route or the subsequent bypass route each time, so that it takes time and the load on the route resolution switch is large. was there. For this reason, when a terminal sets up a call, a plurality of relay route candidates in the switching network to be used are added to the call setting information, and when a failure or the like occurs, the relay route candidates are used sequentially. In some cases, call setting is performed reliably.

For example, FIG. 14 is a diagram showing the configuration of a conventional switching system in which a plurality of relay route candidates are added to call setting information to determine an automatic detour route, and FIG. It is a figure which shows an example of the content of the call setting information which added two or more. The configuration shown in FIG. 14 is a configuration in which the simplified exchanges 110 and 113 shown in FIG. 13 are replaced by terminals 111 and 112, and the route resolution exchanges 121 and 124 directly
Terminals 111 and 112 are accommodated.

As shown in FIG. 15, the call setting information includes
Information such as the originating terminal, the terminating terminal, the required quality information, the call number, the route designation of the relay route 131, and the route designation of the relay route 132 is included. The content of the route specification of the relay route 131 is the route specification via the transit exchanges 122 to 124 as the number of transit “3”, and the content of the route specification of the transit route 132 is the transit exchange 125 and 124 as the transit number “2”. Is a route specification. Therefore, in this case, two route designations are added to the call setting information.

In order to solve the above-mentioned problems, the route-resolving exchanges 121 and 124 hold the route information of the transit exchanges up to the respective destination exchanges as fixed route information. When a route solution request is issued to the solution exchange, the fixed route information is scanned to obtain the route information to the desired terminating exchange, and call setting is quickly and reliably performed based on the route information. There is something to do.

For example, FIG. 16 is a diagram showing the configuration of a conventional switching system in which a route resolution exchange holds fixed route information and determines an automatic detour route using the fixed route information. It is a figure showing an example of the contents of fixed route information which a route solution exchange holds. The configuration shown in FIG. 16 is the same as the configuration shown in FIG. 13 except that the route resolution exchanges 121 and 124 hold fixed route information and determine an automatic bypass route based on the fixed route information. .

[0010] As shown in FIG.
The fixed route information of No. 1 describes a list of the transit exchanges for the transit exchanges 122 to 125 and the destination exchanges which are the simple exchanges 110 and 113. For example, when the transit exchange 123 is the destination exchange, the route is described in the order of transit exchange 122 → 123, and the simple exchange 11
In the case where 3 is the destination exchange, the relay exchange 122 → 1
The route (fixed route 131) is described in the order of 23 → 124 → 113, and the transit exchanges 125 → 124 → 11
The route (fixed route 132) is described in the order of 3. That is, when the simple exchange 113 is the destination exchange, two fixed paths 131 and 132 are described. in this case,
One of the fixed routes is selected in a predetermined priority order.

[0011]

However, in a conventional switching system in which a plurality of relay route candidates are added to the call setting information to determine an automatic bypass route, a plurality of relay route candidates are added to the call setting information. However, if the call setup succeeds without trying all of the relay routes added to the call setting information, the candidate for the added and unexecuted relay route together with the call setting information forms a switching network including a relay exchange. Therefore, there is a problem that the communication capacity of the relay network is squeezed and the efficient communication of the relay network is hindered.

On the other hand, in the conventional switching system in which the route resolution exchanges hold the route information of the transit exchanges up to each of the terminating exchanges as fixed route information, the simple exchange itself determines whether or not to make a recall. Although it is possible, the route resolution exchange cannot know whether or not the simplified exchange will make a recall. For this reason, the route resolving switch, for example, attempts call setup using the first fixed route information having a higher priority from among the fixed route information, and even if the attempted call setup fails, the Route information is not retained.

That is, when the call setup fails, the route resolving switch does not hold the information on the fixed route that was tried. Therefore, when the simplified exchange makes a re-call, the route resolving exchange will again select and try the previous re-call using the fixed route based on the priority and try again until the fault is restored. Since calls cannot be made and re-calls are repeatedly made using the same fixed route, there is a problem that call setting loads on the transit exchanges on the same fixed route are concentrated, which hinders efficient use of the transit network. Was.

By the way, in such a repeated use of a fixed route with a fixed priority, a fixed route with a high priority is always selected, so that an available bandwidth on the fixed route with a high priority is reduced. For example, FIG.
In the switching system shown in FIG.
Although there are three fixed routes R1 to R3 among the fixed routes 51, if the priority is determined in the order of the fixed routes R1 → R2 → R3, the fixed route R1 having the higher priority is always selected and the call setup is performed. Is performed, the line connection using the fixed route R1 is performed one after another when the call setting is successful, and when the bandwidth used by the fixed route R1 is exceeded, the fixed route R2 having the next highest priority is selected. You.

As a result, for example, when a call setup requesting a large-capacity band is requested, a call setup request using the fixed route R1 is first tried each time, while the fixed route R1 becomes available. Since the bandwidth is reduced, there is also a problem that the blocking rate of calls that require this large-capacity bandwidth increases.

That is, in the switching system shown in FIG. 19, the priorities are set in the order of the fixed routes R1 → R2 → R3. As shown, the fixed route R1 → R2 →
In some cases, the available bandwidth of each route decreases in the order of R3, and the route selection for the fixed route having the small available bandwidth is repeated, and the improper priority order setting causes the above-described block rate to increase. There was a problem of becoming.

In order to solve such deterioration of the block rate, for example, using the path parameters such as the path cost value, the available bandwidth of the path, and the path block rate,
It is possible to change the priority of the fixed route. That is, it is possible to appropriately change the priority of the fixed route according to the network status of the switching network.

However, even when the priority of such a fixed route is appropriately changed according to the network condition of the switching network, for example, the first call request from the simplified exchange fails, and a re-call is made. If the priority of the fixed route is changed before the call is made, as described above, the route resolving switch does not store the call setting status of the fixed route that was tried, so the order of selection is changed, and When retrying a fixed route,
In some cases, the same fixed route is selected and repeated attempts are made.

For example, in FIG. 20, the cost value is used as a parameter to divide the period into four periods of "1" to "4".
If the first attempt fails using the fixed route R2 with the highest priority, the second attempt again fails using the fixed route R2 with the highest priority, and then, if a transition is made to the period “2” and a recall request is issued, the highest priority is given. Is selected and tried,
The fixed route R2 will be tried repeatedly. Therefore, even in such a case, there is a problem that the communication capacity for the switching network is squeezed and the block rate increases.

The present invention has been made in view of the above,
In a switching system in which a simple exchange is connected to a route resolution exchange that holds a fixed route, an automatic detour selection exchange that can reduce the communication load on the relay network and reliably receive a call without increasing the call setting block rate. It is an object to obtain a system and an automatic detour selection exchange method.

[0021]

To achieve the above object, an automatic detour selection switching system according to the present invention is connected to a switching network, and a plurality of fixed routes for each transit exchange in the switching network have a predetermined priority. A route resolution exchange that automatically selects a route to a destination indicated by a received call using the fixed route table, and a route resolution exchange that is directly connected to the route resolution exchange. A simple exchange that substitutes the route resolution exchange for the route selection for a call from a terminal connected to the simple exchange, wherein the simple exchange holds the number of re-calls. Means, setting means for setting a condition of whether or not to make a call again when receiving call release information due to call setting failure from the route resolution exchange; and The call setting information is sent to the route resolving exchange as simple call setting information, and when the call release information is received from the route resolving exchange due to call setting failure, the number of recalls held in the holding means is updated, Simple call control means for sending simple call setting information to which the updated number of re-calls is added to the route resolution exchange when the condition by the setting means is satisfied, wherein the route resolution exchange comprises:
A fixed route in the predetermined priority order corresponding to the number of re-calls indicated by the received simple call setting information is selected from the fixed route table, and a call destination indicated by the simple call setting information is selected based on the selected fixed route. And call control means for generating and sending relay call setting information to the communication device.

According to the present invention, the holding means on the side of the simplified exchange holds the number of re-calls, and the setting means determines whether or not to re-issue the call when it receives the call release information from the route resolution exchange due to call setting failure. Conditions are set. The simple call control means sends the call setting information to which the number of recalls has been added to the route resolving switch as the simple call setting information, and when receiving the call release information due to the call setting failure from the route resolving switch, the holding means And updates the simplified call setting information to which the updated number of times of recall is added to the route resolving switch when the condition by the setting means is satisfied. On the other hand, the call control means on the route resolution exchange side selects a fixed route in the predetermined priority order corresponding to the number of recalls indicated by the received simple call setting information from a fixed route table, and also determines the selected fixed route. At this time, the relay call setting information is created and transmitted to the called party indicated by the simple call setting information.

An automatic detour selection switching system according to the next invention has a fixed route table connected to a switching network and holding a plurality of fixed routes to each transit exchange in the switching network in a plurality of predetermined priorities. The fixed route table is used to determine one predetermined priority order from the plurality of predetermined priority orders in accordance with time, and based on the determined predetermined priority order, a destination indicated by an outgoing call. A route resolving exchange for automatically selecting a route to a call destination, and a simple exchange directly connected to the route resolving exchange and allowing the route resolving exchange to substitute a route for a call from a terminal connected to the simple exchange In the automatic detour selection switching system comprising: the simple exchange, holding means for holding at least a trial path number notified from the route resolution exchange, the route Setting means for setting a condition of whether or not a call is to be re-established when receiving call release information due to call setup failure from the decision exchange, and when receiving call release information due to call setup failure from the route resolution exchange, A simple call setting in which the holding means additionally holds the trial path number included in the call release information, and all trial path numbers including the additionally held trial path number are added when the condition by the setting means is satisfied. Simple call control means for sending information to the route resolution exchange, the route resolution exchange based on the predetermined priority order other fixed routes except the trial route number indicated by the received simple call setting information. A fixed route is selected from the fixed route table, and based on the selected fixed route, relay call setting information is created and transmitted to a destination indicated by the simple call setting information, and transmitted. If the call setup by the serial relay call setting information has failed, characterized in that and a call control means for notifying the trial fixed routing number of attempts to the simple exchange.

According to the present invention, the holding means on the simplified exchange side holds at least the trial path number notified from the path resolution exchange, and the setting means transmits the call release information from the path resolution exchange due to the failure of the call setting. A condition is set in advance as to whether or not a call will be re-received. The simple call control means, when receiving the call release information due to the failure of the call setting from the path resolution exchange, causes the holding means to additionally hold the trial path number included in the call release information, and to set the condition by the setting means. If satisfied, the simple call setup information to which all the trial path numbers including the additionally retained trial path numbers are added is sent to the path resolution exchange. On the other hand, the call control means on the route resolution exchange side selects a fixed route other than the trial route number indicated by the received simple call setting information from the fixed route table based on the predetermined priority order. Based on the selected fixed path, the relay call setting information is created and transmitted to the called party indicated by the simple call setting information, and if the call setting by the relay call setting information fails, the attempted The fixed path number is notified to the simplified exchange.

[0025] In the automatic detour selection switching system according to the next invention, in the above invention, the call control means of the route resolving switch is arranged so that the call setting based on the relay call setting information fails, If the fixed route selected from is the last fixed route, sends call release information including call rejection information indicating that all fixed routes have been tried to the simplified exchange, the setting means of the simplified exchange,
When the call rejection information is received, a condition for stopping the re-calling is set, and the simple call control means of the simple exchange receives the call release information including the call rejection information. In this case, the recall is stopped.

According to the present invention, the call control means of the route resolving switch sets the case where the call setting based on the relay call setting information fails and the fixed route selected from the fixed route table is the last fixed route. Sends call release information including call rejection information indicating that all fixed routes have been tried to the simplified exchange, and the setting means of the simplified exchange stops recalling when the call rejection information is received. The conditions are set, and the simple call control means of the simple exchange, when receiving the call release information including the call rejection information, stops the re-calling based on the conditions.

[0027] In the automatic detour selection switching method according to the next invention, the route resolving switch connected to the switching network holds a plurality of fixed routes for each transit switch in the switching network in a predetermined priority order. The fixed route table is used to automatically select a route to the destination indicated by the received call, and the simple exchange directly connected to the route resolution exchange is connected to the simple exchange. In the automatic detour selection and exchange method in which the route selection exchange for the call from the terminal is substituted by the route resolution exchange, the simple exchange provides the route resolution exchange with information added with an initial value of the number of recalls. A simple call setting step of transmitting simple call setting information, which is information requesting a proxy for selection, and selecting a fixed route having a predetermined priority based on the simple call setting information, A relay call setting step of transmitting relay call setting information having a fixed route to a called party; and, if the call setting by the relay call setting step fails, call release information indicating that the relay call setting has failed. A notification step of notifying the simplified exchange, and, when receiving notification of call release information indicating that the call setup based on the relay call setup information has failed from the route resolution exchange, re-establishing a call based on predetermined conditions. A recalling determination step for determining whether or not to perform the recalling, and when the recalling is performed in the recalling determination step, the current number of recalls is updated, and the simplified call setting information to which the updated number of recalls is added is retransmitted. Re-simple call setting step, and selecting a fixed route in the predetermined priority order corresponding to the number of recalls added to the simple call setting retransmitted in the re-simple call setting step from the fixed route table. Fixed Characterized in that it comprises a re-relay call setting step of sending by creating a relay call setting information road against incoming call destination indicated by the simple call setup information based, the.

According to the present invention, first, in the simple call setting step, the information is the information to which the simple exchange has added the initial value of the number of recalls to the route resolution exchange, and is the information for requesting the proxy for the route selection. The simple call setting information is transmitted, and in the relay call setting step, the route resolving switch selects a fixed route having a predetermined priority based on the simple call setting information, and selects the fixed call having the selected fixed route. The setting information is sent to the called party, and the notification step causes the route resolution exchange to, when the call setting in the relay call setting step fails, the call release information indicating that the relay call setting has failed Notifying the simplified exchange, and when the simplified exchange receives the notification of the call release information indicating that the call setup based on the relay call setup information has failed from the route resolution exchange in the recalling determination step, Conditions and determines whether to perform the original in recalling the, by the re simple call setup process, simple switchboard,
When a re-call is performed by the re-call determination step, the current number of re-calls is updated, and the simplified call setting information with the updated number of re-calls added is re-transmitted. The fixed route of the predetermined priority order corresponding to the number of recalls added to the simple call setting retransmitted by the re-simple call setting step is selected from the fixed route table, and the fixed route is selected based on the selected fixed route. The relay call setting information is created and transmitted to the destination indicated by the simple call setting information.

[0029] In the automatic detour selection switching method according to the next invention, the route resolving switch connected to the switching network holds a plurality of fixed routes to each transit switch in the switching network in a plurality of predetermined priorities. Having a route table, using the fixed route table, determine one predetermined priority order from the plurality of predetermined priority order corresponding to time, based on the determined predetermined priority order, The route to the destination indicated by the call is automatically selected, and the simple exchange directly connected to the route resolution exchange selects a route for a call from a terminal connected to the simple exchange to the route resolution exchange. A simple call setting step of sending simple call setting information for requesting a proxy for route selection from the simple exchange to the route resolution exchange; A relay call setting step of selecting a fixed path having a predetermined priority based on the setting information and transmitting the relay call setting information having the selected fixed path to a called party; A notification step of notifying the simplified exchange of call release information added with the failed trial fixed path number when the relay call setting has failed; and a predetermined condition when the notification of the call release information is received. A re-call determination step for determining whether or not to make a re-call, and adding the trial fixed path number notified this time to the trial fixed path number currently held when re-calling is performed in the re-call determination step. A simple call setting step of holding and retransmitting the simplified call setting information to which all the trial path numbers including the additionally fixed trial fixed path number are added to the route resolution exchange; and a retransmission by the simple call setting step. Done simple From the fixed path except the trial route number added to the call setting, select a fixed path of the predetermined priority order from the fixed path table,
A re-relay call setting step of creating and sending relay call setting information to a called party indicated by the simple call setting information based on the selected fixed path.

According to the present invention, first, in the simple call setting step, the simple exchange sends the simple call setting information requesting the proxy for the route selection to the route resolving exchange. The solution switch selects a fixed route having a predetermined priority based on the simple call setting information, sends the relay call setting information having the selected fixed route to a called party, and, by a notification step, When the relay call setting in the relay call setting step fails, the path resolution exchange notifies the simplified exchange of call release information to which the failed trial fixed path number is added, and the simplified call When the exchange receives the notification of the call release information, the exchange determines whether or not to perform a re-call based on a predetermined condition.
In the case where a re-call is performed by the re-calling determination step, the trial fixed path number notified this time is additionally held to the trial fixed path number currently held, and all trial path numbers including the additionally retained trial fixed path number Re-transmit the simplified call setup information to the route resolving switch, and in the re-relay call setting step, the route resolving switch sets the trial path number added to the re-transmitted simple call setting in the re-simple call setting step. From among the fixed routes to be excluded, a fixed route in the predetermined priority order is selected from the fixed route table, and based on the selected fixed route, the relay call setting information is transmitted to the destination indicated by the simple call setting information. Is created and sent.

[0031] In the automatic detour selection and exchange method according to the next invention, in the above invention, the notifying step is performed when the relay call setting in the relay call setting step has failed, and the fixed path selected from the fixed path table is selected. When the route is the last fixed route, the call release information including call rejection information indicating that all fixed routes have been tried is sent to the simplified exchange, and the re-calling determination step includes the call rejection information. When receiving the call release information including the call release information, the recalling is stopped.

According to the present invention, in the notification step, the route resolving switch sets the case where the relay call setting in the relay call setting step has failed and the fixed path selected from the fixed path table is the last fixed path. Then, call release information including call rejection information indicating that all fixed routes have been tried is sent to the simplified exchange, and the simplified exchange transmits call rejection information indicating that all fixed routes cannot be used to the terminal. Including the call release information, and in the recall determination step, the
When the call release information including the call rejection information is received, the recalling is stopped, and the terminal receiving the call release information including the call rejection information from the simplified exchange recognizes that the call processing has failed. ing.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an automatic detour selection and exchange system and an automatic detour selection and exchange method according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 First, a first embodiment of the present invention will be described. FIG. 1 is a diagram showing an entire configuration of an automatic detour selection and exchange system according to a first embodiment of the present invention. In FIG. 1, in this automatic detour selection switching system, the transit exchanges 41 to 49 and the route resolution exchange 3
1 and 32, and has a route resolution exchange 31,
32 directly connects the simplified exchanges 11 to 13 and 21 to 23, respectively.

The route resolution exchange 31 is further connected to transit exchanges 41, 44 and 47, and the route resolution exchange 32 is
Connected to transit exchanges 43, 46, 49. The transit exchange 42 connects the transit exchanges 41, 43, 45, the transit exchange 45 connects the transit exchanges 42, 44, 46, 48, and the transit exchange 48 connects the transit exchanges 45, 47, 49. In addition, the simple exchanges 11 to 13, 21 to 23
Connects one or more terminals (not shown).

Each of the route resolution exchanges 31 and 32 has a fixed route table holding fixed route information. For example, the route resolution exchange 31 has a fixed route table 50. The fixed route table 50 holds fixed route numbers and fixed routes including designated transit exchanges corresponding to the respective fixed route numbers. In the fixed route table 50, for example, a part of a fixed route from the route resolution exchange 31 to the simplified exchange 21 is shown, and here, three fixed route numbers “1” to “3” are used.
The fixed paths corresponding to “3” are shown.

In the fixed route number "1", the designated transit exchanges 41 → 42 → 43 → 32 (route resolution exchange 32) → 21
The route information of the fixed route of the (simple exchange 21) is shown, and the fixed route number “2” is assigned to the designated transit exchange 44 → 45 → 4.
6 → 32 (route resolution exchange 32) → 21 (simple exchange 2
The route information of the fixed route of 1) is shown, and the fixed route number “3” indicates the designated relay exchange 47 → 48 → 49 → 32.
The route information of the fixed route from (route solution exchange 32) to 21 (simple exchange 21) is shown. In this case, the values of the fixed route numbers “1” to “3” correspond to the priorities when the fixed route is selected, but the relationship between each fixed route number and the priority is arbitrarily changed. be able to. For example, the priorities can be set in the order of the fixed path number “2” → “3” → “1”, and the priorities can be changed and set as time elapses thereafter.

When the simplified exchange 11 receives a call setting request for terminating the simplified exchange 21 from a terminal (not shown) connected to the simplified exchange 11, the simplified exchange setting is performed to the route solution exchange 31 directly connected. Information 51 is transmitted, and the route setting exchange 31 substitutes the call setting via the relay network.
The simple call setting information 51 includes an information element indicating that the request is a call setting request, a calling address indicating the address “11” of the simple exchange 11 that is the caller, and a simple exchange 2 that is the call destination.
1; a destination address indicating the address “21”; a call management number;
It includes traffic contract information such as a band, route selection cost information such as the number of hops, and the number of recalls, which is a feature of this embodiment.

Upon receiving a call setup request including simple call setup information 51 from the directly connected simple exchange 11, the route resolution exchange 31 has a fixed route of a priority order corresponding to the value of the number of recalls in the simple call setup information 51. Is automatically selected, and a call setup for the selected fixed route is attempted. In this case, a fixed route having a fixed route number having the same value as the value of the number of recalls is selected. The call setting for this transit network is performed sequentially between the transit exchanges. For example, when the fixed route corresponding to the fixed route number “1” having the highest priority is selected, the transit exchange 42 , 43, the relay exchange 42 switches to the relay exchange 41.
, And the transit exchange 42 releases the call to the route resolution exchange 31.

The route resolution exchange 31 receiving the call release
Determines that the trial of the fixed route corresponding to the fixed route number “1” has failed, and
In the case where the simplified exchange 11 makes a recall, on the other hand, an update is performed by adding “1” to the number of recalls, and the recall that includes the call setting information 51 having the recall number of the updated value is performed. A request is made to the route resolution exchange 31.

The route resolving switch 3 which has received the recall request
1 is a fixed route number corresponding to the updated number of re-calls,
That is, the fixed route corresponding to the fixed route number “2” having the next priority is selected. Then, the route resolution switch 31 attempts to set up a call for the selected fixed route. As a result, the route resolution exchange 31 does not select the same fixed route even when a recall request is issued from the simplified exchange 11.

FIG. 2 is a block diagram showing a detailed configuration of the simplified exchange 11. As shown in FIG.
Has a call control unit 71. The call control unit 71 receives a call setting request from a terminal (not shown), makes a call setting request to the directly connected route resolution exchange 31, and Delegate the selection of a relay route to the relay network.

Further, if there is a call setting request for a terminal (not shown) to which the simplified exchange 11 is connected, the route setting exchange 31 sets up a call for this terminal. In other words,
The simple exchange 11 does not give any route information of the relay route up to the incoming call, and can perform the call setup only by sending out the other call setup information other than the relay route to the route resolution exchange 31. In a sense, it is a "simple exchange".

The simplified exchange 11 includes a recall selection setting unit 73.
And the call control unit 71
a. The recall selection setting unit 73 sets a condition of whether or not to perform a recall when the outgoing call request or the recall request is unsuccessful. It is determined whether or not to make a recall according to the set conditions.

It should be noted that the call control unit 71
Receiving the call release 52 from No. 1 recognizes that the call request or the recall request has failed. The condition set by the recall selection setting unit 73 is, for example, on condition that the number of recalls reaches a predetermined value, and the call control unit 71 stops the recall when the number of recalls reaches the predetermined value, or After the elapse of a predetermined time, control is performed to make a call again. This predetermined value is desirably, for example, the number of relay routes held by the route resolution exchange 31.

The simple exchange 11 further includes a simple exchange 71
Has a number-of-recalls table 72 for storing the number of re-calls for each terminal (not shown) connected thereto. When a call is made for the first time with the initial value set to “0” as the value of the number of recalls table 72, a call request for setting the number of recalls to “0” is sent to the route resolving switch 31. Further, the value of the number of recalls stored in the recall number table 72 is updated by adding “1” every time a recall is performed, as described above, and the call control unit 7 is updated.
At the time of a recall, 1 adds the updated number of recalls to the simplified call setting information 51 and makes a recall request to the route resolution exchange 31.

FIG. 3 is a block diagram showing a detailed configuration of the route resolution exchange 31. In FIG. 3, the route resolution exchange 31 has a call control unit 81. When the call control unit 81 receives a call request or a recall request from the simple exchange 11, the fixed route selected by the route selection unit 81a. In order to attempt a call setup for
A call request is made to one of the 47.

The above-mentioned fixed route table 50 is connected to the call control unit 81, and the route selection unit 81 in the call control unit 81.
a performs selection processing for extracting a fixed path number corresponding to the value of the number of recalls in the accepted call request or recall request from the fixed path table 50. In this case, since the fixed route number corresponds to the priority and the number of recalls as described above, the fixed route for which the call setup has failed is not retried.

Referring now to the flowchart shown in FIG. 4, a description will be given of the procedure of a call setting process between the simplified exchange 11 and the route resolution exchange 31. In FIG. 4, first, the simplified exchange 11 determines whether there is a call setting request from a terminal (not shown) to be connected (step S101). If there is a call setting request from the terminal (step S101, YES), the recall count table 72
From this, the number of re-calls corresponding to the terminal that made the call request is obtained, and the number of re-calls is added to the call setting information. Is set (step S102). Thereafter, a call request is made by sending the call setting information to which the number of recalls has been added to the route solution exchange 31 directly connected (step S103).

On the other hand, the route resolution exchange 31 determines whether or not there is a call setting request from the simplified exchange 11 (step S121), and receives the call setting request (step S12).
In the case of (1, YES), a fixed path corresponding to the number of recalls and the called party included in the call setting information is selected from the fixed path table 50 (step S122). Further, the route resolving switch 31 tries to set up a call to the relay network using the selected fixed route (step S12).
3).

Thereafter, the route resolving switch 31 determines whether or not the call setup of the fixed route attempted in step S123 has failed based on whether or not the call release from the relay network has been received (step S124). If not failed (step S124, NO), a call setting completion notification is sent to the simplified exchange 11 (step S125), and the process proceeds to step S121, where the call setting has failed (step S124).
124, YES), a notification of the call release 52 including the call rejection information is sent to the simplified exchange 11 (step S126), and the process proceeds to step S121. Note that the call rejection information in this case is the content of a state where the call setup for the relay network has failed, for example, information such as failure information and the reason for the call setup failure.

On the other hand, the simplified exchange 11 receives the notification of the call setting completion or the notification of the call release 52 from the route resolving exchange 31 to determine whether the call setting has failed (step S104). That is, call release 52
Is received, the simplified exchange 1 determines that the call setting has failed. Call setting is not failed (step S1)
04, NO), a call setting completion notification is sent to the terminal that made the call request (step S105), and the subsequent connection processing is performed, and the process proceeds to step S101. On the other hand, the call setup failed (step S104, YE
In the case of S), it is determined whether or not to make a recall again based on the condition preset by the recall selection setting unit 73 (step S106).

No recall is made (step S106, N
O) In other words, if the recall is to be stopped, the terminal is notified of a call rejection, that is, a call release is notified (step S107), and the process for the call request is terminated. Transition. On the other hand, when a recall is performed (step S106, YES), the value of the number of recalls in the recall number table 72 is incremented and updated (step S108), and the process proceeds to step S103. That is, the renewal call request to which the call setting information to which the updated number of recalls is added is added to the route resolving switch 3.
1 and the above process is repeated.

According to the first embodiment, even when the route solving exchanges 31 and 32 carry out route selection while holding fixed routes having fixed priorities, the simple exchanges 11 to 11 can be used.
13, 21 to 23 only store the number of recalls, so that a different fixed route can be selected each time a recall is made, so that the fixed route for which call setup has failed is not repeated and tried again, and the relay network Even if a failure occurs, the system can automatically bypass the relay path with a simple configuration and make a reliable incoming call promptly, and the inefficiency associated with a call request to the relay network The communication load does not increase.

Embodiment 2 Next, a second embodiment of the present invention will be described. In the first embodiment described above,
Depending on the condition set by the recalling selection setting unit 73 and the number of fixed routes, particularly when the number of fixed routes is small and the upper limit value of the number of recalls set as a condition is high, the fixed value at the time of recalling to the relay network is fixed. Although the route may be repeated, the second embodiment effectively prevents the fixed route from being selected a plurality of times.

FIG. 5 is a diagram showing the entire configuration of the automatic detour selection and exchange system according to the second embodiment of the present invention. The configuration of the automatic detour selection switching system shown in FIG. 5 is different from the automatic detour selection switching system shown in FIG. 1 in that the route resolution exchanges 31 and 32 respond to call setting requests from the simple exchanges 11 to 13 and 21 to 23. In the case where the call setting for all the fixed routes held in the fixed route table 50 is unsuccessful, a configuration is provided in the call rejection information of the call release to notify that it is the last call setting process. The configuration is the same as the configuration of the automatic detour selection switching system shown in FIG.

That is, the route resolving exchange 31 responds to the re-call request from the simple exchange 11 by using the fixed route table 5
If the call setup is attempted using all the different fixed routes within 0 and the call setup fails, the call route rejection information within the call release 52 indicates that the fixed route selected this time is the “last” fixed route. Is added to the information on the fixed route selection indicating that the information has been sent.

FIG. 6 is a block diagram showing a detailed configuration of the simplified exchange 11 shown in FIG. In FIG. 6, the recalling selection setting unit 73 sets, as the condition of the recalling, to stop the recalling when the information of the fixed route selection from the route resolving exchange 31 is “last”. Further, the re-calling determination unit 71a of the call control unit 71
It is determined whether or not the call is to be re-established based on the condition (3). The other configuration is the same as the configuration shown in FIG.

FIG. 7 is a diagram showing a route resolution exchange 31 shown in FIG.
FIG. 3 is a block diagram showing a detailed configuration of the embodiment. 7, the call control unit 81 further includes a final determination unit 81b, and the other configuration is the same as that of the route resolution exchange 31 shown in FIG. The final determination unit 81b determines whether the fixed route stored in the fixed route table 50 is the last fixed route. When the call setting of the fixed route determined by the final determination unit 81b to be the last fixed route fails, the call control unit 81
"Last" is added to the call rejection information of the call release 52 as fixed route selection information and transmitted to the simplified exchange 11.

Referring now to the flowchart shown in FIG. 8, a description will be given of a call setting processing procedure between the simplified exchange 11 and the route resolution exchange 31 according to the second embodiment. In FIG. 8, first, the simple exchange 11
Determines whether there is a call setting request from a connected terminal (not shown) (step S201). If there is a call setting request from the terminal (step S201, YES), the number of recalls corresponding to the terminal that made the call request is obtained from the number of recalls table 72, and the number of recalls is referred to as call setting information. In this case, since this is the first call setting, the value of the number of recalls is set to the initial value “0” (step S202). Thereafter, the call setting information to which the number of recalls has been added is transmitted to the route resolution exchange 3 directly connected.
(Step S).
203).

On the other hand, the route resolving switch 31 determines whether or not there is a call setting request from the simplified switch 11 (step S221), and receives the call setting request (step S22).
In the case of (1, YES), a fixed route corresponding to the number of recalls and the called party included in the call setting information is selected from the fixed route table 50 (step S222). Further, the route resolving switch 31 tries to set up a call to the relay network using the selected fixed route (step S22).
3).

Thereafter, the route resolving switch 31 determines whether or not the call setup of the fixed route attempted in step S223 has failed based on whether or not the call release from the relay network has been received (step S224). If not failed (step S224, NO), a call setting completion notification is sent to the simplified exchange 11 (step S225), and the process proceeds to step S221. On the other hand, if the call setup has failed (step S224, YES), it is further determined whether the fixed route selected this time is the last fixed route (step S226).

The last fixed route (step S22)
In the case of (6, YES), the fixed route selection information indicating that the fixed route is the last is added to the call rejection information of the call release 52 (step S227), and the process proceeds to step S228. It is not the last fixed route (step S226, N
In the case of O), the process directly proceeds to step S228, and a notification of the call release 52 including the call rejection information is sent to the simplified exchange 11 (step S228), and step S221 is performed.
Move to

On the other hand, the simplified exchange 11 determines whether or not the call setup has failed by receiving the notification of the call setup completion or the notification of the call release 52 from the route resolution exchange 31 (step S204). That is, call release 52
Is received, the simplified exchange 1 determines that the call setting has failed. Call setting is not failed (step S2)
04, NO), a call setting completion notification is sent to the terminal that made the call request (step S205), and the subsequent connection processing is performed, and the process proceeds to step S201. On the other hand, the call setup failed (step S204, YE
In the case of S), it is determined whether or not to make a recall again based on the conditions set in advance by the recall selection setting unit 73 (step S206).

No recall is made (step S206, N
O) In other words, if the recall is to be stopped, the terminal is notified of the call rejection, that is, the call release is notified (step S207), and the process for the call request is terminated. Transition. On the other hand, if the call is to be re-established (step S206, YES), it is further determined whether or not "last" is added as fixed route selection information (step S208).

"Last" (step S208, YE
S) In this case, the call request is stopped, and the terminal
A call rejection notification including that the call setting for all the paths has failed is performed (step S209), and the process shifts to step S201 to wait for the next call request from the terminal. on the other hand,
If it is not “last” (step S208, NO),
The value of the number of re-calls in the re-call number table 72 is incremented and updated (step S209), and step S20 is performed.
Move to 3. That is, a recall request to which the call setting information to which the updated number of recalls is added is made to the route resolving switch 31, and the above-described processing is repeated.

In the second embodiment, when the fixed route selection information is "last", the call control unit 71 stops the re-calling. It means a re-call and not a re-call from the terminal. The re-calling of the terminal is a re-calling performed by the terminal when the notification of the call rejection including the information that the call setting for all the routes has failed is received from the simplified exchange 11. When this terminal is re-called, the simplified exchange 11 sets the number of re-calls to "0" and repeats the above-described processing.

According to the second embodiment, the first embodiment
In addition to the operation and effect of the above, when the route resolution exchanges 31 and 32 try to set up the call for all the fixed routes and fail, the simple exchanges 11 to 13 and 21 to 23 select a fixed route. Is notified that the last is the last. Therefore, the simplified exchanges 11 to 13 and 21 to 23 use this notification to ensure that the call setting is not retried for the fixed path in which the call setting has failed. can do.

Embodiment 3 Next, a third embodiment of the present invention will be described. In Embodiments 1 and 2 described above, the simple exchange adds the number of recalls to the call setting information and makes a call setting request to the route resolution exchange. The resolved exchange notifies the simplified exchange of the fixed route that was attempted, and when the simplified exchange re-calls, notifies the route-resolved exchange of the notified route that has been notified, so that the route-resolved exchange has priority over the fixed route selection. Even when the order is changed over time, a fixed route that has been tried once is not selected.

FIG. 9 is a diagram showing the entire configuration of the automatic detour selection and exchange system according to the third embodiment of the present invention. The configuration of the automatic detour selection switching system shown in FIG. 9 is different from the automatic detour selection switching system shown in FIG. 5 in that the route solving exchanges 31 and 32 and the simple exchanges 11 to 13, 21 to 23
Only the configuration is different, and the other configurations are the same.

The route resolution exchange 31 has a fixed route table 60 in which the designated relay exchanges indicating the fixed routes corresponding to the five fixed route numbers “1” to “5” are connected in the order of connection. It is remembered. Further, in the fixed route table 60, a value obtained by weighting the priority order for selecting a fixed route by a parameter, here, a total cost value weighted using a cost value is stored as a reference for selecting each fixed route. A plurality of the total cost values are provided, and a total number of the total cost values corresponding to the time zone of the use time are stored. For example, in the fixed route table 60, three total cost values “(1)” to “(3)” are provided, and each total cost value is applied when the corresponding time zone is reached.

For example, the fixed route corresponding to the fixed route number “1” is the designated transit exchange 41 → 42 → 43 → 32
(Route switching exchange 32) → 21 (simple exchange 21), but the total cost value has three values depending on the time zone. That is, the values of the total cost values “(1)” to “(3)” are “19”, “22”,
It has a different value of "38". Other fixed routes also have a total cost value that changes according to the time zone.

For example, the total cost value “(1)” of the fixed route corresponding to the fixed route number “4” is “22” and the total cost value “(2)” is “19”.
In the time period corresponding to the total cost value “(1)”, the fixed route corresponding to the fixed route number “1” has the smallest total cost value. Since the priority of the route selection is the highest and the total cost value of the fixed route corresponding to the fixed route number “4” is the smallest value in the time zone corresponding to the total cost value “(2)”, the fixed route The fixed route with the number “4” has the highest priority of the fixed route selection. In this way,
Change the priority of fixed route selection sequentially for each time zone,
The most suitable route can be selected in that time zone.

When a call request or a recall request is made, the simplified exchange 11 generates call setting information 61 to which the number of recalls and, if there is a route that has already been recalled, a tried route number, are added, and The solution is sent to the exchange 31. The attempted route number is notified from the route resolving switch 31 when an attempt to set up a call to the relay network corresponding to the call request or the recall request fails.

Upon receiving a call request or a re-call request from the simplified exchange 11, the route resolution exchange 31 selects a fixed route from the fixed routes excluding the fixed route indicated by the tried route number notified from the simplified exchange 11. The fixed route having the smallest total cost value corresponding to the time zone at the time, that is, the fixed route having the highest priority is selected, and an attempt is made to set up a call to the relay network. Thereafter, when the call setup fails, the route resolution switch 31 notifies the call release 62 as shown in FIG.

That is, the route resolving switch 31 notifies the simplified switch 11 of the call release 62 including the call rejection information added with the current trial route number for which the call setup has failed and the number of untried fixed routes. In this case, the simplified exchange 11 knows that all fixed routes have been tried, as in the case of “last” in the second embodiment, by setting the value of the number of unfixed fixed routes to “0”. Can be.

FIG. 10 is a block diagram showing a detailed configuration of the simplified exchange 11 shown in FIG. In FIG. 10, the recalling selection setting unit 73 sets, as a condition of the recalling, to stop the recalling when the value of the number of unfixed fixed routes notified from the route resolving switch 31 is “0”. are doing. Further, the re-calling determination section 71a of the call control section 71 determines whether or not to make a re-call based on the condition of the re-call selection setting section 73.

Further, the simplified exchange 11 has a trial path number table 74 corresponding to the number-of-recalls table 72. As in the second embodiment, the trial path number table 74 stores the number of recalls for each terminal, and additionally stores the current trial path number notified from the path resolution exchange 31 every time a call is released. . And the simple exchange 11
Retrieves all the trial path numbers stored in the trial path number table 74 when performing a recall, and adds it as a tried path number to the call setting information of the recall request.

FIG. 11 shows the route resolution exchange 3 shown in FIG.
FIG. 2 is a block diagram showing a detailed configuration of the first embodiment. In FIG. 11, the call control unit 81 has an optimum route selection unit 81c and an untried fixed route number calculation unit 81d. Optimal route selection unit 81
c is the total cost corresponding to the current time zone from among the fixed routes excluding the fixed route indicated by the tried route number notified from the simplified exchange 11 when the fixed route stored in the fixed route table 60 is selected. Select the fixed route with the smallest value.

When the call setup fails, the selected fixed route is used as the above-described trial route number for call release 6
2 is added. In addition, the number of untested fixed routes calculation unit 81d
Subtracts the number of fixed paths selected by the optimum path selection unit 81c from the number of all fixed paths. This subtracted value is added to the call release 62 as the above-mentioned number of unfixed fixed routes when the call setup fails.

Referring now to the flowchart shown in FIG. 12, a description will be given of a call setting processing procedure between the simplified exchange 11 and the route resolution exchange 31 according to the third embodiment. In FIG. 12, first, the simple exchange 1
1 judges whether there is a call setting request from a terminal (not shown) to be connected (step S301). If there is a call setting request from the terminal (step S301, YES), the number of recalls corresponding to the terminal that made the call request is acquired from the trial path number table 74, and the number of recalls is referred to as call setting information. In this case, since this is the first call setting, the value of the number of times of recall is set to the initial value “0” (step S302). Thereafter, a call request is made by sending the call setting information to which the number of recalls has been added to the route solution exchange 31 directly connected (step S303).

On the other hand, the route resolution exchange 31 determines whether or not there is a call setting request from the simplified exchange 11 (step S321), and receives the call setting request (step S32).
In the case of (1, YES), based on the number of re-calls and the tried route number included in the call setting information, the current time zone is selected from among the fixed routes excluding the tried route. The fixed route having the smallest total cost value is selected from the fixed route table 60 (step S322). Further, the route resolving switch 31 tries to set up a call to the relay network using the selected fixed route (step S32).
3).

Thereafter, the route resolving exchange 31 judges whether the call setup of the fixed route attempted in step S323 has failed based on whether a call release from the relay network has been received (step S324). If not failed (step S324, NO), a call setting completion notification is sent to the simplified exchange 11 (step S325), and the process proceeds to step S321. On the other hand, if the call setting has failed (step S324, YES), the call rejection information including the fixed path number of the fixed path selected this time and the number of untried fixed paths calculated by the untried fixed path number calculation unit 81d. Is notified to the simplified exchange 11 (step S326), and the process proceeds to step S321.

On the other hand, the simplified exchange 11 judges whether or not the call establishment has failed by receiving the notification of the completion of the call establishment or the notice of the call release 62 from the route resolution exchange 31 (step S304). That is, call release 62
Is received, the simplified exchange 1 determines that the call setting has failed. Call setting is not failed (step S3
04, NO), a call setting completion notification is sent to the terminal that made the call request (step S305), and the subsequent connection processing is performed, and the process proceeds to step S301. On the other hand, the call setup failed (step S304, YE
In the case of S), it is determined whether or not to perform a re-call based on the condition preset by the re-call selection setting unit 73 (step S306).

No recall is made (step S306, N
O) In other words, if the recall is to be stopped, the terminal is notified of the rejection of the call, that is, the call is released (step S307), and the process for the call request is terminated. Transition. On the other hand, if the call is to be re-established (step S306, YES), it is further determined whether or not the number of unfixed fixed routes is “0” (step S308). "0" (step S30)
In the case of (8, YES), the call request is stopped, and a notification of the call rejection including the fact that the call setting for all the paths has failed is sent to the terminal (step S309), and the process proceeds to step S301. Waits for the next call request from the terminal.

On the other hand, it is not "0" (step S308,
In the case of NO), the value of the number of recalls in the trial path number table 74 is incremented and updated, and the notified current trial path number is additionally stored in the trial path number. Then, call setting information to which all the previous trial path numbers including the current trial path number are added is generated (step S310), and the process proceeds to step S303. That is, a recall request having the call setting information to which the updated number of recalls and all the trial path numbers are added is made to the route resolving switch 31, and the above processing is repeated.

In the third embodiment, when the value of the number of unfixed fixed routes is "0", the call control unit 71 stops the re-calling. 11 means no re-call from the terminal. The re-calling of the terminal is a re-calling performed by the terminal side when receiving a call rejection notification including a message that the call setting for all the routes has failed from the simplified exchange 11. When this terminal is re-called, the simplified exchange 11 sets the number of re-calls to "0" and repeats the above-described processing.

According to the third embodiment, the fixed routes tried by the route solving exchanges 31 and 32 are replaced by the simplified exchanges 11 to 1.
3, 21 to 23, and the simplified exchanges 11 to 13, 2
When a call is made to a re-established call, the fixed route notified is added to the call setting information for the re-call and the route-resolved exchange 3
1 and 32, it is possible to reliably identify the already selected fixed route even when the route resolution exchanges 31 and 32 select the fixed route under different conditions for each time zone. Therefore, it is possible to eliminate the situation that the already selected fixed route is selected again and tried again, and the route solving exchanges 31 and 32 notify the simplified exchanges 11 to 13 and 21 to 23 of the number of untried fixed routes. , The simple exchanges 11 to 13, 21
23 can know that trials have been performed for all fixed routes when the number of unfixed fixed routes is “0”,
Useless call setting for the relay network can be reduced, and reduction in the communication capacity of the relay network can be prevented.

[0089]

As described above, according to the present invention, in the simplified exchange, the holding means holds the number of recalls, and the setting means receives the call release information due to the failure of the call setting from the route resolution exchange. In this case, a condition is set to determine whether or not the call will be reissued. The simple call control means sends the call setting information to which the number of recalls has been added to the route resolving switch as the simple call setting information, and when receiving the call release information due to the call setting failure from the route resolving switch, the holding means And updates the simplified call setting information to which the updated number of times of recall is added to the route resolving switch when the condition by the setting means is satisfied. On the other hand, the call control means on the route resolution exchange side selects a fixed route in the predetermined priority order corresponding to the number of recalls indicated by the received simple call setting information from a fixed route table, and also determines the selected fixed route. Since the relay call setting information is created and transmitted to the called party indicated by the simple call setting information,
The selection of different fixed routes according to the number of recalls can be reliably performed with a simple configuration to reduce the call blocking rate, and the call state corresponding to the selection of the fixed route managed by the route resolution switch can be changed to a simple switch. Since the management is performed on the side, there is an effect that the load on the route resolution exchange is reduced.

According to the next invention, in the simplified exchange, the holding means holds at least the trial path number notified from the route resolution exchange, and the setting means transmits the call release information due to the failure of the call setting from the route resolution exchange. A condition is set in advance as to whether or not to receive a call again. The simple call control means, when receiving the call release information due to the failure of the call setting from the path resolution exchange, causes the holding means to additionally hold the trial path number included in the call release information, and to set the condition by the setting means. If satisfied, the simple call setup information to which all the trial path numbers including the additionally retained trial path numbers are added is sent to the path resolution exchange. On the other hand, the call control means on the route resolution exchange side selects a fixed route other than the trial route number indicated by the received simple call setting information from the fixed route table based on the predetermined priority order. Based on the selected fixed path, the relay call setting information is created and transmitted to the called party indicated by the simple call setting information, and if the call setting by the relay call setting information fails, the attempted Since the fixed path number is reported to the simplified exchange, useless call setting trials are stopped, and the effect of reducing the communication load on the switching network is achieved.

According to the next invention, the call control means of the route resolving switch sets the case where the call setting based on the relay call setting information has failed and the fixed route selected from the fixed route table is the last fixed route. Then, call release information including call rejection information indicating that all fixed paths have been tried is sent to the simplified exchange, and the setting means of the simplified exchange stops re-calling when the call rejection information is received. Since a condition to be set is set in advance and the simple call control means of the simple exchange receives the call release information including the call rejection information, the simple call control means stops the re-call based on the condition. Even if the priority of the fixed route is changed depending on the time zone, it is possible to reliably prevent the retry of the fixed route once attempted, and to perform the efficient call setup trial, Call setup Since the reduced an effect that load on the relay network is also reduced.

According to the next invention, first, in the simple call setting step, the simple exchange switches to the route resolution exchange.
The simplified call setting information, which is information to which the initial value of the number of recalls is added and which is information requesting a proxy for route selection, is transmitted. A fixed route having a predetermined priority is selected, and relay call setting information having the selected fixed route is transmitted to a called party. In the case where the call setup fails, the simple exchange notifies the simple exchange of call release information indicating that the relay call setup has failed. When the notification of the call release information indicating that the call setup by has failed has been received, it is determined whether or not to perform a re-call based on predetermined conditions. Recall decision When a re-call is performed depending on the re-call, the current number of re-calls is updated, and the simplified call setting information with the updated number of re-calls added is re-transmitted. Selecting a fixed route of the predetermined priority order corresponding to the number of recalls added to the simple call setting retransmitted in the setting step from the fixed route table, and selecting the simple call setting information based on the selected fixed route. The relay call setting information is created and transmitted to the called party indicated by (1), so that a different fixed path can be reliably selected according to the number of recalls, and the call blocking rate can be reduced. In addition, since the call state corresponding to the selection of the fixed route managed by the route resolution exchange is managed by the simple exchange, the effect of reducing the load on the route resolution exchange is reduced. To.

According to the next invention, first, in the simple call setting step, the simple exchange switches the route resolution exchange to the
The simple call setting information for requesting the proxy for the route selection is transmitted, and the route resolving switch selects a fixed route having a predetermined priority based on the simple call setting information by a relay call setting step, and performs the selection. The relay call setting information having the fixed route is sent to the called party, and if the route resolution switch fails in the relay call setting in the relay call setting step by the notification step, the failed trial fixed path Notifying the simplified exchange of the number-added call release information to the simplified exchange, and in the recall decision step, when the simplified exchange receives the notification of the call release information, performs a recall based on a predetermined condition. In the re-simple call setting step, the simplified exchange adds the trial fixed path number currently notified to the trial fixed path number currently held when re-calling is performed in the re-call determination step. And retransmits the simplified call setting information to which all the trial path numbers including the additionally retained trial fixed path number are added to the route resolving switch. From the fixed paths except for the trial path number added to the simplified call setting retransmitted in the call setting step, a fixed path having the predetermined priority order is selected from the fixed path table, and based on the selected fixed path, Since the relay call setting information is created and transmitted to the called party indicated by the simple call setting information, the useless call setting attempt is stopped to reduce the communication load on the switching network. It has the effect of being able to do so.

According to the next invention, in the notification step,
When the relay call setting in the relay call setting step has failed and the fixed route selected from the fixed route table is the last fixed route, the route resolving exchange issues a signal indicating that all fixed routes have been tried. Sending out call release information including call rejection information to the simplified exchange, the simplified exchange sends out call release information including call rejection information indicating that all fixed paths cannot be used to the terminal; If the simple exchange receives the call release information including the call rejection information, the simple exchange stops the reissue call, and the terminal receiving the call release information including the call rejection information from the simple exchange fails in the call processing. Even if the priority of the fixed route is changed depending on the time zone, it is possible to reliably prevent the fixed route from being retried once, and to efficiently perform the call setup trial. Do this It is, so useless call setup is reduced there is an effect that load on the relay network is also reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an automatic detour selection and exchange system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of the simplified exchange shown in FIG.

FIG. 3 is a block diagram showing a detailed configuration of the route resolution exchange shown in FIG.

FIG. 4 is a flowchart showing a call setting processing procedure between the simple exchange and the route resolution exchange of the automatic detour selection exchange system according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an entire configuration of an automatic detour selection and exchange system according to a second embodiment of the present invention;

FIG. 6 is a block diagram showing a detailed configuration of the simplified exchange shown in FIG.

FIG. 7 is a block diagram showing a detailed configuration of the route resolution exchange shown in FIG.

FIG. 8 is a flowchart showing a call setting processing procedure between a simple exchange and a route resolution exchange of the automatic detour selection exchange system according to the second embodiment of the present invention.

FIG. 9 is a diagram showing an entire configuration of an automatic detour selection and exchange system according to a third embodiment of the present invention;

FIG. 10 is a block diagram showing a detailed configuration of the simplified exchange shown in FIG.

FIG. 11 is a block diagram showing a detailed configuration of the route resolution exchange shown in FIG.

FIG. 12 is a flowchart showing a call setting processing procedure between a simple exchange and a route resolution exchange of the automatic detour selection exchange system according to the third embodiment of the present invention.

FIG. 13 is a block diagram showing a schematic configuration of a conventional switching system that automatically calculates an automatic detour route.

FIG. 14 is a diagram showing a configuration of a conventional switching system that determines an automatic detour route by adding a plurality of relay route candidates in call setting information.

FIG. 15 is a diagram showing an example of the content of call setting information to which a plurality of relay route candidates are added.

FIG. 16 shows a case where the route resolution exchange holds fixed route information,
FIG. 9 is a diagram illustrating a configuration of a conventional switching system that determines an automatic detour route using the fixed route information.

FIG. 17 is a diagram showing an example of the content of fixed route information held by the route resolution exchange.

FIG. 18 is a diagram illustrating an example of inappropriate fixed route selection when fixed route information is used.

FIG. 19 is a diagram showing an example of inappropriate fixed route selection when fixed route information is used.

FIG. 20 is a diagram showing an example of parameters held by a conventional switching system that changes priorities at the time of fixed route selection for each time zone.

[Explanation of symbols]

11-13, 21-23 Simple exchange, 31, 32 Route resolution exchange, 41-49 Transit exchange, 50, 60
Fixed route table, 51, 61 call setting information, 52, 6
2 Call release, 71, 81 Call control unit, 71a Recall decision unit, 72 Recall count table, 73 Recall selection setting unit, 74 Trial route number table, 81a Route selection unit, 81b Final decision unit, 81c Optimal route selection Part, 8
1d Non-trial fixed route calculation unit.

Continued on the front page F term (reference) 5K026 AA17 AA19 EE10 GG03 HH06 LL06 5K051 AA01 DD01 EE01 FF04 FF17 FF18 GG01 HH16 5K065 AA03 CA01 DA23 DA42 DA53 DA56 EA06 EA15

Claims (6)

[Claims] 1. A fixed route table, which is connected to a switching network and holds a plurality of fixed routes to each transit exchange in the switching network in a predetermined priority order. A route resolution exchange for automatically selecting a route to a destination indicated by a call; and a route resolution exchange for directly connecting to the route resolution exchange and selecting a route for a call from a terminal connected to the simple exchange. In the automatic detour selection switching system including a simple exchange to be substituted, the simple exchange includes a holding unit for holding the number of re-calls, and a re-establishment when receiving a call release information due to a call setting failure from the route resolution exchange. Setting means for setting a condition as to whether or not to make a call; sending call setting information to which the number of recalls has been added as simple call setting information to the route resolution exchange; A simple call setting that updates the number of recalls held in the holding means when receiving call release information due to a call setting failure from the server, and adds the updated number of recalls when the condition by the setting means is satisfied. Simple call control means for transmitting information to the route resolution exchange, wherein the route resolution exchange changes the fixed route in the predetermined priority order corresponding to the number of recalls indicated by the received simple call setting information to the fixed route. Call control means for selecting from a table, creating and transmitting relay call setting information to a called party indicated by the simple call setting information based on the selected fixed path, and Automatic detour selection and exchange system. 2. A fixed route table which is connected to a switching network and holds a plurality of fixed routes for each transit exchange in the switching network in a plurality of predetermined priorities. One predetermined priority order is determined from the plurality of predetermined priority orders in association with each other, and a route to the destination indicated by the call is automatically selected based on the determined predetermined priority order. Automatic detour selection and exchange system, comprising: a route resolution exchange to be performed; and a simple exchange directly connected to the route resolution exchange and allowing the route resolution exchange to proxy the route selection for a call from a terminal connected to the simple exchange. In the simple exchange, holding means for holding at least a trial path number notified from the route resolution exchange, and call release information due to call setup failure from the route resolution exchange Setting means for setting a condition as to whether or not a call is to be re-established when received, and holding the trial path number included in the call release information when receiving call release information from the path resolution exchange due to a call setting failure. Means for additionally storing the simple call setting information to which all of the trial path numbers including the trial path number additionally held are added to the route resolution exchange when the condition by the setting means is satisfied. Means for selecting a fixed path other than the trial path number indicated by the received simple call setting information from the fixed path table based on the predetermined priority order. Based on the selected fixed path, the relay call setting information is created and transmitted to the destination indicated by the simple call setting information, and the call setting based on the relay call setting information fails. And a call control means for notifying the simplified exchange of the trial fixed path number that has been tried. 3. The call control means of the route resolving switch, when the call setting based on the relay call setting information fails and the fixed route selected from the fixed route table is the last fixed route, Call release information including call rejection information indicating that all fixed routes have been tried is sent to the simplified exchange, and the setting means of the simplified exchange stops recalling when the call rejection information is received. A condition is set, and the simple call control means of the simple exchange, when receiving the call release information including the call rejection information, stops the re-call based on the condition. 3. The automatic detour selection and exchange system according to 1 or 2. 4. A route resolution switch connected to a switching network,
A fixed route table for holding a plurality of fixed routes for each transit exchange in the switching network in a predetermined priority order, and using the fixed route table to automatically route the route to the destination indicated by the received call; An automatic detour selection and exchange method in which a simple exchange directly connected to the route resolution exchange directly connects the route resolution exchange to a call from a terminal connected to the simple route exchange. A simple call setting step of transmitting simple call setting information, which is information to which an initial value of the number of recalls is added and which is information requesting a proxy for path selection, from the exchange to the route resolution exchange; A relay call setting step of selecting a fixed path having a predetermined priority based on the information, and transmitting relay call setting information having the selected fixed path to a called party; A notification step of notifying the simplified exchange of call release information indicating that the relay call setting has failed when the call setting by the switch has failed; and a notification that the call setting by the relay call setting information from the route resolution switch has failed. A re-call determination step of determining whether or not to perform a re-call based on predetermined conditions when the notification of the call release information is received, and a current re-call when the re-call is performed by the re-call determination step. A re-simple call setting step of updating the number of calls and re-transmitting the simplified call setting information with the updated re-number of calls added; and a re-number of call added to the simplified call setting re-transmitted in the re-simulated call setting step. Selecting a fixed route of the predetermined priority order corresponding to the fixed route table from the fixed route table, and creating relay call setting information for a call destination indicated by the simple call setting information based on the selected fixed route. During sending Automatic Alternate selection exchange method characterized by comprising a call setting step. 5. A route resolution switch connected to a switching network,
A fixed route table for holding a plurality of fixed routes for each transit exchange in the switching network with a plurality of predetermined priorities; using the fixed route table, the plurality of fixed priorities of the plurality of predetermined priorities corresponding to time; One of the predetermined priorities is determined, a route to the destination indicated by the call is automatically selected based on the determined predetermined priority, and the route is directly connected to the route resolution exchange. An automatic detour selection switching method in which a simplified exchange causes the route resolving exchange to substitute a route for a call from a terminal connected to the simplified exchange. A simple call setting step of sending simple call setting information requesting a fixed call path having a predetermined priority based on the simple call setting information, and a relay call setting having the selected fixed path. A relay call setting step of transmitting information to a called party; and when the relay call setting in the relay call setting step fails, notifies the simplified exchange of call release information to which the failed trial fixed path number is added. A re-calling step of determining whether to perform a re-call based on a predetermined condition when the notification of the call release information is received; and performing a re-call by the re-call determination step. In this case, the simple call setting information obtained by additionally holding the trial fixed path number notified this time to the currently held trial fixed path number and adding all the trial path numbers including the additionally held trial fixed path number to the route A re-simple call setting step for re-sending to the solution exchange; and, from among fixed paths excluding the trial path number added to the re-simulated call setting re-transmitted in the re-simple call setting step, the fixed path in the predetermined priority order is selected. Previous A re-relay call setting step of selecting from a fixed path table and creating and sending relay call setting information to a called party indicated by the simple call setting information based on the selected fixed path. Characteristic automatic detour selection exchange method. 6. The method according to claim 1, wherein the notifying step is performed when the relay call setting in the relay call setting step has failed, and when the fixed path selected from the fixed path table is the last fixed path, all the fixed paths are set. Call release information including call rejection information indicating that the retrying call has been attempted, and the recalling determination step stops the recalling when the call release information including the call rejection information is received. 6. The automatic detour selection and exchange method according to claim 4, wherein: