JP2011250330A - Communication method and communication system, which provide relay connection service - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication method and a communication system which can prevent an increase in message size in the case of relay connection using an IP network.SOLUTION: In a relay connection provider network making information relay connection by using an IP network among communication networks (PSTN) of a plurality of common carriers, a communication method comprises a relay determination DB device 2 which includes a relay determination DB 200 storing information mapped to incoming number information for determining whether a call is to be relayed or an incoming call to a terminal 6 within the own IP network (own IP network incoming call). When a PSTN-GW 1a receives an incoming call request signal from a common carrier A, the relay determination DB device 2 is inquired of whether the call is for relay connection or an own IP network incoming call. In the case of the own IP network incoming call, the incoming call request signal is transmitted to the terminal 6 through a relay server 3, a subscriber server 4, and an IP conversion device 5 without applying encapsulation processing.

Description

  The present invention relates to a communication method and a communication system for providing a relay connection service in an IP (Internet Protocol) network.

  A telecommunications carrier that provides a conventional public switched telephone network (PSTN) service using a call control protocol ISUP (ISDN user part) includes a relay connection operator that provides a relay connection service. This relay connection service means, for example, that a relay connection provider interconnects two regional fixed-line carriers, and calls control signals, voice signals, etc. during communication between these two regional fixed-line carriers Is a relay connection service. In order for one carrier to secure communications with other carriers, it is necessary to prepare an interconnection line with each carrier. Utilizing a carrier's relay connection service makes it possible to communicate with other communication carriers connected to the relay connection carrier simply by preparing an interconnection line with the relay connection carrier, thereby reducing equipment costs. There is a merit that can be done.

  A specific process of the relay connection service in the conventional PSTN will be described. FIG. 6 is an explanatory diagram of a configuration of a communication system that provides a relay connection service in a conventional PSTN and a flow of relay connection processing.

  As shown in FIG. 6, communication networks (PSTNs) of other communication carriers A, B, and C are connected to a communication carrier network that provides a relay connection service (hereinafter referred to as “relay connection carrier network”). Has been. The relay connection carrier network includes an IGS (gateway switch) 7 (7a, 7b), an IC (relay switch) 8, a GC (subscriber switch) 9, and a terminal 6 of the relay connection carrier. When the relay connection provider performs only the relay connection service and does not perform the regional fixed communication service, it is not necessary to provide the GC 9 and the terminal 6. It is common to provide services together. Therefore, description will be made assuming that the GC 9 and the terminal 6 are included in the relay connection carrier network.

  The following three patterns are conceivable when information transmitted from the communication network (PSTN) of the communication carrier A is relay-connected to the communication network (PSTN) of another communication carrier.

(Pattern 1) When the communication network of the communication carrier A is relay-connected to the communication network of the communication carrier B connected to the IGS 7b via the IGS 7a and IC8. Here, IGS7 that receives a signal from the transmission side and transmits it to the reception side is referred to as IGS7a, and IGS7 that receives a signal via IC8 and transmits it to the reception side is referred to as IGS7b.
(Pattern 2) A case where the communication network of the communication carrier A is relay-connected to the communication network of the communication carrier C having the same connection point as the IGS 7a.
(Pattern 3) When a call is received from the communication network of the communication carrier A to the terminal 6 of the subscriber accommodated in the relay connection carrier network.

  A specific processing procedure for the patterns 1 to 3 will be described.

  First, in all cases of patterns 1 to 3, the IGS 7a receives a signal from the communication network of the communication carrier A.

  Next, the IGS 7a determines the connection destination from the called number information (called number or called number band) of the received signal, and executes the process by dividing it into the aforementioned three patterns.

(Pattern 1)
If the connection destination is a connection to a communication network of another communication carrier having a connection point to IGS 7 different from IGS 7a, a signal is transmitted to the corresponding IGS 7 (for example, IGS 7b). IGS7b transfers a signal to the communication network of the communication carrier B which has a connection point in own IGS7b based on the called number information attached | subjected to the received signal.
At this time, the IGS 7a and the IGS 7b perform transparent relay of information except for some information that must be set or changed when the relay connection provider relays signals. Here, “transparent relay” refers to relaying without rewriting the signal contents, and the relay connection carrier, in principle, uses information set by the calling carrier and the receiving carrier. Transparent transmission is defined as a technical standard (see Non-Patent Document 1). Note that the information that the relay connection carrier must set when relaying the signal is information indicating which relay connection carrier later required as billing information passed through the call, etc. The information that must be performed is a parameter or the like indicating the capability and characteristics of the line connecting the communication carriers. Except for some of these pieces of information, relay connection providers must relay information transparently.

(Pattern 2)
If the connection destination is a connection to a communication network of another communication carrier (communication carrier C) having a connection point to the IGS 7a as in the case of the IGS 7a that has received the signal, the IGS 7a sends the signal to the corresponding communication carrier C. To the other communication network. At this time, the IGS 7a performs transparent relay of information except for some information that must be set or changed when the relay connection provider relays signals.

(Pattern 3)
If the connection destination is a connection to the terminal 6 of the subscriber in the relay connection operator network, a signal is transmitted to the IC 8 of the own relay connection operator network, and the signal is transmitted to the terminal 6 via the GC 9.

Information and Communication Technology Committee, “TTC Standard JJ-90.10 (Interconnect Common Interface Specification)” Version 7.1, established on September 5, 2006, p.20

  In recent years, IP telephone technology has become widespread in place of conventional PSTN technology. In the case of the PSTN circuit switching system, since one line is occupied for each call, facilities (lines) that can withstand the peak call volume are required between the switches. Therefore, a corresponding equipment cost is required, and the use efficiency of the equipment (line) is not high. On the other hand, in the case of an IP network, since call control signal packets, voice packets, etc. for a plurality of calls share the IP network, the equipment cost can be reduced for the communication carrier, and the user fee can be reduced accordingly. There is a merit.

  However, when an IP network is introduced for relay connection, the following problems arise. The interconnection between PSTN and IP network is described in "TTC standard JF-IETF-RFC3398 (Technical specifications related to SIP-TTC ISUP signaling system interconnection)" (Information and Communication Technology Committee, Version 1.0, June 2, 2005) However, the connection form is limited to the interconnection between PSTN (ISUP) -IP (SIP: Session Initiation Protocol) networks, for example, PSTN-IP network-PSTN. Such a form that provides a relay connection service over an IP network is not included in the scope ("TTC standard JF-IETF-RFC3398" p.9).

When interconnecting an IP network and a PSTN, it is necessary on the IP network side to convert the received ISUP signal into a SIP signal or convert the SIP signal into an ISUP signal for transmission. In this relay via ISUP->SIP-> ISUP, if ISUP-> SIP conversion is performed according to the current standard, etc., some ISUP parameters are lost, so when the converted SIP signal is further converted into an ISUP signal The ISUP parameter set by the caller is not transmitted transparently to the callee. For example, when an “address” message (IAM: Initial address message) indicating a connection request for a communication line in the ISUP protocol is converted into a session start request (INVITE) of the SIP protocol, “User Service Information” is an optional parameter of the IAM. The mapping of (Q.931 “Transmission capability” information element) ”is not specified in the TTC standard JF-IETF-RFC3398. Therefore, there are cases where transparent relay is not possible.
As described above, in the technical standard for relay connection in PSTN, it is stipulated that, in principle, information is relayed transparently (see Non-Patent Document 1). Similarly, in the case of relay connection in an IP network, However, it is required to perform transparent relay.

  As a countermeasure against this, SIP has a technique called ISUP encapsulation in which the entire ISUP signal is included and transferred as binary data in the SIP signal. By using this technique, transparent relay can be realized (IETF RFC3398). See chapter 5.1, ITU-T Q.1912.5, chapter 5.4 ISUP encapsulation-detailed procedures). However, the ISUP encapsulation method is effective when the destination is the PSTN and the ISUP signal is used. For example, when the terminal in the IP network of the relay connection operator is the destination (relay connection operator) Since the encapsulated ISUP signal is not necessary, a SIP signal with unnecessary information contained therein and an increased message size is transmitted (see pattern 3 in FIG. 2 described later). ). Since an increase in message size imposes a load on the IP network, it is necessary to perform efficient information transmission that prevents an increase in message size.

  In view of such a background, the present invention has been made, and the present invention provides a communication method and a communication system capable of preventing an increase in message size when relay connection is performed using an IP network. Let it be an issue.

  In order to solve the above-described problem, the invention according to claim 1 is configured to transfer an incoming call request signal received from a communication network of a communication carrier serving as a transmission source to a communication network of another communication carrier serving as a transmission destination. A gateway device on the originating side that receives a signal transmitted from the PSTN of the communication carrier that is the transmission source to the IP network of the relay connection carrier that performs the relay connection, and the incoming call request signal that is the destination Whether the call is a relay connection to a communication network of a telecommunications carrier or a call received at a terminal accommodated in a subscriber server in the IP network of the relay connection carrier is attached to the incoming call request signal. A relay determination DB device that stores a relay determination DB for each received called number information, and is used in a communication system that provides a relay connection service, wherein the originating gateway device includes the transmission source Communication by the operator Receiving the incoming call request signal from the mobile station, and transmitting relay determination request information including the incoming call number information attached to the incoming call request signal to the relay determination DB apparatus. The call determination signal is referred to the relay determination DB using the called number information of the information as a key, and the call request signal is a call that is relay-connected to the communication network of another communication carrier as the transmission destination, or the relay It is determined whether the call is an incoming call in the IP network of the connection operator, and the determination result is transmitted to the gateway device on the calling side, and the gateway device on the calling side determines that the incoming call request signal is the relay connection. When a determination result indicating that the call is an incoming call in the IP network of the operator is received, the incoming call request signal is converted into an incoming call request IP signal used in the IP network, and a subscriber of the IP network is converted. Server, and the destination Via the IP conversion apparatus connected to a end, to the terminal, and a communication method and transmits the IP signal of the called request.

  The invention according to claim 6 is a relay connection operator that relay-connects an incoming call request signal received from a communication network of a communication carrier that is a transmission source to a communication network of another communication carrier that is a transmission destination. And a call-side gateway device that receives a signal transmitted from the PSTN of the communication carrier that is the transmission source, and the communication network of the other communication carrier that is the transmission destination. Whether the call is relay-connected to the terminal or whether the call is received at a terminal accommodated in a subscriber server in the IP network of the relay-connecting carrier for each called number information attached to the incoming call request signal. A relay judgment DB device for storing a relay judgment DB, and providing a relay connection service, wherein the originating gateway device receives the incoming call from a communication network of a communication carrier as a transmission source. A reception control unit for receiving a request signal; A DB access unit that transmits relay determination request information including the called number information attached to the received incoming call request signal to the relay determination DB device, and the incoming call request signal is transmitted from the relay determination DB device to the relay determination DB device. A protocol conversion unit that converts the incoming call request signal into an incoming call request IP signal used in the IP network when receiving a determination result that the call is an incoming call in the IP network of the connection operator; A first routing unit that transmits an IP signal of the incoming call request to the terminal via an IP network subscriber server and an IP conversion device connected to the terminal that is a destination; The relay determination DB device refers to the relay determination DB using the relay determination DB and the called party number information of the relay determination request information received from the originating gateway device as a key, and Is a call that is relay-connected to the communication network of the other carrier serving as the transmission destination, or an incoming call within the IP network of the relay-connection carrier, and the determination result is And a relay determination processing unit that transmits to the originating gateway device.

  In this way, the originating gateway device receives the determination result that the incoming call request signal is an incoming call in the IP network of the relay connection carrier from the relay determination DB, so that the PSTN arrival is received. It is possible to transmit the IP signal of the incoming call request after the protocol conversion to the terminal in the IP network without performing the encapsulation process of the call request signal. Therefore, according to the present invention, it is possible to perform relay connection that eliminates the need for unnecessary encapsulation and prevents an increase in message size.

  The invention according to claim 2 further includes a destination gateway device connected to the PSTN of another communication carrier serving as the transmission destination in the IP network of the relay connection carrier, and the originating gateway device Is received from the relay determination DB device when the determination result that the call request signal is a call to be relay-connected to a communication network of another communication carrier serving as the transmission destination is received. Protocol conversion of the signal into an incoming call request IP signal used in the IP network, encapsulating the incoming call request signal in the incoming call request IP signal, and sending the incoming call request signal to the incoming gateway apparatus; When the gateway apparatus on the side receives the IP signal of the incoming call request signal in which the incoming call request signal is encapsulated, the encapsulated incoming call request signal is decapsulated and used in the PSTN. Call Into a demand signal, the incoming call request signal, and a communication method according to claim 1, characterized by transmitting to the destination to become another carrier's communication network.

  The invention according to claim 7 further includes a destination gateway device connected to the PSTN of another communication carrier serving as the transmission destination in the IP network of the relay connection carrier, When the gateway apparatus receives a determination result from the relay determination DB apparatus that the incoming call request signal is a call to be relay-connected to a communication network of another communication carrier as the transmission destination, the protocol conversion An encapsulation processing unit that encapsulates the incoming call request signal in an IP signal of the incoming call request that is converted by the unit into the protocol, and wherein the first routing unit encapsulates the incoming call request signal When the incoming call request IP signal is transmitted to the incoming gateway device, and the incoming gateway device receives the incoming call request IP signal in which the incoming call request signal is encapsulated, Decapsulation of the pselled incoming call request signal to be converted into an incoming call request signal used in the PSTN, and an incoming call request used in the PSTN converted by the decapsulation part The communication system according to claim 6, further comprising: a second routing unit that transmits a signal to a communication network of another communication carrier serving as the transmission destination.

  In this way, the originating gateway device receives a determination result from the relay determination DB that the incoming call request signal is a call that is relay-connected to the communication network of another communication carrier that is the transmission destination. As a result, the IP signal of the incoming call request in which the incoming call request signal is encapsulated is transmitted to the gateway device on the called side. Then, the gateway device on the called side releases the encapsulation of the encapsulated incoming call request signal, converts it to an incoming call request signal used in PSTN, and transmits it to another communication carrier as a transmission destination. Can do. Therefore, it becomes possible to realize a transparent relay connection.

  According to a third aspect of the present invention, the calling gateway device is a call in which the incoming call request signal is relay-connected from the relay determination DB device to a communication network of another communication carrier serving as the transmission destination. When receiving the determination result that there is, when the communication network of the other communication carrier as the transmission destination is connected to the gateway device on the calling side, the incoming call request signal is transmitted to the transmission destination. The communication method according to claim 2, wherein the communication method is transferred to a communication network of another communication carrier.

  By doing in this way, the gateway device on the calling side has received a determination result from the relay determination DB that the incoming call request signal is a call that is relay-connected to the communication network of another communication carrier that is the transmission destination. In this case, if a communication network of another communication carrier as a transmission destination is connected to the originating gateway device, protocol conversion for converting the incoming call request signal into an incoming call request IP signal used in the IP network The incoming call request signal can be transferred to the communication network of another communication carrier that is the transmission destination without performing the process and the encapsulation process of the incoming call request signal of the PSTN.

  According to a fourth aspect of the present invention, the calling side gateway device is a call in which the incoming call request signal is relay-connected from the relay determination DB device to a communication network of another communication carrier as the transmission destination. When the determination result is received, the incoming call request signal is stored in the storage unit of the gateway device on the calling side, and the communication of the communication carrier serving as the transmission source is stored. When a call control signal transmitted in response to the incoming call request signal from the network is received, the storage unit confirms that the incoming call request signal is stored as the call for relay connection, and the call The control signal is protocol-converted into a call control IP signal used in the IP network, the call control signal is encapsulated in the call control IP signal, and transmitted to the destination gateway device. The gateway device is When the call control signal encapsulated in the call control signal is received, the encapsulated call control signal is decapsulated and converted into a call control signal used in the PSTN, and the call control signal The communication method according to claim 2, wherein the communication method is transmitted to a communication network of another communication carrier serving as the transmission destination.

  In this way, by storing that the incoming call request signal is a relay connection call in the storage unit of the originating gateway device, the incoming call request signal is transmitted from the communication carrier's communication network as the transmission source. When the call control signal transmitted in response is received, it is possible to eliminate the need for the gateway device on the calling side to transmit the relay determination request information to the relay determination DB device and receive the response signal again.

  According to a fifth aspect of the present invention, when the destination gateway apparatus receives the IP signal of the incoming call request encapsulating the incoming call request signal from the gateway apparatus of the outgoing side, the incoming call request The signal is a call that is relay-connected to the communication network of another communication carrier that is the transmission destination, and is stored in the storage unit of the gateway device on the called side, and the communication of the other communication carrier that is the transmission destination When a call control signal transmitted in response to the incoming call request signal is received from the network, the storage unit confirms that the incoming call request signal is stored as the call for relay connection, and The control signal is protocol-converted into a call control IP signal used in the IP network, the call control signal is encapsulated in the call control IP signal, and transmitted to the originating gateway device. Gateway device When the call control IP signal encapsulated in the call control signal is received, the encapsulated call control signal is decapsulated and converted into a call control signal used in the PSTN, and the call The communication method according to claim 4, wherein a control signal is transmitted to a communication network of a communication carrier that is the transmission source.

  In this way, by storing in the storage unit of the destination gateway device that the incoming call request signal is a relay connection call, an incoming call request is received from the communication network of another communication carrier serving as a transmission destination. When the call control signal transmitted in response to the signal is received, it is possible to eliminate the need for the gateway device on the called side to transmit the relay determination request information again to the relay determination DB device and receive the response signal.

  According to the present invention, it is possible to provide a communication method and a communication system capable of preventing an increase in message size when relay connection is performed using an IP network.

It is a figure which shows the structure of the communication system which provides the relay connection service which concerns on this embodiment. It is a figure for demonstrating the connection pattern of the relay connection which concerns on this embodiment. In the communication system according to the present embodiment, when the communication network A (PSTN) of the communication carrier A is relay-connected to the communication network (PSTN) of the communication carrier B via the relay connection operator network (IP network) ( It is a sequence diagram explaining the flow of processing of pattern 1). In the communication system according to the present embodiment, when the communication network (PSTN) of the communication carrier A is relay-connected to the communication network (PSTN) of another communication carrier C having a connection point to the same PSTN-GW (pattern) It is a sequence diagram explaining the flow of processing of 2). In the communication system which concerns on this embodiment, it is a sequence diagram explaining the flow of a process when it arrives at the terminal of the subscriber accommodated in a relay connection provider network (pattern 3). It is explanatory drawing of the structure of the communication system which provides the relay connection service in the conventional PSTN, and the flow of the process of relay connection.

  Next, modes for carrying out the present invention (referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate.

<< System configuration >>
FIG. 1 is a diagram illustrating a configuration of a communication system that provides a relay connection service according to the present embodiment. As shown in FIG. 1, this communication system is a relay that performs relay connection of signals between communication networks of communication carriers A, B, and C and communication networks of the communication carriers A, B, and C. Consists of a connected carrier network. Here, it is assumed that the communication networks of the communication carriers A, B, and C are PSTN (ISUP), and the relay connection carrier network is an IP network (SIP).

  The relay connection provider network (IP network) includes a PSTN-GW (gateway device) 1 (1a, 1b) that serves as a gateway relay server to the PSTN, a relay determination DB (DataBase) device 2, and a relay server 3. And the subscriber server 4 and the IP conversion device 5 that accommodates the terminal 6. In addition, when the relay connection provider performs only the relay connection service and does not perform the regional fixed communication service, it is not necessary to include the subscriber server 4, the IP conversion device 5, and the terminal 6, but the relay connection provider In the IP network as well, it is common to provide a local fixed communication service together as in the prior art. Accordingly, the description will be made assuming that the subscriber server 4, the IP conversion device 5, and the terminal 6 are included in the relay connection carrier network.

  The PSTN-GW 1, the relay determination DB device 2, the relay server 3, and the subscriber server 4 are realized by a computer including an input / output unit, a processing unit, and a storage unit (all not shown). The input / output unit includes an input / output interface. The processing unit is realized by a program execution process by a CPU (Central Processing Unit) included in each server, a dedicated circuit, or the like. The storage unit is realized by a storage unit such as a RAM (Random Access Memory), a hard disk, or a flash memory. When these devices (servers) are realized by program processing, the storage unit stores a program for realizing the functions of the devices (servers).

  The terminal 6 is a telephone terminal having a metal line interface, and transmits a dial number, a voice signal, and the like. The IP conversion device 5 is a device that accommodates a terminal 6 using a metal line and converts a call control signal or a voice signal from the terminal 6 into a signal used on the IP network. The IP conversion device 5 may be installed in a station or set in a user's home. Hereinafter, each device provided in the IP network will be described in detail.

(Subscriber server)
The subscriber server 4 manages the service contract information of the subscribers accommodated by the subscriber server 4 itself and manages the call state, and receives a call signal from the terminal 6 via the IP converter 5 and Call control is performed in which a transmission destination is determined and a call signal and a response signal received from the relay server 3 or the like in the own network are routed to the terminal 6.

(Relay server)
The relay server 3 is connected to the PSTN-GW 1 (1a, 1b), the subscriber server 4, and the like, and relays call control signals such as routing call signals and response signals received from other devices.

(PSTN-GW)
The PSTN-GW (gateway device) 1 is a gateway gateway device to the communication networks (PSTN) of other communication carriers A, B, C, and the PSTN from the communication networks of other communication carriers A, B, C. The signal is converted into an IP signal in its own network and transmitted, or conversely, the IP signal in its own network is converted into a PSTN signal used in the communication networks of other carriers A, B, and C and transmitted. Or Here, PSTN-GW1 that receives a signal from the originating side and transmits it to the terminating side is PSTN-GW1a (originating gateway device), and receives the signal via relay server 3 and further transmits it to the terminating side. -Let GW1 be PSTN-GW1b (destination gateway device).
The PSTN-GW1 includes a reception control unit 11 (11a, 11b), a DB access unit 12 (12a, 12b), and an encapsulation target call storage control unit 13 (13a), respectively, in the PSTN-GW1a and the PSTN-GW1b. 13b), protocol conversion unit 14 (14a, 14b), encapsulation processing unit 15 (15a, 15b), decapsulation unit 16 (16a, 16b), and routing unit 17 (17a, 17b). Prepare.

  When receiving the incoming call request signal (ISUP-IAM signal) from the communication network (PSTN) of another carrier, the reception control unit 11 outputs the received incoming call request signal to the DB access unit 12 described later. To do. Further, when receiving the incoming call request signal (SIP-INVITE) from the relay server 3, the reception control unit 11 outputs the received incoming call request signal to the encapsulation target call storage control unit 13 described later. The reception control unit 11 receives a call control signal transmitted in response to the incoming call request signal, that is, a call control signal other than IAM (ISUP signal) or a call control signal other than INVITE (SIP signal). Even when the call request signal is received as a response signal or the like, it is output to the encapsulation target call storage control unit 13 in order to determine whether or not the call is a relay connection call as will be described later.

  When the DB (database) access unit 12 acquires the incoming request signal (ISUP-IAM signal) from the reception control unit 11, relay determination including the called number information attached to the acquired incoming request signal (ISUP-IAM signal). Request information is generated, and the relay determination request information is transmitted to the relay determination DB device 2 to determine whether the call is a relay connection or an incoming call to the terminal 6 in the local IP network (hereinafter referred to as “local IP network reception”). Request judgment information.

When the encapsulation target call storage control unit 13 is the encapsulation target call storage control unit 13a of the originating PSTN-GW1 (PSTN-GW1a), the incoming call request signal (ISUP) When the fact that the -IAM signal is a relay connection is received, the fact that the call (incoming request signal) is a relay connection call is stored in the storage unit (not shown) of the PSTN-GW 1a.
Further, when the encapsulation target call storage control unit 13 is the encapsulation target call storage control unit 13b of the incoming PSTN-GW1 (PSTN-GW1b), when the reception control unit 11 receives the SIP INVITE message, It is determined whether the encapsulated ISUP message information is stored in the SIP message. If the ISUP message information is stored, it is determined that the received call (incoming request signal) is a relay connection call. It memorize | stores in the memory | storage part (not shown) of GW1b.

Further, when the encapsulation target call storage control unit 13 receives a call control signal (ISUP) transmitted in response to an incoming call request signal, the outgoing call signal (incoming call request signal) is transmitted to its own PSTN-GW1. It is confirmed whether or not it is stored in the storage unit as a relay connection call. The encapsulation target call storage control unit 13 outputs the call control signal (ISUP) to the protocol conversion unit 14 and the encapsulation processing unit 15 when stored as a relay connection call.
By doing so, when the PSTN-GW 1 receives the call control signal (ISUP) transmitted in response to the incoming request signal, the DB access unit 12 again sends the call to the relay determination DB device 2. It is possible to eliminate the need to make an inquiry as to whether the (incoming request signal) is a relay connection or an incoming IP network.

  The protocol conversion unit 14 mutually converts a protocol (for example, ISUP) used in the PSTN and a protocol (for example, SIP) used in the IP network.

  The encapsulation processing unit 15 encapsulates the received ISUP message information in the SIP message. For the encapsulation of the ISUP message information, for example, the above-described ISUP encapsulation method is used.

  The decapsulation unit 16 extracts the ISUP message information encapsulated in the SIP message, decapsulates it, and converts it to ISUP.

  The routing unit 17 performs processing for routing the signal based on the called number information (called number or called number band) attached to the received signal.

(Relay determination DB device)
Based on the request from the PSTN-GW 1 (relay determination request information), the relay determination DB device 2 determines whether the incoming call request signal is a signal to be relay-connected or a signal to be received by the terminal 6 in its own IP network (local IP). Is determined based on the relay determination DB 200 described later, and the result is transmitted as response information to the PSTN-GW 1 that has transmitted the relay determination request information. The relay determination DB device 2 includes a relay determination processing unit 20 and a relay determination DB 200.

  The relay determination DB 200 stores whether the signal is a relay connection or an incoming IP network in association with the called number information (called number or called number band). Further, when the target called number is a relay connection, the destination PSTN-GW1 (for example, “PSTN-GW (a)” (PSTN-GW1a), etc.) is shown in association with the called number information. Additional information may be stored. In addition, when the target called number is an incoming call to the own IP network, additional information indicating the IP address of the subscriber server 4 that accommodates the destination terminal 6 in association with the called number information is stored. Also good.

  When the relay determination processing unit 20 receives the relay determination request information from the PSTN-GW 1, the relay determination processing unit 20 refers to the relay determination DB 200 using the called number information of the incoming call request signal attached to the relay determination request information as a key, and receives the incoming call request. It is determined whether the signal is a relay connection or an incoming IP network, and information on the determination result is attached to the response information and returned to the PSTN-GW 1 that has transmitted the relay determination request information. Here, for example, the determination result may return a bit of “1” in the case of relay connection and “0” in the case of an incoming call of the own IP network. Further, the relay determination processing unit 20 may attach additional information such as the relay destination PSTN-GW1 to the response information and transmit it to the PSTN-GW1 that has transmitted the relay determination request information.

  The relay determination DB 200 and the relay determination processing unit 20 may be provided in each PSTN-GW1.

≪Processing procedure≫
Next, the processing procedure of the relay connection service according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram for explaining a connection pattern of relay connection according to the present embodiment. As shown in FIG. 2, when information transmitted from the communication network (PSTN) of the communication carrier A is relay-connected to the communication network of another communication carrier via the relay connection operator network (IP network). There are the following three patterns. Note that the communication network of the communication carrier A and the communication carrier C is connected to the PSTN-GW 1a, and the communication network of the communication carrier B is connected to the PSTN-GW 1b.

(Pattern 1)
When the communication network of the communication carrier A is relay-connected to the communication network of the communication carrier B connected to the PSTN-GW 1b via the PSTN-GW 1a and the relay server 3.
(Pattern 2)
A case where the communication network of the communication carrier A is relay-connected to the communication network of another communication carrier C having the same connection point with the PSTN-GW 1a.
(Pattern 3)
When a call is received from the communication network of the communication carrier A to the terminal 6 of the subscriber accommodated in the relay connection carrier network.

  A specific processing procedure will be described for the patterns 1, 2, and 3. In the present embodiment, SIP is used as the control protocol in the IP network and ISUP is used as the control protocol in the PSTN. However, the present invention is not limited to this, and can be applied to other protocols. Is possible.

  FIG. 3 shows a communication connection according to the present embodiment, in which the communication network A (PSTN) of the communication carrier A is connected to the communication network (PSTN) of the communication carrier B via the relay connection operator network (IP network). It is a sequence diagram explaining the flow of a process in case it is performed (pattern 1).

  First, the PSTN-GW 1a receives an incoming call request signal (call signal) (IAM) from the communication network of the communication carrier A (S101). Then, the reception control unit 11a of the PSTN-GW 1a that has received the incoming call request signal (IAM) outputs the incoming call request signal (IAM) to the DB access unit 12a. Then, the DB access unit 12a generates relay determination request information including the called number information attached to the incoming call request signal (IAM) and transmits it to the relay determination DB device 2 (S102).

  When receiving the relay determination request information, the relay determination processing unit 20 of the relay determination DB device 2 refers to the relay determination DB 200 using the called number information of the incoming call request signal (IAM) as a key, and sets the target incoming call request signal. It is determined whether (IAM) is a relay connection or an incoming IP network. Here, it is assumed that the relay determination processing unit 20 determines that the connection is relay connection. Then, the relay determination processing unit 20 returns the determination to the relay connection as response information to the PSTN-GW 1a that has transmitted the relay determination request information (S103).

  When the response information indicating that the connection is relay connection is received from the relay determination DB device 2, the encapsulation target call storage control unit 13 of the PSTN-GW 1a stores the fact that the call (incoming call request signal) is a relay connection call. To remember. The protocol converter 14 converts the ISUP IAM message into a SIP INVITE message, and the encapsulation processor 15 encapsulates the received ISUP message (IAM) (S104). Subsequently, the routing unit (first routing unit) 17a transmits INVITE (IAM) to the relay server 3 in its own IP network (S105). Here, INVITE (IAM) represents a SIP INVITE message obtained by encapsulating an ISUP IAM signal. Then, the PSTN-GW 1a transmits a response signal (ACM) to the communication network of the communication carrier A (S106).

  The relay server 3 that has received INVITE (IAM) transmits INVITE (IAM) to the PSTN-GW 1b connected to the communication network of the carrier B based on the information in the header part of the INVITE message (S107).

  The PSTN-GW 1b encapsulated call storage control unit 13b that received INVITE (IAM) indicates that the call is a relay connection call because the ISUP signal encapsulated in INVITE (IAM) is attached. Store in the storage unit. Then, the decapsulation unit 16b decapsulates the ISUP signal information encapsulated in INVITE (IAM) and converts it into an ISUP signal (IAM) (decapsulation) (S108). 2 routing part) 17b transmits an IAM message to the communication network of carrier B (S109).

  Next, the PSTN-GW 1b receives a response signal (ACM) from the communication network of the communication carrier B (S110), and subsequently receives a call signal (CPG) indicating that a call is being made from the communication network of the communication carrier B. (S111). The encapsulation target call storage control unit 13b of the PSTN-GW 1b confirms that the storage unit stores that the call (the incoming call request signal that is the basis of the response signal) is a relay connection call. Then, without the DB access unit 12b making an inquiry request to the relay determination DB device 2 (transmission of relay determination request information), the protocol conversion unit 14b converts the protocol of the ISUP CPG message into a SIP 180 message, and the capsule. The processing unit 15b encapsulates the received ISUP message (CPG) (S112). Subsequently, the routing unit 17b transmits 180 (CPG) to the relay server 3 in its own IP network (S113). Here, 180 (CPG) represents an SIP 180 message obtained by encapsulating an ISUP CPG signal.

  The relay server 3 that has received 180 (CPG) transmits 180 (CPG) to the PSTN-GW 1a (S114).

  Since the PSTN-GW 1a that has received 180 (CPG) has an ISUP signal encapsulated in 180 (CPG), the decapsulation unit 16a has the ISUP signal information encapsulated in 180 (CPG). Is decapsulated and converted into an ISUP signal (CPG) (decapsulation) (S115), and the routing unit 17a transmits a CPG message to the communication network of the carrier A (S116).

  Next, when the PSTN-GW 1b receives a response signal (ANM) indicating that the incoming terminal has responded from the communication network of the carrier B (S117), the encapsulation target call storage control unit 13b of the PSTN-GW 1b It is confirmed that the storage unit stores that the call (the incoming call request signal that is the basis of the response signal) is a relay connection call. Then, the protocol converter 14b converts the ISUP ANM message into a SIP 200 message, and the encapsulation processor 15b encapsulates the received ISUP message (ANM) (S118). Subsequently, the routing unit 17b transmits 200 (ANM) to the relay server 3 in its own IP network (S119). Here, 200 (ANM) represents a SIP 200 message obtained by encapsulating an ISUP ANM signal.

  The relay server 3 that has received 200 (ANM) transmits 200 (ANM) to the PSTN-GW 1a (S120).

  Since the PSTN-GW 1a that has received 200 (ANM) has an ISUP signal encapsulated in 200 (ANM), the decapsulation unit 16a has the ISUP signal information encapsulated in 200 (ANM). Is decapsulated and converted into an ISUP signal (ANM) (decapsulation) (S121), and the routing unit 17a transmits an ANM message to the communication network of the carrier A (S122).

  Also in the subsequent signal processing, when the PSTN-GW 1a and PSTN-GW 1b receive the ISUP message (call control signal transmitted in response to the incoming call request signal), the PSTN-GW 1a and PSTN-GW 1b indicate that the call is a relay connection call. Confirmation is made by referring to the storage unit, and protocol conversion to SIP and encapsulation processing of the ISUP signal are performed. By storing that the call is a relay connection call in its own storage unit, it is possible to eliminate an inquiry to the relay determination DB device 2 by the DB access unit 12. Further, when the PSTN-GW 1a and the PSTN-GW 1b receive the SIP message in which the ISUP signal is encapsulated, the PSTN-GW 1a and the PSTN-GW 1b perform decapsulation and relay each signal.

  In this way, a transparent relay connection service can be provided in the relay between the respective carriers of the PSTN-IP network-PSTN.

  FIG. 4 shows the communication system according to the present embodiment, in which the communication network A (PSTN) of the communication carrier A is relay-connected to the communication network (PSTN) of another communication carrier C having a connection point to the same PSTN-GW 1a. FIG. 11 is a sequence diagram for explaining the flow of processing in the case of (pattern 2). 2, the communication network of the communication carrier A and the communication network of the communication carrier C have connection points on the same PSTN-GW 1a.

  First, the PSTN-GW 1a receives an incoming call request signal (call signal) (IAM) from the communication network of the communication carrier A (S201). Then, the reception control unit 11a of the PSTN-GW 1a that has received the incoming call request signal (IAM) outputs the incoming call request signal (IAM) to the DB access unit 12a. Then, the DB access unit 12a generates relay determination request information including the called number information attached to the incoming call request signal (IAM), and transmits it to the relay determination DB device 2 (S202).

  When receiving the relay determination request information, the relay determination processing unit 20 of the relay determination DB device 2 refers to the relay determination DB 200 using the called number information of the incoming call request signal (IAM) as a key, and sets the target incoming call request signal. It is determined whether (IAM) is a relay connection or an incoming IP network. Here, it is assumed that the relay determination processing unit 20 determines that the connection is relay connection. Then, the relay determination processing unit 20 returns the determination to the relay connection as response information to the PSTN-GW 1a that has transmitted the relay determination request information (S203). At this time, the relay determination processing unit 20 may add response information indicating that the relay destination is PSTN-GW1a as additional information, and send it back to PSTN-GW1a.

  When receiving response information indicating relay connection from the relay determination DB device 2, the encapsulation target call storage control unit 13a of the PSTN-GW 1a stores in the storage unit that the call is relay connection. Then, the protocol conversion unit 14a converts the ISUP IAM message into a SIP INVITE message, and the encapsulation processing unit 15a encapsulates the received ISUP message (IAM) (S204).

  Next, the routing unit (first routing unit) 17a determines that the transmission destination of INVITE (IAM) is the communication network (PSTN) of the communication carrier C having a connection point with its own PSTN-GW 1a, The signal is output to the decapsulation unit 16a. Subsequently, the decapsulation unit 16a decapsulates the ISUP signal information encapsulated in INVITE (IAM), converts it to an ISUP signal (IAM) (decapsulation) (S205), and the routing unit 17a. The IAM message which is the ISUP signal converted by is transmitted to the carrier C (S206).

  Note that when the PSTN-GW 1a acquires from the relay determination DB apparatus 2 that the call relay destination is its own PSTN-GW 1a as additional information of response information, or the protocol conversion unit 14a and the encapsulation processing unit 15a. In the case where the routing unit 17a performs the process of determining the routing destination of the call before the process according to, the protocol conversion process by the protocol conversion unit 14a, the encapsulation process by the encapsulation processing unit 15 (S204), Further, the decapsulation process (S205) by the decapsulation unit 16 can be prevented from being performed. In this case, the PSTN-GW 1a stores in the storage unit that the call is a relay connection based on the response information from the relay determination DB device 2, and then the routing unit 17a sends the IAM message to the communication carrier C as it is. Forward.

  Next, when the PSTN-GW 1a receives the response signal (ACM) from the communication network of the communication carrier C (S207), the encapsulation target call storage control unit 13a stores that the call is a relay connection call. In the PSTN-GW1a, the protocol conversion process, the encapsulation process, and the decapsulation process are performed as described above, or these processes are not performed, and a response is made. A signal (ACM) is transmitted to the carrier A (S208).

  The PSTN-GW 1a performs the same processing as S207 and S208, receives the call signal (CPG) from the communication network of the communication carrier C (S209), and sends the call signal (CPG) to the communication carrier A. (S210). Subsequently, the PSTN-GW 1a receives a response signal (ANM) from the communication network of the communication carrier C (S211), and transmits the response signal (ANM) to the communication network of the communication carrier A (S212).

  By doing in this way, it can relay-connect to the communication network (PSTN) of the other communication carrier which has a connection point in the same PSTN-GW1.

  FIG. 5 is a sequence diagram for explaining the flow of processing in the case where an incoming call is received at the terminal 6 of the subscriber accommodated in the relay connection carrier network (pattern 3) in the communication system according to the present embodiment.

  First, the PSTN-GW 1a receives an incoming call request signal (call signal) (IAM) from the communication network of the communication carrier A (S301). Then, the reception control unit 11a of the PSTN-GW 1a that has received the incoming call request signal (IAM) outputs the incoming call request signal (IAM) to the DB access unit 12a. Then, the DB access unit 12a generates relay determination request information including the called number information attached to the incoming call request signal (IAM), and transmits it to the relay determination DB device 2 (S302).

  When receiving the relay determination request information, the relay determination processing unit 20 of the relay determination DB device 2 refers to the relay determination DB 200 using the called number information of the incoming call request signal (IAM) as a key, and sets the target incoming call request signal. It is determined whether (IAM) is a relay connection or an incoming IP network. Here, it is assumed that the relay determination processing unit 20 determines that the incoming call is an own IP network. Then, the relay determination processing unit 20 returns the determination that it is an incoming IP network as response information to the PSTN-GW 1a that transmitted the relay determination request information (S303).

  When the response information indicating that the incoming call is an incoming IP network is received from the relay determination DB device 2, the protocol conversion unit 14a of the PSTN-GW 1a converts the ISUP IAM message into a SIP INVITE message, and the routing unit 17a Then, INVITE is transmitted to the relay server 3 in its own IP network (S304). In other words, here, the storage in the storage unit that is the relay connection by the encapsulation target call storage control unit 13 and the encapsulation processing by the encapsulation processing unit 15 are not performed. Then, the PSTN-GW 1a transmits a response signal (ACM) to the communication network of the communication carrier A (S305).

  Subsequently, the relay server 3 transmits INVITE from the information in the header part of INVITE to the subscriber server 4 in its own IP network (S306). Then, the subscriber server 4 transmits the INVITE to the IP conversion device 5 connected to the terminal 6 as the transmission destination (S307).

  Next, the PSTN-GW 1a receives a 180 message as a call signal from the IP conversion device 5 via the subscriber server 4 and the relay server 3 (S308 to S310). Then, the encapsulation target call storage control unit 13a confirms that the storage unit does not store that the call is a relay connection call, and the protocol conversion unit 14a transmits the SIP 180 message to the ISUP call signal. The data is converted into (CPG), and the routing unit 17a transmits it to the communication network of the communication carrier A (S311). That is, the encapsulation target call storage control unit 13a confirms that the fact that the call is a relay connection call is not stored in the storage unit, so that the encapsulation processing unit 15a performs encapsulation processing or decapsulation. It is possible to prevent the decapsulation process from being performed by the unit 16a.

  Subsequently, the PSTN-GW 1a receives a 200 message as a response signal from the receiving terminal 6 from the IP conversion device 5 via the subscriber server 4 and the relay server 3 (S312 to S314). Then, the encapsulation target call storage control unit 13a confirms that the storage unit does not store that the call is a relay connection call, and the protocol conversion unit 14a transmits the SIP 200 message to the ISUP response signal. The data is converted into (ANM) and transmitted to the communication network of the communication carrier A (S315). Subsequently, the PSTN-GW 1a transmits a response confirmation signal (ACK) to the IP conversion device 5 (S316 to S318).

  By doing so, the PSTN-GW 1a does not perform the process of encapsulating the ISUP signal in the SIP message when it arrives at the terminal 6 of the subscriber accommodated in the relay connection carrier network. Can do. Therefore, according to the communication method and the communication system according to the present embodiment, it is possible to prevent an increase in message size in the IP network that performs relay connection and to perform efficient relay.

1 PSTN-GW (gateway device)
2 Relay determination DB device 3 Relay server 4 Subscriber server 5 IP conversion device 6 Terminal 7 IGS (gateway exchange)
8 IC (relay exchange)
9 GC (Subscriber Exchange)
DESCRIPTION OF SYMBOLS 11 Reception control part 12 DB access part 13 Encapsulation object call memory | storage control part 14 Protocol conversion part 15 Encapsulation process part 16 Encapsulation release part 17 Routing part 20 Relay judgment process part 200 Relay judgment DB

Claims (7)

The communication serving as the transmission source is connected to the IP network of the relay connection carrier that relays the incoming call request signal received from the communication network of the transmission carrier serving as the transmission source to the communication network of the other communication carrier serving as the transmission destination. The originating gateway device that receives the signal transmitted from the PSTN of the carrier, and the call request signal is a call that is relay-connected to the communication network of another communication carrier that is the transmission destination, or the relay Relay judgment DB device for storing a relay judgment DB for each called number information attached to the incoming call request signal indicating whether the call is received at a terminal accommodated in a subscriber server in the IP network of the connection carrier A communication method used in a communication system for providing a relay connection service,
The originating gateway device is
Receiving the incoming call request signal from the communication network of the carrier serving as the transmission source, and transmitting relay determination request information including the incoming call number information attached to the incoming call request signal to the relay determination DB device;
The relay determination DB device
With reference to the relay determination DB using the called number information of the relay determination request information as a key, whether the incoming call request signal is a call that is relay-connected to the communication network of another communication carrier that is the transmission destination, Alternatively, it is determined whether the call is an incoming call in the IP network of the relay connection carrier, and the determination result is transmitted to the gateway device on the calling side,
The originating gateway device is
When the incoming call request signal receives a determination result that it is an incoming call in the IP network of the relay connection operator,
Protocol conversion of the incoming call request signal into an incoming call request IP signal used in the IP network,
A communication method, comprising: transmitting an IP signal of the incoming call request to the terminal via a subscriber server of the IP network and an IP conversion apparatus connected to the terminal as a destination. The relay connection provider's IP network further comprises a destination gateway device connected to the PSTN of another communication provider serving as the transmission destination,
The originating gateway device is
When receiving a determination result that the incoming call request signal is a call to be relay-connected to a communication network of another communication carrier serving as the transmission destination from the relay determination DB device,
Protocol conversion of the incoming call request signal into an incoming call request IP signal used in the IP network,
Encapsulating the incoming call request signal in the IP signal of the incoming call request, and sending it to the gateway device on the called side;
The gateway device on the called side is
When the incoming call request signal encapsulated in the incoming call request signal is received, the encapsulated incoming call request signal is decapsulated and converted into an incoming call request signal used in the PSTN. ,
The communication method according to claim 1, wherein the incoming call request signal is transmitted to a communication network of another communication carrier serving as the transmission destination. The originating gateway device is
When receiving a determination result that the incoming call request signal is a call to be relay-connected to a communication network of another communication carrier serving as the transmission destination from the relay determination DB device,
When the communication network of the other carrier serving as the transmission destination is connected to the gateway device on the originating side,
The communication method according to claim 2, wherein the incoming call request signal is transferred to a communication network of another communication carrier that is the transmission destination. The originating gateway device is
When receiving a determination result that the incoming call request signal is a call to be relay-connected to a communication network of another communication carrier serving as the transmission destination from the relay determination DB device,
The incoming call request signal is stored in the storage unit of the originating gateway device that the call is a relay connection call,
When a call control signal transmitted in response to the incoming call request signal is received from the communication network of the communication carrier serving as the transmission source, the incoming call request signal is stored in the storage unit as the call to be relay-connected. Make sure that
Protocol conversion of the call control signal into a call control IP signal used in the IP network;
Encapsulating the call control signal in the IP signal of the call control and transmitting it to the gateway device on the called side;
The gateway device on the called side is
When the call control IP signal encapsulated in the call control signal is received, the encapsulated call control signal is decapsulated and converted into a call control signal used in the PSTN,
The communication method according to claim 2, wherein the call control signal is transmitted to a communication network of another communication carrier serving as the transmission destination. The gateway device on the called side is
When the incoming call request IP signal encapsulated in the incoming call request signal is received from the gateway device on the calling side,
The call reception request signal is stored in the storage unit of the gateway device on the called side as a call to be relay-connected to a communication network of another communication carrier serving as the transmission destination,
When a call control signal transmitted in response to the incoming call request signal is received from a communication network of another communication carrier serving as the transmission destination, the incoming call request signal is relayed to the storage unit. Make sure it is remembered as
Protocol conversion of the call control signal into a call control IP signal used in the IP network;
The call control signal is encapsulated in the IP signal of the call control and transmitted to the gateway device on the calling side.
The originating gateway device is
When the call control IP signal encapsulated in the call control signal is received, the encapsulated call control signal is decapsulated and converted into a call control signal used in the PSTN,
The communication method according to claim 4, wherein the call control signal is transmitted to a communication network of a communication carrier that is the transmission source. The communication serving as the transmission source is connected to the IP network of the relay connection carrier that relays the incoming call request signal received from the communication network of the transmission carrier serving as the transmission source to the communication network of the other communication carrier serving as the transmission destination. The originating gateway device that receives the signal transmitted from the PSTN of the carrier, and the call request signal is a call that is relay-connected to the communication network of another communication carrier that is the transmission destination, or the relay Relay judgment DB device for storing a relay judgment DB for each called number information attached to the incoming call request signal indicating whether the call is received at a terminal accommodated in a subscriber server in the IP network of the connection carrier A communication system that provides a relay connection service,
The originating gateway device is
A reception control unit for receiving the incoming call request signal from the communication network of the carrier serving as the transmission source;
A DB access unit for transmitting relay determination request information including the called number information attached to the received incoming call request signal to the relay determination DB device;
When receiving a determination result from the relay determination DB device that the incoming call request signal is an incoming call in the IP network of the relay connection carrier, the incoming call request signal is used in the IP network. A protocol conversion unit that converts the protocol into a call request IP signal;
A first routing unit that transmits an IP signal of the incoming call request to the terminal via a subscriber server of the IP network and an IP conversion device connected to the terminal as a destination. ,
The relay determination DB device
The relay determination DB;
With reference to the relay determination DB using the called party number information of the relay determination request information received from the originating gateway device as a key, the incoming call request signal is a communication network of another communication carrier serving as the transmission destination A relay determination processing unit for determining whether the call is a relay connection call or an incoming call in the relay connection provider's IP network, and transmitting the determination result to the originating gateway device; A communication system characterized by comprising: The relay connection provider's IP network further comprises a destination gateway device connected to the PSTN of another communication provider serving as the transmission destination,
The originating gateway device is
If the protocol conversion unit receives a determination result from the relay determination DB device that the incoming call request signal is a call to be relay-connected to the communication network of another communication carrier as the transmission destination, the protocol conversion unit converts the protocol conversion An encapsulation processing unit that encapsulates the incoming call request signal in the incoming call request IP signal;
The first routing unit transmits an IP signal of the incoming call request in which the incoming call request signal is encapsulated to the gateway device on the incoming side;
The gateway device on the called side is
When the incoming call request IP signal encapsulated in the incoming call request signal is received, the encapsulated incoming call request signal is unencapsulated and converted into an incoming call request signal used in the PSTN. A decapsulation unit;
And a second routing unit for transmitting an incoming call request signal used in the PSTN converted by the decapsulation unit to a communication network of another communication carrier as the transmission destination. Item 7. The communication system according to Item 6.

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