JP2010193046A - Call routing method and call routing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a call routing method and a call routing system which surely can attain a call routing to a destination by reducing burdens of a relay server. <P>SOLUTION: The call routing method includes: a step of transferring a call setting request message to a relay server when a destination address included in the call setting request message transmitted from a calling terminal is not a terminal stored in a subscriber session control server itself; a step of allowing the relay server to transfer the call setting request message to a number management means without referring to a destination address; a step of allowing the number management means to return a redirect message including a logical address and a table number corresponding to the destination address to the relay server; a step of transmitting the call setting request message to a terminating side subscriber session control server corresponding to the logical address redirected to the relay server; and a step of transferring the call setting request message received by the terminating side subscriber session control server to a terminating terminal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a call routing method and call routing in an integrated communication network that integrates a next-generation network (next-generation IP network) using IP technology, a PSTN (Public Switched Telephone Networks), an IP telephone service network, and the like. About the system.

  In recent years, the Internet has become widespread, and various information has been acquired and exchanged. In addition, the demand for high-speed and stable quality broadband access has increased, and the spread of optical fiber has replaced the conventional copper wire subscriber line. The number of subscribers to FTTH (Fiber To The Home), a domestic optical access service, is increasing. Is over 10 million. With the spread of such communication infrastructure, IP telephones using packet communication protocol IP (Internet Protocol) technology are also rapidly spreading.

  For this reason, communication service providers are developing next-generation networks (NGN: Next Generation Network) as IP networks that integrate telephone services and video communication services. For example, in Non-Patent Document 1, TISI (European Communications Standards Institute: European Telecommunications Standards Organization) Technical Committee TISPAN (Telecoms & Internet converged Services & ProtocolsN Trend Introduction). Non-Patent Document 2 introduces a technology that supports NGN, and introduces a client identification technology on the Internet, a routing technology that selects a communication path based on an IP address, and the like.

  On the other hand, PSTN, which has been used for many years as the center of the general telephone network, forms a hierarchical switching network and is called based on telephone numbers assigned by a global number structure (country code, area code, etc.). The communication path is selected. Such an existing telephone network has established robust security and multi-functionality, but has a problem that the system is closed and expensive (for example, see Non-Patent Document 3). On the other hand, IP networks have security and quality issues, but have the advantage that they can be managed independently on the user side and the network can be constructed at low cost. Therefore, great expectations are placed on the development of NGN that combines the advantages of both the existing telephone network and IP network.

  Recently, IP telephone services that can be used in the same manner as general subscriber telephone services using VoIP technology in CATV lines, optical fiber lines, and the like are rapidly spreading. Such IP telephones are interconnected to existing telephone networks and are assigned not only unique telephone numbers that use the IP networks of the respective telecommunications carriers, but also the same telephone numbers as general subscriber telephones. Services that can be assigned are also provided.

  In applications such as IP telephones that require real-time performance, SIP (Session Initiation Protocol) is generally used for creating, changing, and disconnecting sessions. In SIP, a call setup request message (INVITE message) is sent from the originating terminal to the network side in order to generate a call, and the network side subscriber system server (subscriber session control server) or relay server (relay session control server) ) To connect to the destination terminal.

  For example, in the prior art shown in FIG. 11, when the user of the destination subscriber terminal B moves from the subscriber server b to the subscriber server c, the subscriber terminal B transmitted from the subscriber terminal A is sent. A call setting request message (INVITE message (destination: subscriber terminal B)) is received by the subscriber server b of the original accommodation destination via the subscriber server a and the relay server z. However, since there is no subscriber terminal B (actually the terminal with the telephone number assigned to the subscriber terminal B) under the subscriber server b, the subscriber server B is under the control of its own server. An error message indicating that the message does not exist is returned to the relay server z. This error message is sent back to the sender in the reverse order of the outgoing call. In this case, the subscriber terminal A cannot connect to the subscriber terminal B.

  In order to solve this, for example, in another prior art shown in FIG. 12, the relay server z preliminarily manages in which subscriber server the subscriber terminal B is accommodated. . That is, since the relay server z knows in advance that the subscriber terminal B has moved to the subscriber server c, when an INVITE message is sent from the subscriber terminal A to the relay server z as in FIG. The relay server z forwards the INVITE message to the subscriber server c instead of sending it to the subscriber server b which is the original accommodation destination of the subscriber terminal B. Then, the subscriber server c transfers the INVITE message to the subscriber terminal B that is the destination, so that the subscriber terminal A can connect to the subscriber terminal B.

  However, in the prior art, in order for the relay server to resolve the number (select the routing route to the destination terminal), the telephone numbers of all the terminals must be centrally managed, and the burden on the relay server increases. There was a problem of high costs. In particular, it supports number portability services (services that allow the same telephone number to be used even if the operator is changed: a function is required to transfer the old subscriber's phone number to other operators in order to realize this service) In order to reliably route calls to destinations by performing number resolution, the burden on the relay server increases, including system scalability issues such as presence services (management of connection status for each user or terminal). There was a problem.

  In view of the above problems, an object of the present invention is to provide a call routing method and a call routing method that can reduce the burden on a relay server and reliably route a call to a destination in an integrated communication network in which an existing telephone network and an IP network are integrated. It is to provide a routing system.

  The call routing method according to claim 1 of the present invention is a call routing method used in an integrated communication network in which a plurality of networks managed independently are integrated, and is connected to a first network of the plurality of networks. Transmitting a call setting request message to a subscriber session control server accommodating the calling terminal, and the subscriber session control server has a destination address of the receiving terminal included in the call setting request message Determining whether the subscriber session control server itself is an accommodation terminal, and transferring the call setting request message to the relay server when the subscriber session control server is not an accommodation terminal; the relay server refers to the destination address And transferring the call setting request message to the number management means, and the number management means Searching a logical address corresponding to the destination address based on a management table and returning a redirect message including the logical address and a table number to the relay server; and the redirect message redirected to the relay server Transmitting the call setup request message to a terminating subscriber session control server accommodating a terminating terminal connected to any one of the plurality of networks corresponding to a logical address; and the terminating subscriber session control server includes: Transferring the received call setting request message to a receiving terminal corresponding to the table number.

  The call routing method according to claim 2 of the present invention is the call routing method according to claim 1, wherein the relay server is a destination address that is not managed by the number management means of the first network of the plurality of networks. In this case, the call setup request message is sequentially transferred to number management means of another network of the plurality of networks.

  A call routing method according to claim 3 of the present invention is the call routing method according to claim 1 or 2, wherein when a call over a plurality of integrated communication networks is routed, the caller first integration is performed. When transferring from the second integrated communication network to which the call setting request message has been transferred from the communication network to the third integrated communication network, the call setting request message is transmitted via the first integrated communication network of the transmission source. The method includes the step of transferring.

  A call routing method according to a fourth aspect of the present invention is the call routing method according to any one of the first to third aspects, wherein the number management means is configured such that the incoming terminal moves with number portability. In the case of routing across a terminal or a plurality of integrated communication networks, the logical address is composed of a transfer destination address (NRN) and returned to the relay server.

  The call routing method according to claim 5 of the present invention is the call routing method according to claim 4, wherein the number management means relays two numbers of a transfer destination address (NRN) and a table number. It has the step which returns to a server, It is characterized by the above-mentioned.

  A call routing method according to claim 6 of the present invention is the call routing method according to any one of claims 1 to 3, wherein a plurality of subscriber session controls of a number management source in which the same number band is accommodated. When there is a server, the plurality of subscriber session control servers of the number management source have a step of expanding the destination address into an SRN.

  The call routing method according to claim 7 of the present invention is the call routing method according to claim 6, wherein a terminal connected to a subscriber session control server that is not a number management source is a calling terminal. A plurality of subscriber session control servers as management sources have a step of returning a redirect message including a table number in which the destination address is expanded to an SRN to the relay server.

  The call routing method according to claim 8 of the present invention is the call routing method according to claim 6 or 7, wherein the terminal connected to the subscriber session control server of the number management source is the calling terminal, The subscriber session control server to which the calling terminal is connected has a step of bypassing to the relay server when it cannot connect to the subscriber session control server to which the receiving terminal is connected.

  A call routing method according to a ninth aspect of the present invention is the call routing method according to any one of the first to eighth aspects, wherein when one of the transfer destination networks is a PSTN, the call routing method is expanded to an NRN. The call setting request message is converted into an IAM message by the relay server and transferred.

  A call routing system according to claim 10 of the present invention is an integrated communication network in which a plurality of independently managed networks including a first network having a subscriber session control server and a relay server are integrated. A logical address corresponding to the destination address of the called terminal included in the call setting request message from the calling terminal transferred from the relay server, based on an address management table held by itself Number management means for creating a redirect message including a logical address and a table number and returning it to the relay server is provided, and the subscriber session control server receives an incoming call included in a call setup request message received from a calling terminal accommodated by itself. If the destination address of the terminal is its own accommodation terminal, The call setup request message is forwarded to the relay server, and the relay server forwards the call setup request message to the number management means without referring to the destination address forwarded from the subscriber session control server. The subscriber session control server is configured to receive a terminating subscriber session that accommodates a terminating terminal connected to any one of the plurality of networks corresponding to the logical address of the redirect message redirected to the relay server. The call setup request message is transmitted to a server.

  The call routing system according to claim 11 of the present invention is the call routing system according to claim 10, wherein the relay server is a destination address that is not managed by the number management means of the first network of the plurality of networks. In this case, the call setup request message is transferred in order to the number management means of another network of the plurality of networks.

  A call routing system according to claim 12 of the present invention is the call routing system according to claim 10 or 11, wherein when a call over a plurality of integrated communication networks is routed, the caller first integration The relay server of the second integrated communication network to which the call setting request message has been transferred from the communication network is configured to transfer the call setting request message to the third integrated communication network. The call setup request message is transferred via a network.

  A call routing system according to a thirteenth aspect of the present invention is the call routing system according to any one of the tenth to twelfth aspects, wherein the number management means is configured to allow a user who has moved the destination terminal with number portability. In the case of routing across a terminal or a plurality of integrated communication networks, the logical address is composed of a transfer destination address (NRN) and returned to the relay server.

  According to a fourteenth aspect of the present invention, in the call routing system according to the thirteenth aspect, the number managing means relays two numbers, a transfer destination address (NRN) and a table number. It is returned to the server.

  A call routing system according to a fifteenth aspect of the present invention is the call routing system according to any one of the tenth to twelfth aspects, wherein a plurality of subscriber session controls of a number management source in which the same number band is accommodated. When there is a server, the plurality of subscriber session control servers of the number management source develops the destination address in the SRN.

  The call routing system according to claim 16 of the present invention is the call routing system according to claim 15, wherein a terminal connected to a subscriber session control server that is not a number management source is a calling terminal. A plurality of subscriber session control servers as management sources return a redirect message including a table number in which the destination address is expanded to an SRN to the relay server.

  The call routing system according to claim 17 of the present invention is the call routing system according to claim 15 or 16, wherein the terminal connected to the subscriber session control server of the number management source is the calling terminal. The subscriber session control server to which the calling terminal is connected has a step of bypassing to the relay server when it cannot connect to the subscriber session control server to which the receiving terminal is connected.

  Further, the call routing system according to claim 18 of the present invention is the call routing system according to any one of claims 10 to 17, wherein when one of the transfer destination networks is PSTN, the call routing system is expanded to NRN. The call setting request message is converted into an IAM message by the relay server and transferred.

  The call routing method and call routing system according to the present invention can reduce the burden on a relay server and reliably route a call to a destination in an integrated communication network in which an existing telephone network and an IP network are integrated. In particular, call routing corresponding to the number portability service can be realized.

It is explanatory drawing which shows the system configuration example of an integrated communication network. It is explanatory drawing for demonstrating the call routing in a self-integrated communication network. It is explanatory drawing for demonstrating the call routing between several integrated communication networks. It is explanatory drawing for demonstrating call routing in case a some integrated communication network is shared by the common next generation network. It is explanatory drawing which shows the flow of call routing at the time of originating from the terminal connected to the subscriber session control server which is not a number management origin, when the same number belt | band | zone is accommodated in several subscriber session control servers. . It is explanatory drawing which shows the flow of call routing at the time of originating from the terminal connected to the subscriber session control server of the number management origin, when the same number belt | band | zone is accommodated in several subscriber session control servers. It is explanatory drawing which showed the example of a setting of the host part information of URI of an INVITE message. It is explanatory drawing which showed an example of the call routing method when the user of PSTN moves to another provider by number portability. It is explanatory drawing which showed an example of the call routing method when a next-generation network user moves to the next-generation network of another provider by number portability. It is explanatory drawing which showed an example of the call routing method when a next-generation network user moves to PSTN using number portability. It is explanatory drawing which shows the prior art 1. FIG. It is explanatory drawing which shows the prior art 2. FIG.

  Hereinafter, embodiments of a call routing method and a call routing system according to the present invention will be described in detail with reference to the drawings. Note that the call routing method and call routing system according to the present embodiment does not need to perform the number resolution by managing the telephone number of each user's subscriber terminal in the relay session control server (relay server) as in the past, In particular, even for a user who uses a number portability service, the destination address is routed by expanding the number using an NRN (Network Routing Number), thus reducing the burden on the relay session control server. be able to.

  FIG. 1 shows a system configuration example of an integrated communication network. In FIG. 1, the integrated communication network 101 includes a next generation network (NGN) 110, a PSTN 111, an IP telephone service network (CAS network) 112, and a linkage server (RLS) 113. Further, the NGN 110 is connected to another carrier network 102.

  In FIG. 1, call routing (routing for establishing a call between a caller and a callee) is basically performed for each communication carrier, that is, in the integrated communication network 101 or another communication carrier network 102. . Further, the PSTN 111 and the IP telephone service network 112 in the integrated communication network 101 perform call routing based on their unique number bands, but number portability that allows the same telephone number to be moved and used between different operators. In order to cope with this, it is expanded to the NRN number and routed to the called party.

  In addition, when a call is made from NGN 110, the number is resolved within the NGN 110's own network, but if the number cannot be resolved, the cooperation server 113 is inquired, and the IP telephone service network 112 or PSTN 111 is routed in order according to the inquiry result. Resolve the number.

  Here, an example in which a call is routed in the integrated communication network 101 will be described with reference to FIG. FIG. 2 shows the same configuration of the integrated communication network 101 as in FIG. 1, and includes an NGN 101, a PSTN 111, and an IP telephone service network 112.

  In FIG. 2, NGN 110 has a subscriber session control server (SSC) 121, a relay session control server (ISC) 122, and a PSTN-GW 123. PSTN 111 is an IGS (Gateway Switch: Interconnecting Gateway Switch) 131 and a GC (Group Station). : Group Unit Center) 132, and the IP telephone service network 112 has a subscriber accommodation server 141.

  For the outgoing call from the subscriber terminal 114 of the next generation user connected to the NGN 110, the number is resolved within the local network of the NGN 110. If the number cannot be resolved, the cooperation server 113 is inquired, and the IP telephone service network is determined according to the inquiry result. 112 or PSTN 111. In the case of routing to the IP telephone service network 112, the number is resolved by the subscriber accommodation server 141. In the case of routing to the PSTN 111, the number is resolved by the GC 132 via the IGS 131. In particular, in the case of a user who uses number portability from the PSTN 111 to another carrier network, the number is expanded in the NRN of the other carrier network by the GC 132 and redirected to the PSTN-GW 123 on the NGN 110 side, and the relay session control server Route to the other carrier network via 122. An outgoing call from the subscriber terminal 115 connected to the IP telephone service network 112 is routed to the relay session control server 122 of the belonging NGN 110. For outgoing calls from the subscriber terminal 116 connected to the PSTN 111, the number is resolved within the PSTN 111's own network, but if the destination is not a terminal within the PSTN 111, the number is expanded in the NRN and routed to the PSTN-GW 123 of the NGN 110 To do. Note that specific message exchange during routing will be described in detail later.

  Next, a configuration example when a call is routed between a plurality of integrated communication networks will be described. 3 includes two integrated communication networks, that is, an integrated communication network 201 and an integrated communication network 202. The integrated communication network 201 has an NGN 210a, and the integrated communication network 202 has an NGN 210b. In FIG. 3, call routing between two integrated communication networks basically performs call routing based on a unique number band for each of the integrated communication network 201 and the integrated communication network 202, and corresponds to number portability. Are deployed in the NRN managed by each integrated communication network for routing.

  For example, an outgoing call from the subscriber terminal 214a of the next generation user connected to the NGN 210a and an outgoing call from the subscriber terminal 215a connected to the IP telephone service network 212a are transmitted to the subscriber session control server 221a and the relay session control server. Routed via 222a. For outgoing calls that cannot be resolved by the NGN 210a, an inquiry is made to the cooperation server 213a, and the call is routed to the IP telephone service network 212a or the PSTN 211a according to the inquiry result. Alternatively, in the case of a user who uses number portability to the integrated communication network 202, the number is expanded in the NRN and routed to the integrated communication network 202 side via the relay session control server 222a of the NGN 210a. In response to this, the relay session control server 222b of the NGN 210b on the integrated communication network 202 side passes through the subscriber session control server 221b when the receiving terminal is in the NGN 210b, similarly to the relay session control server 122 described in FIG. If the number cannot be resolved within the NGN 210b, the number is resolved by routing to the IP telephone service network 212b or the PSTN 211b.

  In this way, a call is appropriately routed among a plurality of integrated communication networks each having an NGN, an IP telephone service network, and a PSTN. Note that specific message exchange during routing will be described in detail later.

  Next, a system example in which a plurality of integrated communication networks are shared by a common next generation network and relayed by a PSTN relay network will be described. FIG. 4 shows a system using a PSTN relay network in which the integrated communication network 301 and the integrated communication network 302 are shared by the NGN 310 and relayed between the PSTN relay network 303 of the first operator and the PSTN relay network 304 of the second operator. An example is shown. In FIG. 4, the integrated communication network 301 has an IP telephone service network 312a and a PSTN 311a. Separately, the integrated communication network 302 has an IP telephone service network 312b and a PSTN 311b. The PSTN 311 a of the integrated communication network 301 and the PSTN 311 b of the integrated communication network 302 are connected by the PSTN relay network 303 or the PSTN relay network 304.

  In FIG. 4, the outgoing call from the subscriber terminal 314a of the next generation user connected to the integrated communication network 301 or the outgoing call from the subscriber terminal 315a connected to the IP telephone service network 312a is a subscriber session in the NGN 310. Routing is performed via the control server 321 and the relay session control server 322 to the relay session control server 323 of the integrated communication network 302 shared by the same NGN 310. If the number can be resolved by the NGN 310, the number is resolved and routed to the destination, but if the number cannot be resolved by the NGN 310, the cooperation server 313b is inquired, and the IP telephone service network 312b of the integrated communication network 302 or the The number is resolved by routing to the PSTN 311b.

  In addition, the outgoing call from the subscriber terminal 316a connected to the PSTN 311a of the integrated communication network 301 is resolved by the PSTN 311a, and the PSTN 311a of the integrated communication network 301 to the PSTN relay network 174 of the first operator or the second operator's PSTN 311a. Routing to the PSTN 311b of the integrated communication network 302 via the PSTN relay network 175. When the user of the destination terminal of the PSTN 311b as the routing destination uses number portability, the number is expanded in the NRN of the other carrier communication network by the GC 311c of the PSTN 311b and transferred to the relay session control server 323 which is the PSTN-GW of the NGN 310. Then, it is routed to the communication network of other carriers.

  In FIG. 4, of the outgoing calls from the subscriber terminal of the next-generation user connected to the NGN 310 on the integrated communication network 301 side or the IP telephone service network 312a, the outgoing call to the PSTN number band is the subscriber session control server 321. Then, a pre-suffix (additional number for identification) is assigned and routed to the PSTN 311b of the integrated communication network 302.

  As described above, even in a system in which a plurality of integrated communication networks are shared by a common next-generation network and relayed by a PSTN relay network of different operators, call routing can be appropriately performed. Note that specific message exchange during routing will be described in detail later.

  Next, a specific message exchange method when routing a call in the integrated communication network described with reference to FIGS. 1 to 4 will be described in detail with reference to FIGS.

  First, FIG. 5 shows an example of the case where the same number band is accommodated in a plurality of subscriber session control servers, and the flow of call routing when originating from a terminal connected to a subscriber session control server that is not the number management source. It is explanatory drawing which shows.

  In FIG. 5, a plurality of subscriber session control servers 502 (SRN (server routing number): 1), subscriber session control server 503 (SRN: 2), and subscriber session control server 504 (SRN: 3) The same number band is accommodated, and the destination subscriber terminal 505 is connected to the subscriber session control server 503.

  First, the originating subscriber terminal 507 accommodated in the subscriber session control server 506, which is not the number management source, calls a call setup request message for requesting connection to the subscriber terminal 505 of the next-generation IP user that is the destination. (INVITE message) is transmitted to the subscriber session control server 506. The INVITE message to which the Req-URI (table number @ IP-A) is added by the subscriber session control server 506 is transmitted from the subscriber session control server 506 to the relay session control server (IP-GW) 508 and the relay session control server 509. To the subscriber session control server 502 of the number management source. However, since the subscriber session control server 502 does not accommodate the subscriber terminal 505, the redirect session 301 (sip: table number; npdi; rn = SRN @ CL5) is returned to the relay session control server 509. Note that CL5 of the contact URI (*** @ CL5) is an identifier indicating a subscriber session control server. Receiving this, the relay session control server 509 transmits an INVITE message (sip: table number; npdi; rn = SRN @ CL5) to the next subscriber session control server 503. Since the subscriber session control server 503 accommodates the subscriber terminal 506, a call is established with the originating subscriber terminal 507.

  Here, in the above example, the subscriber session control server 502 corresponds to the number management means, and the address management table held by the subscriber session control server 502 (correspondence between the telephone number corresponding to the accommodated subscriber and the network address) A database that manages a destination address (for example, SRN @ CL5) corresponding to a destination address (for example, table number @ IP-A), and a subscriber session control server that accommodates a destination subscriber terminal 505 A redirect message including the logical address and table number of 503 is returned to the relay session control server 509.

  In this way, a call can be made between the subscriber terminal 507 of the next-generation IP user connected to the subscriber session control server 506 that is not the number management source and the subscriber terminal 505 of the number management source.

  Next, in FIG. 5, a description will be given of call routing when the user's subscriber terminal 511 connected to the PSTN 510 makes a call to the subscriber terminal 505 that is the number management source. The subscriber terminal 511 sends an R-IAM message (R-Initial Address Message) (calling number: NRN, called) to the PSTN relay server (PSTN-GW) 514 in the next generation network 501 via the GC 512 and the IGS 513 in the PSTN 510. Directory: table number). At this time, the destination address of the R-IAM message includes two numbers, a table number and an NRN. Note that the NRN in this case is a network routing number corresponding to the next generation network 501.

  The relay server 514 that has received the R-IAM message converts the R-IAM message into a SIP INVITE message (sip: table number; npdi; rn = NRN @ hostport) and transmits the converted message to the relay session control server 509. Receiving this, the relay session control server 509 transmits an INVITE message (sip: table number @hostport) to the subscriber session control server 504. However, since the subscriber session control server 504 does not accommodate the subscriber terminal 505, the redirect message 301 (sip: table number; npdi; rn = SRN @ CL5) is returned to the relay session control server 509. Receiving this, the relay session control server 509 transmits an INVITE message (sip: table number; npdi; rn = SRN @ CL5) to the next subscriber session control server 503. Since the subscriber session control server 503 accommodates the subscriber terminal 505, a call is established with the originating subscriber terminal 511, and the subscriber terminal 511 and the number connected to the PSTN 510 which is not the number management source. A call can be made with the subscriber terminal 505 of the management source.

  Here, in the above example, the subscriber session control server 504 corresponds to the number management means, and the logical address corresponding to the destination address (for example, table number @hostport) based on the address management table held by the subscriber session control server 504. The address (for example, SRN @ CL5) is searched, and a redirect message including the logical address and table number of the subscriber session control server 503 accommodating the destination subscriber terminal 505 is returned to the relay session control server 509.

  Thus, when there are a plurality of subscriber session control servers of the number management source in which the same number band is accommodated, even when making a call from a terminal connected to the subscriber session control server that is not the number management source, the number management source Since the destination address is expanded in the SRN and routed among the plurality of subscriber session control servers, it is possible to reliably connect to the receiving terminal.

  Next, FIG. 6 is used for a call routing method when a call is made from a terminal connected to a subscriber session control server as a number management source when the same number band is accommodated in a plurality of subscriber session control servers. I will explain.

  In FIG. 6, the same number band is accommodated in the subscriber session control server 522 and the subscriber session control server 523 of the next generation network 521, and the subscriber terminal 524 connected to the subscriber session control server 522 is subscribed. A state in which a call is sent to 525 to a subscriber terminal connected to the subscriber session control server 523 is depicted.

  First, the subscriber terminal 524 of the next generation IP user transmits a call setting request message (INVITE message) to the subscriber session control server 522. The subscriber session control server 522 recognizes that it is the destination number managed by itself and the number of the terminal accommodated by the subscriber session control server 523, and identifies the subscriber session control server 523. Route to the subscriber session control server 523 by the SRN. At this time, the INVITE message includes a table number (the number of the partner terminal 68 transmitted from the next-generation IP user terminal 66), a host name (SRN: 2 of the subscriber session control server 523, and a host name in the SPI-URI host part). @ CL5) is set. Then, the INVITE message is received from the subscriber session control server 522 to the subscriber terminal 525 via the subscriber session control server 523 that accommodates the subscriber terminal 525 by the table number.

  On the other hand, when the mesh line (separate route line) cannot be connected, the subscriber session control server 522 transmits an INVITE message to the relay session control server (IP-GW) 526 as a bypass route. The relay session control server 526 that has received the INVITE message from the subscriber session control server 522 routes to the subscriber session control server 523 by SRN (SRN: 2), and arrives at the subscriber terminal 525.

  Thus, when there are a plurality of subscriber session control servers of the number management source in which the same number band is accommodated, even when making a call from a terminal connected to the subscriber session control server of the number management source, the number management source Since the destination address is expanded in the SRN and routed between a plurality of subscriber session control servers, it is possible to reliably connect to the receiving terminal.

  Next, an example of setting URI host part information of a call setting request message (INVITE message) in call routing will be described with reference to FIG. In the example of FIG. 7, the subscriber terminal 534 connected to the company A PSTN 533 from the subscriber terminal 532 of the next generation IP user in the company A next generation network 531 and the subscriber of the next generation IP user of the company B next generation network 535. The state of routing when calling to the terminal 536 is depicted.

  In FIG. 7, the INVITE message transmitted from the subscriber terminal 532 of the next generation IP user is a subscriber session in the Osaka block 537 of the A company next generation network 531 that accommodates the subscriber terminal 532 of the next generation IP user. The INVITE message to which the Req-URI (E.164@domain (Company A)) is added by the control server 538 is sent from the subscriber session control server 538 to the relay session control server 539 in the Osaka block. E.E. Reference numeral 164 denotes a hierarchically described number, which corresponds to the destination telephone number here. The relay session control server 539 transfers the INVITE message to the relay session control server 541 in the Kansai block 540. First, it tries to resolve the number by transferring to the subscriber session control server 542 in the Kansai block, but if it cannot be resolved, the redirect message 301 is returned to the relay session control server 541. Note that CL4 in the contact URI (E.164@CL4) indicates a relay session control server.

  The relay session control server 541 that has received the redo message from the subscriber session control server 542 sends an INVITE message (E.164@CL4) to the cooperation server 543, but since the cooperation server 543 cannot resolve the number, the SIP response code Message 404 (not found) is returned to the relay session control server 541. Further, the relay session control server 541 sends an INVITE message (E.164@PSTN) to the PSTN-GW 544 that relays the connection to the company A PSTN 533, and is the number management source of the user via the IGS 545 in the company A PSTN 533. It is sent to the GC 546 and connected to the called terminal 534.

  In FIG. 7, when a call is transmitted from the subscriber terminal 539 of the next generation IP user to the subscriber terminal 536 connected to the B company next generation network 535, the relay session control of the Osaka block 537 is performed from the subscriber session control server 538. An INVITE message (E.164@domain (Company A)) is transmitted to the server 539, and an INVITE message (E.164@domain (E.164) is transmitted from the relay session control server 539 to the relay session control server 547 in the B company next-generation network 535. Company B)) is sent from the relay session control server 547 to the subscriber terminal 536 of the next-generation IP user via the subscriber session control server 548.

  In this manner, it is possible to perform routing in order by converting the host part information of the URI of the INVITE message transferred according to the routing destination.

  Next, a routing method when the users of the subscriber terminal 534 connected to the A company PSTN 533 and the subscriber terminal 536 connected to the B company next generation network 535 move with number portability will be described.

  FIG. 8 is an explanatory diagram showing an example of a call routing method when a user of the PSTN moves to another carrier IP network with number portability. The subscriber terminal 604 connected to the PSTN 603 of the B company next-generation network 602 is shown. The specific message exchange when the user moves to the other provider IP network 605 is shown.

  In FIG. 8, the next generation IP user connected to the A company next generation network 601 transmits a call setting request message (INVITE message) from the subscriber terminal 601a accommodated in the subscriber session control server 606. The INVITE message to which the Req-URI (table number @ IP-A) is added by the subscriber session control server 606 is sent from the subscriber session control server 606 to the relay session control server (IP-GW) 607, and the relay session control server In 607, it is converted to a Req-URI (table number @ IP-B) of the INVITE message, and the destination subscriber terminal 604 is sent to the B company next-generation network 602 side that was accommodated before the movement of the number portability.

  In the B company next generation network 602, the relay session control server (IP-GW, PSTN-GW) 608 of the A company next generation network 601 first receives the INVITE message transferred from the relay session control server 607 as the subscriber session control server 609. However, since the subscriber terminal 604 is not accommodated in the subscriber session control server 609, the subscriber session control server 609 returns the SIP response code redirect message 301 to the relay session control server 607. The relay session control server 607 that has received this sends an INVITE message to the link server 611 of the next IP telephone service network (CAS network) 610, but since the link server 611 does not accommodate the number, the SIP response code message 404 (not found) is returned to the relay session control server 608. Upon receiving this, the relay session control server 608 further converts the IAM message (added table number) to the GC 613 that is the user's number management source via the IGS 612 of the next PSTN 603 and transmits it. However, since the subscriber terminal 604 of the user has moved to the other carrier IP network 605 with number portability, the GC 613 sends an R-REL message in which the NRN of the other carrier IP network 605 of the transfer destination number is written to the IGS 612. Is returned to the relay session control server 608. The relay session control server 608 that has received the R-REL message in which the NRN of the transfer destination number is written notifies the preceding operator (source operator or relay operator) of redirection (movement) by number portability. Redirect message 301 (sip: table number; npdi; rn = NRN @ hostport) describing two numbers of the NRN and the table number of the transfer destination operator in the Contact URI of the message sender Next generation of company A of the source operator It is returned to the relay session control server 607 of the network 601. The relay session control server 607 routes to the other carrier IP network 605 described in the NRN information of the redirect message 301, and includes an INVITE message (sip: table) including two numbers, the NRN of the transfer destination carrier and the table number. Number; npdi; rn = NRN @ hostport) is sent to the relay session control server 613 of the other carrier IP network 605, routed in the other carrier IP network 605, and sent to the subscriber terminal 604 of the user who has moved with number portability Incoming call.

  Here, in the above example, the GC 613 corresponds to the number management means, the NRN corresponding to the user table number is searched based on the address management table held by the GC 613, and the destination subscriber terminal 604 is connected. The R-REL message including the NRN of the other carrier IP network 605 is returned to the relay session control server 608 via the IGS 612.

  In this way, the outgoing call from the subscriber terminal 607 of the next-generation IP user is sent to the table number via the subscriber session control server 606 and the relay session control server 607 of the source carrier (company A next-generation network 601). To the destination operator (B company next generation network 602), and in turn to the subscriber session control server 609, the IP telephone service network 610, and the PSTN 603 via the relay session control server 608 of the B company next generation network 602. The INVITE message is sent to resolve the number, and once arrives at the GC 613 in which the subscriber terminal 604 of the user before moving the number portability is accommodated. To the subscriber terminal 604 of the user who has finally moved to the other provider's IP network 605. . In this way, even when a PSTN user moves to another carrier IP network with number portability, a call can be reliably routed.

  Next, a call routing method when a next-generation IP user moves to another provider's IP network with number portability will be described with reference to FIG.

  In FIG. 9, the next generation IP user connected to the A company next generation network 621 is the subscriber terminal 624 of the next generation IP user who was connected to the B company next generation network 622 before moving the number portability from the subscriber terminal 623. Make a call. However, the user of the destination subscriber terminal 624 is moving to the other carrier IP network 625 with number portability and cannot receive a call. Even in this case, in the call routing method and call routing system according to the present embodiment, a call can be routed from the B company next-generation network 622 to the other carrier IP network 625.

  A specific message flow will be described with reference to FIG. The next generation IP subscriber terminal 623 connected to the A company next generation network 621 transmits a call setup request message (INVITE message) to the subscriber session control server 626. The INVITE message to which the Req-URI (table number @ IP-A) is added by the subscriber session control server 626 is sent from the subscriber session control server 626 to the relay session control server (IP-GW) 627, and the relay session control server 627 rewrites the Req-URI of the INVITE message to (table number @ IP-B), and transfers it to the B company next-generation network 622 side to which the subscriber terminal 624 was connected before the movement of the number portability. The INVITE message transferred to the B company next generation network 622 is sent from the relay session control server (IP-GW) 628 to the subscriber session control server 629 in which the subscriber terminal 624 was accommodated before the number portability transfer. However, since the subscriber terminal 624 has moved to the other carrier IP network 625, the subscriber session control server 629 returns the SIP response code redirect message 301 to the relay session control server 628. At this time, the subscriber session control server 629 notifies the message provider's ContactURI of the transfer destination operator in order to notify redirection (movement) due to number portability to the previous operator (sender operator or relay operator). A redirect message 301 describing two numbers, NRN and table number, is returned (sip: table number; npdi; rn = NRN @ hostport). The returned redirect message 301 is returned via the relay session control server 628 to the relay session control server 627 of the company A's next generation network 621 of the transmission source operator. In response to the NRN described in the redirect message 301, the relay session control server 627 sends an INVITE message (sip: table number; npdi; rn = NRN @) that includes two numbers, that is, the NRN and the table number of the transfer destination operator. hostport) is transferred to the relay session control server 630 of the other provider IP network 625. Then, it is routed via the relay session control server 630 in the other provider's IP network 625 and is received by the subscriber terminal 624 of the next-generation IP user who has moved with number portability.

  Here, in the above example, the subscriber session control server 629 corresponds to the number management means, and the NRN corresponding to the user table number is searched based on the address management table held by the subscriber session control server 629. The relay message control server 627 of the next-generation network 621 of the source company A via the relay session control server 628 sends the redirect message 301 including the NRN of the other carrier IP network 625 to which the destination subscriber terminal 624 is connected. Return to

  In this way, even when a user of the next generation network moves to another carrier IP network with number portability, a call can be reliably routed.

  Next, a call routing method when a next-generation IP user moves to the PSTN with number portability will be described with reference to FIG.

  In FIG. 10, the next-generation IP user of the subscriber terminal 642 connected to the next-generation network 641 is the subscriber of the user who was accommodated in the subscriber session control server 643 of the same next-generation network 641 before the movement of number portability. A call is made to the terminal 644. However, since the user accommodated in the subscriber session control server 643 has moved to the PSTN 648 with number portability, it cannot make an incoming call. Even in this case, the call routing method and call routing system according to the present embodiment can route a call from the next generation network 641 to the PSTN 648.

  A specific message flow will be described with reference to FIG. The next generation IP user connected to the next generation network 641 transmits a call setup request message (INVITE message) from the next generation IP subscriber terminal 642 accommodated in the subscriber session control server 645. The INVITE message to which the Req-URI (table number @ IP-A) is added by the subscriber session control server 645 is transmitted from the subscriber session control server 645 to the relay session control server (IP-GW) 646 and the relay session control server (IP -GW, PSTN-GW) 647, and forwarded to subscriber session control server 643 in which next-generation IP users were accommodated before the movement of number portability. However, since the next-generation IP user of the destination has moved to the PSTN 648, the subscriber session control server 643 describes two numbers, the NRN and the table number of the transfer destination operator, in order to notify redirection by number portability. The redirect message 301 is returned to the relay session control server 647 (sip: table number; npdi; rn = NRN @ hostport). The relay session control server 647 routes to the PSTN 648 according to the NRN described in the redirect message 301, and includes an IAM message (called number: NRN, called directory) including two numbers of the NRN and the table number of the transfer destination carrier. ID number: table number) is sent to the GC 650 via the IGS 649 of the PSTN 648, and finally connected to the subscriber terminal 644 of the user who has moved with number portability.

  Here, in the above example, the subscriber session control server 643 corresponds to the number management means, and the NRN corresponding to the table number of the user is searched based on the address management table held by the subscriber session control server 643. The redirect message 301 including the NRN of the other carrier IP network 648 to which the destination subscriber terminal 644 is connected is returned to the relay session control server 647.

  In this way, even when a user of the next generation network 641 moves to the PSTN 648 with number portability, the call can be routed reliably, and the subscriber terminal 642 of the next generation IP user joins the user who has moved to the PSTN 648 with number portability. A call can be made with the user terminal 644.

  As described above with reference to the drawings, the call routing method and call routing system according to the present invention is an integrated communication in which an existing telephone network (PSTN), an IP telephone service network, and a next-generation IP network are integrated. In the network, the load on the relay server can be reduced and the call can be reliably routed to the destination. In particular, even if the user moves from PSTN to the next generation network or IP telephone service network using number portability, or moves under the network management of a different operator, it cannot be connected due to an error as in the prior art. In addition, the call can be reliably routed without imposing a heavy burden on the relay server.

101, 201, 202, 301, 302 ... Integrated communication networks 110, 210a, 210b, 310, 501, 521, 641 ... Next generation network (NGN)
531,601,621 ... A company next generation network 535,602,622 ... B company next generation network 111,211a, 211b, 311a, 311b, 510,533,603,648 ... PSTN
112, 212a, 212b, 312a, 312b, 610... IP telephone service networks 121, 221a, 221b, 321, 502, 503, 504, 506, 552, 523, 538, 542, 548, 606, 609, 613 626,629,630,643,645 ... Subscriber session control server 122,222a, 222b, 322,323,508,509,514,526,539,541,547,607,608,627,628,646 , 647 ... relay session control servers 113, 213a, 213b, 313b, 543, 611 ... linkage servers 114, 214a, 314a, 315a, 505, 507, 511, 524, 525, 532, 534, 536, 601a , 604, 623, 624, 642 644 ... subscriber terminal 141 ... subscriber accommodation server 131,513,545,612,649 ··· IGS
132,512,546,613,650 ... GC
123,544 ... PSTN-GW

“NGS standardization trend of ETSITISPAN” NTT Technical Journal 2006.4 "New communication provided by NGN and the technology that supports it" NTT Technology Journal 2007.4 “Looking at the development of digital exchange for stations”, Vol. 89. No1.2006

Claims (18)

In a call routing method used in an integrated communication network in which a plurality of networks managed independently are integrated,
A transmitting terminal connected to the first network of the plurality of networks transmitting a call setup request message to a subscriber session control server accommodating the transmitting terminal;
The subscriber session control server determines whether or not the destination address of the receiving terminal included in the call setup request message is the accommodating terminal of the subscriber session control server itself. Transferring the request message to the relay server;
The relay server forwards the call setup request message to a number management means without referring to the destination address;
The number management means searches for a logical address corresponding to the destination address based on an address management table held by itself, and returns a redirect message including the logical address and the table number to the relay server;
The call setup request message is transmitted to the terminating subscriber session control server accommodating the terminating terminal connected to any one of the plurality of networks corresponding to the logical address of the redirect message redirected to the relay server. Steps,
Transferring the call setup request message received by the terminating subscriber session control server to the terminating terminal corresponding to the table number. The call routing method according to claim 1, wherein
The relay server, in a case where the destination address is not managed by the number management unit of the first network of the plurality of networks, the step of transferring the call setting request message in order to the number management unit of another network of the plurality of networks A call routing method comprising: The call routing method according to claim 1 or 2,
When routing a call across a plurality of integrated communication networks, the call is transferred from the second integrated communication network to which the call setting request message has been transferred from the first integrated communication network of the transmission source to the third integrated communication network. If so, a call routing method comprising the step of transferring the call setting request message via the first integrated communication network of the caller. In the call routing method according to any one of claims 1 to 3,
The number management means configures the logical address as a transfer destination address (NRN) and sends it back to the relay server when the destination terminal is routed over a user terminal moved by number portability or a plurality of integrated communication networks. A call routing method comprising steps. The call routing method according to claim 4, wherein
The call routing method, wherein the number management means includes a step of returning two numbers of a transfer destination address (NRN) and a table number to the relay session control server. In the call routing method according to any one of claims 1 to 3,
When there are a plurality of subscriber session control servers of a number management source that accommodate the same number band, the plurality of subscriber session control servers of the number management source have a step of expanding the destination address to an SRN. Call routing method. The call routing method according to claim 6, wherein
When a terminal connected to a subscriber session control server that is not a number management source is a calling terminal, the plurality of subscriber session control servers of the number management source send a redirect message including a table number in which the destination address is expanded to an SRN. A call routing method comprising a step of returning to the relay server. The call routing method according to claim 6 or 7,
When the terminal connected to the subscriber session control server of the number management source is a calling terminal, the subscriber session control server to which the calling terminal is connected relays when it cannot connect to the subscriber session control server to which the receiving terminal is connected A call routing method comprising a step of diverting to a server. The call routing method according to any one of claims 1 to 8,
When one of the transfer destination networks is a PSTN, the call setup request message developed in the NRN is converted into an IAM message by the relay server and transferred. An integrated communication network in which multiple networks (next-generation IP network, optical telephone user network, and PSTN) that are managed independently are integrated, including a first network having a subscriber session control server and a relay server. Having a call routing system,
The logical address corresponding to the destination address of the called terminal included in the call setup request message from the calling terminal transferred from the relay server is searched based on the address management table held by itself and includes the logical address and the table number. Providing number management means for creating a redirect message and returning it to the relay server;
The subscriber session control server determines whether or not the destination address of the receiving terminal included in the call setup request message received from the calling terminal accommodated by the subscriber session control server is the own accommodating terminal. Transferring the call setup request message to the relay server;
The relay server transfers the call setting request message to the number management means without referring to the destination address transferred from the subscriber session control server,
The subscriber session control server is an incoming subscriber session control server that accommodates an incoming terminal connected to any one of the plurality of networks corresponding to the logical address of the redirect message redirected to the relay server. The call routing system, wherein the call setup request message is transmitted. The call routing system according to claim 10, wherein
If the relay server has a destination address that is not managed by the number management unit of the first network of the plurality of networks, the relay server sequentially transfers the call setting request message to the number management unit of the other network of the plurality of networks. A call routing system. The call routing system according to claim 10 or 11,
When routing a call across a plurality of integrated communication networks, the relay server of the second integrated communication network to which the call setting request message is transferred from the first integrated communication network of the transmission source Is further transferred to the third integrated communication network, the call setup request message is transferred via the first integrated communication network of the transmission source. The call routing system according to any one of claims 10 to 12,
The number management means configures the logical address as a transfer destination address (NRN) and sends it back to the relay server when the destination terminal is routed over a user terminal moved by number portability or a plurality of integrated communication networks. A call routing system characterized by the above. The call routing system according to claim 13,
The call routing system, wherein the number management means returns two numbers of a transfer destination address (NRN) and a table number to the relay session control server. The call routing system according to any one of claims 10 to 12,
Call routing, wherein when there are a plurality of subscriber session control servers of a number management source accommodating the same number band, the plurality of subscriber session control servers of the number management source expands the destination address in an SRN system. The call routing system according to claim 15, wherein
When a terminal connected to a subscriber session control server that is not a number management source is a calling terminal, the plurality of subscriber session control servers of the number management source send a redirect message including a table number in which the destination address is expanded to an SRN. A call routing system which returns the relay server to the relay server. The call routing system according to claim 15 or 16,
When the terminal connected to the subscriber session control server of the number management source is a calling terminal, the subscriber session control server to which the calling terminal is connected relays when it cannot connect to the subscriber session control server to which the receiving terminal is connected A call routing system comprising a step of diverting to a server. The call routing system according to any one of claims 10 to 17,
When one of the transfer destination networks is a PSTN, the call routing system is characterized in that the call setup request message developed in the NRN is converted into an IAM message by the relay server and transferred.

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