JP5679577B2 - Relay system and relay network codec selection method - Google Patents

Description

  The present invention relates to a relay system and a relay network codec selection method, and more particularly, to a relay network codec selection method and apparatus when a plurality of network operators are straddled.

  More specifically, the present invention relates to a relay system using a mechanism for exchanging capability information in a session establishment process between a terminal and a network in an inter-operator interconnection network, and a codec selection method for a relay network.

  First, a description will be given of a conventional IP (Internet Protocol) technology for a fixed / mobile communication carrier network.

  The Next Generation Network (NGN), which is being discussed at ITU-T, which develops usage related to fixed and mobile communications, assumes a network architecture in which services are provided via IP networks. NGN has decided to adopt the IP Multimedia Subsystem (IMS) established by 3GPP, the standardization organization for third-generation mobile communication networks, and provides network services using this IMS. . IMS is a subsystem that performs service execution control, session control between terminals, registration processing, and billing processing by using SIP (Session Initiation Protocol) (see Non-Patent Document 1) (for example, see Non-Patent Document 2). ).

  In IMS, in the process of control by SIP, a session is established by an offer answer model using SDP (Session Description Protocol). The offer / answer model is defined in Non-Patent Document 3 as a general model for session establishment / update.

  Next, the interconnection between telecommunications carrier networks will be described.

  Non-Patent Document 2 defines NNI (Network Network Interface), which is a signal specification for ensuring interoperability of communication between providers. NNI defines IBCF (Interconnection Border Control Function) as a function to convert signal specification differences between different operators. Further, Non-Patent Document 4 defines an IBGF (Interconnection Border Gateway Function) that converts the difference in specifications of audio media such as codecs in audio communication between operators.

  Next, the connection codec of the communication carrier will be described.

  Since the codec to be used is different for each provider, it is necessary to prescribe the codec to be used for connection in advance between the providers.

  On the other hand, in connection with overseas telecommunications carriers, the amount of communication with each ground is small, and it is not possible to expect profits that are determined by determining connection specifications and individually preparing the devices necessary for connection. In view of this, there is a connection in which a provider (relay operator) that collectively provides connections to a plurality of operators is aggregated in a relay network. As a result, each business operator does not need to install an overseas connection device, and the relay business operator consolidates the connection between each business operator and the overseas, resulting in a large group effect and efficient use of equipment. it can. Here, G.711 is unified with the codec used for relaying to guarantee the connectivity of a plurality of operators.

  Next, a relay network using IP will be described.

GSMA, an industry group of mobile communication carriers and vendors, defines an exchange point (GRX) for exchanging GPRS roaming traffic for IP GSM (registered trademark) and 3G data communication service interworking. . GRX provides connectivity between service providers, end-to-end QoS for roaming and interconnection, and interconnection billing.

  In addition, the following functional requirements are defined as IPX (IP eXchange) in which QoS guarantees, pay-per-use charges, and security functions are superimposed on GRX.

-Interconnection by service-based charging model (selection of charging model according to service);
・ Interworking for specific IP services;
・ Interworking between multiple sites;
There are the following differences in the signal and media specifications in the interconnection with the above other companies.

  Differences in signals include differences in the sequence of SIP signals to be used, method / method header usage, and option usage / non-use. Further, as media differences, there are differences in the codec of audio media, packetization period, bit rate, quality specifications (packet loss rate, delay, jedder) DTMF method, and the like.

  For this reason, a mechanism for absorbing differences in signal and media specifications is necessary for interconnection between telecommunications carriers. In order to absorb this difference, there is a device called SBC (Session Border Controller). As shown in FIG. 1, the SBC can convert a SIP signal and a media signal according to a preset rule.

  By using SBC, each telecommunications carrier interconnects services while maintaining each other's specifications by changing the signal and media according to the specifications of the other party without changing the network specifications. be able to.

  In RFC3264 of Non-Patent Document 3, two endpoints that establish a session called an offer / answer model are an offer side and an answer side, respectively, and include session / media information that is a session proposal established between the two parties from the offer side It is a framework that establishes a session by sending a SDP description document and exchanging a series of messages that return the SDP description document including the session / media information that is answered by the answerer upon receiving the proposal.

  RFC3261 defines rules for exchanging offers / answers using SIP. In the example of FIG. 1, the offer describes the capability supported by the calling terminal and the calling side network, and a plurality of pieces of codec information are written. In addition, the priority of each codec as seen from the transmission provider is expressed by the order in which the codecs are arranged. The answering terminal establishes a session using the codec supported by the receiving terminal and the called network from the capability information on the calling side.

  As shown in FIG. 3, GSMA regulates the use of ENUM in order to solve a signal transfer destination between carriers using a telephone number when interconnecting between carriers. ENUM is a mechanism for obtaining an application corresponding to a telephone number in URI format by searching DNS (Domain Name Service) using the telephone number as a key.

  FIG. 4 shows a number resolution sequence using the carrier ENUM.

  In order to carry out number resolution, the following three steps are necessary.

  Step 1) First, URI conversion is performed from the telephone number. Using the ENUM protocol, the ENUM query FQDN is sent from the SIP server to the ENUM server, and the URI is obtained by ENUM conversion.

  Step 2) Next, query the DNS for the NAPTR record for the domain of the obtained URI, and search for the SRV record. In addition, the SRV record is queried and the corresponding SIP server name and port number are obtained.

  Step 3) Query DNS for A record and obtain the IP address of the corresponding SIP server.

RFC 3261 SIP: Session Initiation Protocol http: //www.left.ora/rfc/rfc3261.txt 3GPP TS 24.229, IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP): Stage 3 http://www.3gpp.org/ftp/Specs/html-info/24229.htm RFC 32264 An Offer / Answer Model with the Session Description Protocol (SDP) http://www.letf.org/rfc/rfc3264.txt ETSI ES 282 001 V3.4.1. "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN): NGN Functional Architecture", Sep. 2009.

  The fixed and mobile networks use different voice codecs, G.711 and AMR, respectively. New voice codecs such as AMR-WB have also appeared. Conventionally, as shown in FIG. 5, in the relay between different codec operators, the codec is unified to G.711 to ensure the interoperability.

  However, as shown in FIG. 6, when the same codec is used between the calling and receiving carriers, there is a case where the codec conversion is not originally required and communication between the carriers can be realized (for example, the codec of the calling carrier). AMR, codec AMR of the callee).

  With the spread of mobile phones, terminals that use AMR have become widespread, and the number of cases where both outgoing and incoming call operators use AMR is increasing. For this reason, in the conventional system, there is a waste of converting and connecting the codec even for communication that does not require the codec conversion, and the wasteful conversion amount tends to increase due to the spread of mobile phones.

  The codec used for communication uses the SIP / SDP offer / answer model. Since the offer / answer system is a mechanism that determines the codec to be used for communication between the two parties (transmission / reception terminal) at the end-end, only the range of the codec supported by the transmission terminal and the operator can be selected. For this reason, as shown in FIG. 7, when a codec with a different origination / termination company uses a codec condition does not match, it cannot communicate.

  For this reason, as shown in FIG. 8, the SBC transmits another offer to the called network. Receiving this, the called network and the receiving terminal send another offer to the called network in which the codec B used by the own network is added or the codec C that cannot be converted by the SBC is deleted. Upon receiving this, the called network and the receiving terminal transmit an answer including the codec B used by the own network to the SBC. Here, since the answer codec (A, C) on the calling side does not match the answer codec (B), the SBC transmits codec A as an answer to the calling side. As a result, communication is established between the calling terminal-originating side network-SBC (codec A) and SBC-destination side network-receiving terminal (codec B), and as a result, communication between the calling terminal is established.

  However, as shown in FIG. 9, there are the following two problems.

  Problem 1) In IPX, since multiple operators are connected, when the offer signal is received by the SBC, it is not possible to determine which codec is being used in the terminating network, so the codec that can be used in the relay network The SBC cannot select the codec necessary to establish communication.

  Problem 2) The relay network needs to be able to control and manage the selection of the relay codec while enabling relay by a plurality of codecs in the relay network.

  The present invention has been made in view of the above points, and a relay system capable of reducing wasteful codec conversion, reducing equipment costs by optimizing equipment, and improving voice connection quality via a relay network, and It is an object to provide a codec selection method for a relay network.

In order to solve the above problems, the present invention (Claim 1) includes a calling side network connected to a calling terminal, a called side network connected to a receiving terminal, and the calling side network and the called side network. A calling-side codec that sets a codec that can be used in the relay network in the relay network and an offer signal and an answer signal transmitted and received in the calling-side network and the called-side network connected to the relay network in the relay network A relay system having a selection device and a destination codec selection device,
The relay network is
Routing information storage means for storing, for each category of connection guarantee level, a domain corresponding to the number of the calling terminal and the called terminal, and a codec that can be used in the calling side network and the called side network. It has an ENUM server that responds to inquiries from the selected device,
The originating codec selection device is:
Means for querying the ENUM server about the domain and codec of the receiving terminal;
Calling side offer signal storage means for holding an offer signal received from the calling side network;
Acquired from the ENUM server or a combination of a codec acquired from a signal transmitted from the calling terminal and a signal transmitted from the transmitting terminal or a codec pre-stored in the codec selection device of the calling side, or acquired from the ENUM server Based on a predetermined rule, a codec described in an offer signal is set based on a predetermined rule for a combination of a receiving codec and a codec acquired from the transmitting terminal , and a domain of the receiving terminal obtained from the ENUM server A calling codec selection means for transmitting as a destination;
Means for converting the codec of the answer signal received from the relay network to the codec of the calling side offer signal storage means if it does not match the codec of the calling side offer signal storage means and sending it to the calling terminal When,
Have
The destination codec selection device is
A destination offer signal storage means for holding an offer signal received from the relay network;
If the codec of the offer signal received from the relay network does not match the codec of the receiving operator, the codec of the receiving operator is converted to the codec of the receiving operator and sent to the receiving terminal, and the answer signal received from the receiving terminal When the codec and the codec of the received offer signal stored in the destination offer signal storage means do not match, the codec selection means for converting to the codec of the offer signal and sending it to the relay network; Have

The present invention (Claim 2) is the routing information storage means of the ENUM server according to Claim 1,
A top first category that includes a codec that the transit network operator ensures connectivity with all outgoing and incoming networks;
A second category lower than the first category including a codec that connects only in the same case between the originating operator and the terminating operator;
Storing the first category, the lowest third category that does not belong to the second category and includes a codec that is not connected, and
The calling codec selection means includes:
Compare the caller's codec A and the callee's codec B obtained from the ENUM server,
If A = B and A is not included in the third category, set A to the offer signal or the answer signal, A = B, and A is in category 3 If included, set the first category codec to the offer signal or the answer signal,
If A ≠ B, and A is not included in the third category, A is set as the relay codec in the offer signal or the answer signal, and A is included in category 3, When B is not included in the third category, the B is set as the offer signal or the answer signal. When B is included in the third category 3, the codec of the first category is set. Is included in the offer signal or the answer signal.

The present invention (Claim 3) includes a calling side network connected to a calling terminal, a called side network connected to a receiving terminal, a calling side network and a relay network connected to the called side network, , A codec selection device on the calling side and a codec selection on the called side that set a codec that can be used in the relay network in an offer signal and an answer signal transmitted / received in the calling side network and the called side network connected to the relay network A codec selection method in a relay system having a device and an ENUM server,
The originating codec selection device is:
Queries the domain of the receiving terminal from the ENUM server
The ENUM server is
Routing information storage means for storing, for each category of connection guarantee level, a domain corresponding to the number of the calling terminal and the called terminal, and a codec that can be used in the calling side network and the called side network. Reply the destination terminal domain and codec corresponding to the inquiry from the device,
The originating codec selection device is:
A first offer information storage means holds an offer signal received from the originating network;
The calling- side codec selection means is for the combination of the receiving side codec acquired from the ENUM server and the codec acquired from the signal transmitted by the transmitting terminal or the combination of the codec previously stored in the calling-side codec selection device, or , For the combination of the receiving side codec acquired from the ENUM server and the codec acquired from the transmitting terminal , on the basis of a predetermined rule, the codec to be described in the offer signal is selected and set on the outgoing side codec selection step;
Sending the offer signal via the relay network to the domain of the receiving terminal acquired from the ENUM server,
The destination codec selection device is
A second offer information storage means holds the offer signal received from the relay network;
If the receiving side codec selection means does not match the codec of the received offer signal with the codec of the receiving operator, the codec of the offer signal is converted to the codec of the receiving operator and transmitted to the receiving terminal,
If the codec of the answer signal received from the receiving terminal does not match the codec of the received offer signal stored in the second offer information storage means, the codec of the offer signal is converted into the codec of the offer signal and sent to the relay network Send
The originating codec selection device is:
If the answer signal received from the relay network does not match the codec of the offer signal stored in the first offer information storage means, it is converted to the codec of the offer signal and transmitted to the originating terminal To do.

Further, the present invention (Claim 4) provides the routing information storage means of the ENUM server according to Claim 3,
A top first category that includes a codec that the transit network operator ensures connectivity with all outgoing and incoming networks;
A second category lower than the first category, including a codec that can be entered, although not essential for connection to the relay network;
Including the first category, the codec that does not belong to the second category, and the lowest third category,
The originating codec selection device is:
Compare the caller's codec A and the callee's codec B obtained from the ENUM server,
If A = B and A is not included in the third category, set A to the offer signal or the answer signal, A = B, and A is in category 3 If included, set the first category codec to the offer signal or the answer signal,
If A ≠ B, and A is not included in the third category, A is set as the relay codec in the offer signal or the answer signal, and A is included in category 3, When B is not included in the third category, the B is set as the offer signal or the answer signal. When B is included in the third category 3, the codec of the first category is set. Is set to the offer signal or the answer signal.

  As described above, according to the present invention, since an appropriate codec can be selected in a network operated by a plurality of codecs, it is not necessary to perform codec conversion for communication that does not require codec conversion as in the conventional method, and a wasteful codec Conversion processing can be reduced. As a result, the equipment cost can be reduced by optimizing the equipment amount, and the voice connection quality via the relay network can be improved.

This is a mechanism for absorbing SBC usage differences among telecommunications carriers. It is a figure which shows the outline | summary of an SDP offer answer. This is a flow of routing processing using ENUM. This is a number resolution sequence using the carrier ENUM. It is a conventional relay network. This is a connection example that does not require codec conversion. This is an example in which communication with the offer answer model is not established. It is a figure which shows absorption of the codec difference using SBC. It is a figure which shows the subject of a prior art. It is a figure which shows the outline | summary of this invention (codec conversion linked with routing information). It is a figure which shows the general process of IP interconnection. It is a functional block diagram of SBC in one embodiment of this invention. It is the acquisition example (the 1) of the codec information using ENUM in one embodiment of this invention. It is the acquisition example (the 2) of the codec information using ENUM in one embodiment of this invention. It is the selection flow of the relay codec based on the codec information of arrival and departure in one embodiment of the present invention. It is a figure which shows the flow of a process of 1st Example of this invention. It is a figure which shows the flow of a process of 2nd Example of this invention. It is a figure which shows the flow of a process of the 3rd Example of this invention. It is a figure which shows the flow of a process of the 4th Example of this invention. It is a figure which shows the flow of a process of the 5th Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 10 shows an overview of the present invention.

  The present invention solves the codec of the relay operator in conjunction with the solution processing of the signal routing destination in the relay network.

  Usually, codecs used for each business operator or number band are often unified. Therefore, the codec corresponding to the operator is mapped one-to-one. Therefore, the present invention cooperates with ENUM and codec resolution to obtain the destination network codec information at the same time as or in conjunction with the destination operator resolution from the destination number, The codec used for the relay is appropriately selected as compared with the codec.

As shown in FIG.
1) Preserve the correspondence between telephone numbers and codecs in each ENUM server in advance.

  2) An inquiry is made about the route information from the originating SBC to the ENUM server of the relay network, and based on the obtained route information, the ENUM server of the called side network is inquired about the codec information of the called side network. The ENUM server of the called side network returns the codec information of the called side network based on the held correspondence.

  3) In the originating SBC, when the codec “A” or “B” is set as the policy of the relay network, the relay codec to be set (for example, “A”) is determined, and the callee side SBC obtained in 2) is determined. Set the domain and send the SIP signal to the relay network.

  4) The relay network relays the offer transmitted from the originating SBC and sends it to the called network specified as the destination. In the destination network, it is converted into the codec of the destination network and transmitted to the receiving terminal. When the destination network receives an answer from the receiving terminal, it transmits a SIP signal obtained by converting the codec to the codec of the relay network (for example, “A”) to the relay network.

First, the general process of IP interconnection will be described.

  FIG. 11 shows the general process of IP interconnection.

  Here, the category is determined in advance by the operator of the relay network in advance as follows, and this system is uniquely determined and stored in the originating SBC and the terminating SBC.

Category 1: Codec for which the relay network operator guarantees connectivity with all outgoing / incoming networks: (For this reason, the SBC of the incoming / outgoing network must have the ability to convert to the codec belonging to this category.)
・ Category 2: Codec that is connected only when the caller and caller are the same: (For this reason, the SBC of the incoming / outgoing network does not require the ability to convert to a codec belonging to this category)
-Category 3: Codec not connected: (The codec belonging to this category is not used for relay connection in the SBC)
Step 101) An INVITE signal (offer signal) including codec information of the calling terminal 100 is transmitted from the calling terminal 100 to the calling SBC 300.

  Step 102) The ENUM 400 is inquired of the destination domain destination domain from the request URI information from the originating SBC 300.

  Step 103) The ENUM server 400 returns the domain of the destination SBC 600 to the destination SBC.

  Step 104) The originating SBC 300 transmits a signal (offer) to the SGC of the domain to which the ENUM server 400 has responded. At this time, the codec of the offer signal is changed to PCMU and the designated codec is changed.

  Step 105) The called side SBC 600 changes the codec (PCMU) of the offer signal to a codec supported by the receiving terminal 200, and transmits an INVITE signal (offer) to the called side network.

  Step 106) If the receiving terminal 200 supports the offered codec, the receiving terminal 200 transmits a 200OK signal (answer signal) describing the codec to the called SBC 600.

  Step 107) The terminating side SBC 600 converts the codec described in the answer signal into PCMU and transmits it to the originating side SBC 300.

Step 108) originating SBC300 transmits to the calling side network is converted into codec utilizing codec written answer signal at the originating network.

  In the present invention, the above-described steps 101 to 104 are expanded to solve the codec information of the destination network in advance, and the codec selection necessary at the time of transmission is performed. The details of the function and processing for performing the processing will be described below.

  The function of the SBC of the present invention will be described below.

  FIG. 12 shows a functional configuration of the SBC in one embodiment of the present invention.

  In the figure, the originating SBC is shown, but the terminating SBC also has the same function.

  The SBC 300 includes a signal routing information reference unit 310, a signal processing unit 320, a relay codec selection unit 330, a registration unit 301, a signal transmission / reception unit 340, a media control unit 350, and a media transmission / reception unit 360 in a database in the ENUM server. The

  The registration unit 301 registers the codec defined in an expanded form of the NAPTR record and SRV record in the routing information storage unit 410 of the ENUM server 400. The information to be registered includes a number band, a domain, and a codec. Among them, the codec registers a plurality of codecs that can be used in the originating network and the terminating network, classified into categories for each connection guarantee level.

  Based on the routing destination resolution request from the signal processing unit 320, the signal routing information reference unit 310 makes an inquiry to the ENUM server 400 for resolving the target carrier of the telephone number that is the destination. Based on the response from the ENUM server 400, the routing processor, SIP, URI, and codec information used by the destination network are transmitted to the signal processing unit 320. This function unit is used only for outgoing calls.

  The signal processing unit 320 has the following functions.

  Dialog information that requires call control is stored in the call control information storage unit 321 from the information described in the SIP signal, and call control is performed.

  ・ Conversion is performed when there is a difference in signal specifications between service providers.

  Edit the information of the SDP section in the SIP signal according to the information from the relay codec selection section 330.

  If there is a difference between the SDP received from the originating network and the SDP received from the destination SBC 600 with respect to the media control unit 350, the media control unit 350 performs a conversion process.

  The relay codec selection unit 330 selects a codec suitable for relay from the use codecs of the calling side network and the called side network.

  The media control unit 350 controls media conversion processing such as codec and packetization period from the signal processing unit 320.

  The media transmission / reception unit 360 performs media conversion processing and transmission / reception of media packets.

  A registration unit (not shown) that defines the codec in the database in the ENUM server registers the number band, domain, and codec in the routing information storage unit 410 of the ENUN server.

  Next, processing of a part surrounded by a dotted frame in FIG. 11 will be described.

<First method>
FIG. 13 is an example (part 1) of acquiring codec information using ENUM according to an embodiment of the present invention.

  In this example, acquisition of codec information along a number resolution sequence when using carrier ENUM will be described.

  In this example, of the following three steps of number resolution, the codec information can be resolved in either step 201 or 202, but in this embodiment, the codec information is returned to the SBC 300 in step 201. .

  It is assumed that the ENUM server 400 holds an SRV record, a SIP server name, a port number, and a NAPTR record in addition to the routing information storage unit 410 shown in FIG.

Step 201) Phone number to URI conversion:
The signal routing information reference unit 310 of the SBC 300 transmits an ENUM inquiry FQDN (Fully Qualified Domain Name) to the ENUM server 400 using the ENUM protocol. The ENUM server 400 refers to the routing information storage unit 410 as shown in FIG. 12 to obtain the URI, and at the same time, in the format of “codec = PCMU” or the like at the end of the SIP URI that responds, And return to SBC300.

Step 202) Convert URI to host (DNS):
The SBC 300 queries the ENUM server 400 for a NAPTR record that associates a domain name and a telephone number with respect to the domain of the obtained URI, and searches for an SRV record. Further, the SRV record is inquired of the ENUM server 400, and the corresponding SIP server name and port number are acquired.

Step 203) Host to IP address conversion:
The SBC 300 inquires the A record for acquiring the IP address from the host name, and acquires the IP address of the corresponding SIP server.

  FIG. 14 is an example (part 2) of acquiring codec information using ENUM according to the embodiment of the present invention.

  In this example, acquisition of codec information along a number resolution sequence when using carrier ENUM will be described.

  In this example, of the following three steps of number resolution, the codec information can be resolved in either step 301 or 302. In this example, the codec information is returned to the SBC 300 in step 301.

  Note that the information held by the ENUM server 400 is the same as in the first embodiment.

Step 301) Phone number to URI conversion (ENUM):
The signal routing information reference unit 310 of the SBC 300 transmits the ENUM inquiry FQDN to the ENUM server 400 using the ENUM protocol .

Step 302) URI to host translation (DNS):
The ENUM server 400 refers to the routing information storage unit 410 as shown in FIG. 12, obtains the SIP URI, appends the codec information of the destination domain in the format such as “codec = PCMU”, Return to SBC300.
The SBC 300 queries the ENUM server 400 for a NAPTR record for the domain of the obtained URI, and searches for the SRV record. Furthermore, the SRV record is inquired, and the corresponding SIP server name and port number, and the codec information of the incoming network domain are acquired.

Step 303) Host to IP address translation (DNS):
The SBC 300 makes an A record inquiry to the ENUM server 400 and acquires the IP address of the corresponding SIP server.

  Next, a method for determining a relay codec will be described.

  The connection policy of the relay network is determined from the codec information of arrival and departure. This policy is determined by determining whether or not the connection is possible from the combination of the codecs of the departure and arrival operators and determining the relay codec.

  FIG. 15 is a relay codec selection flow based on arrival / departure codec information according to an embodiment of the present invention.

  In the example shown in the figure, codecs to be relayed are determined by dividing the codecs into several groups and determining whether or not they belong to the category.

  As an example of categorization, category 1, category 2, and category 3 are in descending order of priority.

・ Category 1: PCMU, AMR
・ Category 2: AMR-WB, PCMA, G.729, G726, EVRC, GSM (registered trademark)
・ Category 3: Other (Do not use relay connection)
In the following description, the originating codec is “A” and the terminating codec is “B”.

  If the originating codec “A” and the destination codec “B” are the same codec (step 401, Yes), it is determined whether the codec “A” (= “B”) is included in the category 3 and included. If so (step 402, No), codec “A” (= “B”) is set as the relay codec (step 403). When the codec “A” (= “B”) is not included in the category 3 (step 402, Yes), the category 1 codec is set in the relay codec (step 404).

  If “A” and “B” are different (step 401, No), it is determined whether “A” is included in category 3 that is not used for relay connection. If not included (step 405, No), “A” is set in the relay codec (step 406). If “A” is included in category 3 (step 405, Yes), it is determined whether “B” is included in category 3, and if not included (step 407, No), “B” is assigned to the relay codec. Is set (step 408). If “B” is included in category 3 (step 407, Yes), the category 1 codec is set in the relay codec (step 409).

  Embodiments of the present invention will be described below with reference to the drawings.

In the following embodiment, the category information stored in the ENUM server 400 is
・ Category 1: PCMU, AMR
・ Category 2: AMR-WB, PCMA, G729, G.726, EVRC, GSM (registered trademark)
・ Category 3: iLBC
Will be described.

[First embodiment]
In the present embodiment, it is assumed that only the category 1 codec PCMU is used in the originating network, and only the category 2 AMR-WB is used in the terminating network.

  FIG. 16 shows a processing flow of the first embodiment of the present invention.

  When the offer signal is transmitted from the origination terminal 100 to the origination side SBC300, the origination side SBC300 stores the offer in a memory (not shown) and includes the destination phone number in the ENUM server 400 and the domain, codec Make an inquiry.

  The ENUM server 400 searches the corresponding destination domain “sip.udp.mnoA.com” and codec “AMR-WB” by referring to the routing information storage unit 410 based on the telephone number acquired from the originating SBC 300. Return to the originating SBC300.

  Since the calling side codec is “PCMU” and the called side codec is “AMR-WB”, the calling side SBC 300 relays by the PCMU along the flow of FIG. An offer with SDP set to codec is generated and sent to the relay network.

  The relay network transmits the offer received from the originating network to the terminating SBC 600. The destination SBC 600 stores the received offer in a memory (not shown), converts the offer codec into the call provider's codec “AMR-WB”, and transmits it to the receiving terminal 200.

  Next, when the receiving side SBC 600 receives an answer in which the provider codec “AMR-WB” is set from the receiving terminal 200, it is different from the offer codec stored in the memory (not shown). And send it to the relay network.

  The SBC 300 that has received the answer from the relay network transmits the offer codec received from the caller terminal 100 to the caller terminal 100 without performing codec conversion because the codec of the answer matches the codec of the answer.

[Second Embodiment]
In this embodiment, a case will be described in which category 2 AMR-WB is used as a codec in both the originating network and the terminating network.

  FIG. 17 shows a processing flow of the second embodiment of the present invention.

  When the offer signal is transmitted from the origination terminal 100 to the origination side SBC300, the origination side SBC300 stores the offer in a memory (not shown) and includes the destination phone number in the ENUM server 400 and the domain, codec Make an inquiry.

  The ENUM server 400 searches the corresponding destination domain “sip.udp.mnoA.com” and codec “AMR-WB” by referring to the routing information storage unit 410 based on the telephone number acquired from the originating SBC 300. Return to the originating SBC300.

  Since the originating side codec is “AMR-WB” and the destination side codec is “AMR-WB”, the calling side SBC 300 performs SDP relaying using “AMR-WB” along the flow of FIG. Generate the set offer and send it to the relay network.

  The relay network transmits the offer received from the originating network to the terminating SBC 600. The destination SBC 600 stores the received offer in a memory (not shown) and transmits it to the receiving terminal 200 while keeping the codec of the offer as it is.

  Next, when the receiving side SBC 600 receives an answer in which the provider codec “AMR-WB” is set from the receiving terminal 200, it is the same as the offer codec stored in the memory (not shown). Send to the relay network without conversion.

  The SBC 300 that has received the answer from the relay network transmits the offer codec received from the caller terminal 100 to the caller terminal 100 without performing codec conversion because the codec of the answer matches the codec of the answer.

[Third embodiment]
In this embodiment, it is assumed that only the category 2 EVRC is used as the codec in the originating network, and only the AMR-WB is used in the terminating network.

  FIG. 18 shows the process flow of the third embodiment of the present invention.

  When the offer signal is transmitted from the origination terminal 100 to the origination side SBC300, the origination side SBC300 stores the offer in a memory (not shown) and includes the destination phone number in the ENUM server 400 and the domain, codec Make an inquiry.

  The ENUM server 400 searches the corresponding destination domain “sip.udp.mnoA.com” and codec “AMR-WB” by referring to the routing information storage unit 410 based on the telephone number acquired from the originating SBC 300. Return to the originating SBC300.

Since the originating side codec is “EVRC” and the terminating side codec is “AMR-WB”, the calling side SBC 300 relays by category 2 “ EVRC ” along the flow of FIG. An offer with SDP set for codec conversion to AMR-WB is generated and sent to the relay network.

  The relay network transmits the offer received from the originating network to the terminating SBC 600. The destination SBC 600 stores the received offer in a memory (not shown), converts the offer codec to the caller's codec “AMR-WB”, and transmits it to the receiving terminal 200.

Next, when the receiving side SBC 600 receives an answer in which the operator codec “AMR-WB” is set from the receiving terminal 200, it differs from the offer codec “ EVRC ” stored in the memory (not shown). Convert to “ EVRC ” and send to relay network.

SBC300 received an answer from the relay network, for transmitting codec offers received from the terminal 100 "EVRC" and answers codec "EVRC" match, and transmits to the transmitting terminal 100 without converting the codec.

[Fourth embodiment]
In the present embodiment, an example in which only the category 1 codec AMR is used on both the calling side and the receiving side will be described.

  FIG. 19 shows a processing flow of the fourth embodiment of the present invention.

  When the offer signal is transmitted from the origination terminal 100 to the origination side SBC300, the origination side SBC300 stores the offer in a memory (not shown) and includes the destination phone number in the ENUM server 400 and the domain, codec Make an inquiry.

  The ENUM server 400 searches the corresponding destination domain “sip.udp.mnoC.com” and the codec “AMR” by referring to the routing information storage unit 410 based on the telephone number acquired from the originating SBC 300, and Return to the side SBC300.

  Since the originating side codec is “AMR” and the terminating side codec is “AMR”, the originating SBC 300 generates an offer to be relayed by AMR along the flow of FIG. 15 and transmits it to the relay network.

  The relay network transmits the offer received from the originating network to the terminating SBC 600. The called SBC 600 stores the received offer in a memory (not shown) and transmits the offer to the receiving terminal 200.

  Next, when the receiving side SBC 600 receives an answer set with the codec “AMR” of the operator from the receiving terminal 200, it is transmitted to the relay network as it matches the offer codec stored in the memory (not shown). To do.

  The SBC 300 that has received the answer from the relay network transmits the offer codec received from the caller terminal 100 to the caller terminal 100 without performing codec conversion because the codec of the answer matches the codec of the answer.

[Fifth embodiment]
In the present embodiment, an example will be described in which the caller uses only category 3 iLBC and the callee uses only category 1 AMR.

  FIG. 20 shows the flow of processing of the fifth embodiment of the present invention.

  When the offer signal is transmitted from the origination terminal 100 to the origination side SBC300, the origination side SBC300 stores the offer in a memory (not shown) and includes the destination phone number in the ENUM server 400 and the domain, codec Make an inquiry.

  The ENUM server 400 searches the corresponding destination domain “sip.udp.mnoC.com” and the codec “AMR” by referring to the routing information storage unit 410 based on the telephone number acquired from the originating SBC 300, and Return to the side SBC300.

  Since the calling side codec is “iLBC” of category 3 and the calling side codec is “AMR”, the calling side SBC 300 is relayed by the calling side category 1 codec “AMR” according to the flow of FIG. Generate an offer to send to the relay network.

  The relay network transmits the offer received from the originating network to the terminating SBC 600. The called SBC 600 stores the received offer in a memory (not shown) and transmits the offer to the receiving terminal 200.

  Next, when the destination SBC 600 receives an answer set with the codec “AMR” of the operator from the receiving terminal 200, it matches the codec of the offer stored in the memory (not shown), so that it directly enters the relay network. Send.

  The SBC 300 that has received the answer from the relay network performs codec conversion to “iLBC” and transmits it to the calling terminal 100 because the offer codec “iLBC” received from the calling terminal 100 does not match the answer codec “AMR”.

  As described above, in the present invention, the database for managing the codec information of the receiver company is arranged in the relay network, and the codec information is stored. As a result, the codec information can be acquired without using the SIP signal. As a result, the codec information can be acquired regardless of the SIP signal of the destination carrier, and an appropriate relay codec can be selected regardless of the connection carrier.

  In addition, in the present invention, a new signal is not used in order to resolve codec information in conjunction with a route resolution process (ENUM) necessary for normal relay connection, instead of newly adding a signal necessary for call connection. Codec information can be acquired without using it. This makes it possible to acquire codec information before an incoming call, which is impossible with the conventional method, without installing a new server or increasing the amount of signal.

  In addition, in order to select a relay codec according to the category classification and apply a policy, in the present invention, it is used by the callee operator in conjunction with the ENUM mechanism used at the time of outgoing call and addressing of the calling SBC. By adding codec information, routing information and codec information are solved at a time. In the present invention, the codec information of the called side and the calling side can be compared at the time of calling from the calling side SBC. The problem can be solved only by cooperation between the originating SBC and the ENUM server. As a result, it is possible to reduce the codec conversion function required for SBC between the relay network and each communication carrier adjacent to the relay network, and it is possible to increase the number of accommodations or save equipment investment.

  By defining a codec that guarantees Category 1 connectivity and defining the connection by the codec for the carrier connected to the relay network, it is possible to connect even when the codec between the calling and receiving carriers does not match . In the present invention, category 1 is selected as long as the calling side arrival side does not match in the codec designated as category 2 by the relay codec selection logic in the calling side SBC. As a result, the outgoing / incoming carrier is converted into a codec designated as category 1 and connected, so that the interoperability with other carriers is guaranteed. Thereby, since it becomes possible to connect with many communication carriers by connecting to the relay network, a highly reliable voice relay can be provided.

  In addition, by defining a codec that does not allow connection as in category 3, it is possible to restrict connection of services that are not provided by the relay network operator. In order to apply this policy, when the codec of category 3 is included in the codec used on the calling side or the called side in the codec selection algorithm, they are not selected as the relay codec. As a result, network use can be limited only to services provided by the relay network operator, making network design and management easier. In addition, it is possible to prevent the relay network from being dirtied due to the use of services that are not originally provided.

  The operation of the constituent elements of the originating SBC and the terminating SBC in the embodiments and examples of the present invention is constructed as a program, installed on a computer used as the originating SBC and the terminating SBC, or executed. It is possible to distribute through a network.

  The present invention is not limited to the above-described embodiments and examples, and various modifications and applications can be made within the scope of the claims.

100 Originating terminal 200 Incoming terminal 300 Originating SBC
301 Codec registration unit 310 Signal routing information reference unit 320 Signal processing unit 321 Call control information storage unit 330 Relay codec selection unit 340 Signal transmission / reception unit 350 Media control unit 360 Media transmission / reception unit 400 ENUM server 500 Relay operator SIP proxy server 600 SBC

Claims (4)

A calling side network connected to the calling terminal, a called side network connected to the called terminal, a relay network connected to the calling side network and the called side network, and the relay network connected to the relay network A relay system having a calling codec selection device and a receiving codec selection device for setting a codec usable in the relay network in an offer signal and an answer signal transmitted / received in a calling side network and a called side network,
The relay network is
Routing information storage means for storing, for each category of connection guarantee level, a domain corresponding to the number of the calling terminal and the called terminal, and a codec that can be used in the calling side network and the called side network. It has an ENUM server that responds to queries from the selected device,
The originating codec selection device is:
Means for querying the ENUM server about the domain and codec of the receiving terminal;
Calling side offer signal storage means for holding an offer signal received from the calling side network;
Acquired from the ENUM server or a combination of a codec acquired from a signal transmitted from the calling terminal and a signal transmitted from the transmitting terminal or a codec pre-stored in the codec selection device of the calling side, or acquired from the ENUM server Based on a predetermined rule, a codec described in an offer signal is set based on a predetermined rule for a combination of a receiving codec and a codec acquired from the transmitting terminal , and a domain of the receiving terminal obtained from the ENUM server A calling codec selection means for transmitting as a destination;
Means for converting the codec of the answer signal received from the relay network to the codec of the calling side offer signal storage means if it does not match the codec of the calling side offer signal storage means and sending it to the calling terminal When,
Have
The destination codec selection device is
A destination offer signal storage means for holding an offer signal received from the relay network;
If the codec of the offer signal received from the relay network does not match the codec of the receiving operator, the codec of the receiving operator is converted to the codec of the receiving operator and sent to the receiving terminal, and the answer signal received from the receiving terminal When the codec and the codec of the received offer signal stored in the destination offer signal storage means do not match, the codec selection means for converting to the codec of the offer signal and sending it to the relay network;
A relay system comprising: The routing information storage means of the ENUM server is
A top first category that includes a codec that the transit network operator ensures connectivity with all outgoing and incoming networks;
A second category lower than the first category including a codec that connects only in the same case between the originating operator and the terminating operator;
Storing the first category, the lowest third category that does not belong to the second category and includes a codec that is not connected, and
The calling codec selection means includes:
Compare the caller's codec A and the callee's codec B obtained from the ENUM server,
If A = B and A is not included in the third category, set A to the offer signal or the answer signal, A = B, and A is in category 3 If included, set the first category codec to the offer signal or the answer signal,
If A ≠ B, and A is not included in the third category, A is set as the relay codec in the offer signal or the answer signal, and A is included in category 3, When B is not included in the third category, the B is set as the offer signal or the answer signal. When B is included in the third category 3, the codec of the first category is set. Means for setting to the offer signal or the answer signal,
The relay system according to claim 1. A calling side network connected to the calling terminal, a called side network connected to the called terminal, a relay network connected to the calling side network and the called side network, and the relay network connected to the relay network A relay having an originating codec selection device, a terminating codec selection device, and an ENUM server for setting a codec usable in the relay network for an offer signal and an answer signal transmitted / received in the originating network and the terminating network A codec selection method in a system,
The originating codec selection device is:
Queries the domain of the receiving terminal from the ENUM server,
The ENUM server is
Routing information storage means for storing, for each category of connection guarantee level, a domain corresponding to the number of the calling terminal and the called terminal, and a codec that can be used in the calling side network and the called side network. Reply the destination terminal domain and codec corresponding to the inquiry from the device,
The originating codec selection device is:
A first offer information storage means holds an offer signal received from the originating network;
The calling- side codec selection means is for the combination of the receiving side codec acquired from the ENUM server and the codec acquired from the signal transmitted by the transmitting terminal or the combination of the codec previously stored in the calling-side codec selection device, or , For the combination of the receiving side codec acquired from the ENUM server and the codec acquired from the transmitting terminal , on the basis of a predetermined rule, the codec to be described in the offer signal is selected and set on the outgoing side codec selection step;
Sending the offer signal via the relay network to the domain of the receiving terminal acquired from the ENUM server,
The destination codec selection device is
A second offer information storage means holds the offer signal received from the relay network;
If the receiving side codec selection means does not match the codec of the received offer signal with the codec of the receiving operator, the codec of the offer signal is converted to the codec of the receiving operator and transmitted to the receiving terminal,
If the codec of the answer signal received from the receiving terminal does not match the codec of the received offer signal stored in the second offer information storage means, the codec of the offer signal is converted into the codec of the offer signal and sent to the relay network Send
The originating codec selection device is:
If the answer signal received from the relay network does not match the codec of the offer signal stored in the first offer information storage means, it is converted to the codec of the offer signal and transmitted to the originating terminal A codec selection method for a relay network. In the routing information storage means of the ENUM server,
A top first category that includes a codec that the transit network operator ensures connectivity with all outgoing and incoming networks;
A second category lower than the first category, including a codec that can be entered, although not essential for connection to the relay network;
Including the first category, the codec that does not belong to the second category, and the lowest third category,
The originating codec selection device is:
Compare the caller's codec A and the callee's codec B obtained from the ENUM server,
If A = B and A is not included in the third category, set A to the offer signal or the answer signal, A = B, and A is in category 3 If included, set the first category codec to the offer signal or the answer signal,
If A ≠ B, and A is not included in the third category, A is set as the relay codec in the offer signal or the answer signal, and A is included in category 3, When B is not included in the third category, the B is set as the offer signal or the answer signal. When B is included in the third category 3, the codec of the first category is set. 4. The codec selection method for a relay network according to claim 3, wherein: is set in the offer signal or the answer signal.

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