JP2013012855A - Relay system, and codec selection method for relay network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent useless codec conversion of codecs utilized by call originating and call incoming carriers.SOLUTION: In advance, a codec policy sets three categories: guaranteeing connectability; connecting only when codecs of call originating and call incoming carriers are the same; and not connecting. A SBC(SBC) on the call originating side offers codecs of guaranteeing connectability and connecting only when the codecs of the call originating and call incoming carriers are the same. A SBC(SBC) on call incoming side determines a relay codec by comparing the offer with a codec of a call incoming side network. In determining the codec; the SBC(SBC) on call incoming side sets a codec included in a category having higher priority according to the priority, and performs codec conversion when there is a difference between codecs in the offer and an answer.

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 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;
RFC3264 shown in Non-Patent Document 3 above is a session established between the two parties from the offer side, as shown in Fig. 1, in which the two endpoints that establish the offer / answer model session are the offer side and the answer side, respectively. A frame that establishes a session by sending a SDP description document that includes session / media information that is a proposal, and that receives the proposal and returns an SDP description document that includes the session / media information that is the answer. Work. RFC3264 defines a rule 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.

  There are the following differences in signal and media specifications for interconnection between other operators.

  Differences in signals include differences in the sequence of SIP signals to be used, methods, usage methods of headers, use of options, and the like.

  Further, as media differences, there are audio media codecs, packetization periods, bit rates, quality specifications (packet loss rate, delay, jedder), DTMF methods, and the like.

  For this reason, interconnection between telecommunications carriers requires a mechanism for interpreting differences in signal / media specifications and converting the specifications to each other, which is called SBC (Session Border Controller). A device for converting a SIP signal and a media signal as shown is used.

  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.

  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, in a relay between operators using different codecs, as shown in FIG. 3, the codec is unified to G.711 to ensure the interoperability.

  However, as shown in FIG. 4, when the same codec is used between operators or between outgoing and incoming carriers, there is a case where inter-provider communication can be realized without originally requiring codec conversion. In addition, with the spread of mobile phones, terminals that use AMR have become popular, and the number of cases where both calling and receiving operators use AMR has increased. For this reason, it can be said that the conventional method has a waste of converting and connecting the codec even for the communication which does not require the codec conversion, and the wasteful conversion amount tends to increase due to the spread of the mobile phone.

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.

  As described above, the object of the present invention is to reduce wasteful codec conversion, reduce equipment cost by optimizing equipment quantity, and improve voice connection quality via a relay network. Therefore, communication that does not require codec conversion between calling and receiving operators must be able to be connected without converting the codec, and communication that requires codec conversion must be possible with a minimum number of codec conversions. is there.

  The SIP / SDP offer answer model is used to determine the codec used in communication. The offer answer method is a mechanism in which the codec to be used for communication between two parties (calling and receiving terminals) is determined at the end-end, and therefore, as shown in FIG. 5, the codec (A , B) and the caller can support the codec specified on the caller side, communication is established, but if there is no codec to support on the callee side, the answerer has no codec information. Communication is not established. In other words, it can be selected only within the range of the codec supported by the calling terminal / operator. For this reason, when a codec with a different calling / incoming carrier is used, communication cannot be performed because the codec conditions do not match.

  To deal with this, SBC modifies the SDP offer generated by the calling terminal, adds codec B that can be converted by SBC, or deletes codec C that cannot be converted by SBC. Send. Receiving this, the called network and the terminal send an answer including the codec B used by the own network to the SBC. For example, as shown in FIG. 6, 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 and the calling side network to the calling side SBC (codec A), and between the called side SBC and the called terminal and the called side network (codec B), and as a result, communication between the calling and receiving terminals is established.

  The prior art has the following two problems as shown in FIG.

  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 in order to select a relay codec so as not to perform useless codec conversion from the codec used by the calling and receiving carriers, in the process of the SIP offer answer model, Compare the codec information of the departure and arrival from the codec information described in the SDP in the SIP signal at the originating gateway (hereinafter referred to as “SBC”) and the destination SBC, and apply SDP as appropriate to apply the relay policy in the relay network. It is an object of the present invention to provide a relay system using SIP / SDP and a codec selection method for a relay network that can add and delete codecs.

In order to solve the above problems, the present invention (Claim 1) includes a calling side network connected to a calling side terminal, a called side network connected to a called side terminal, and a connection to the calling side network and the called side network. And an originating side that sets a codec that can be used in the relay network in an offer signal and an answer signal transmitted and received in the originating network and the terminating network connected to the relay network in the relay network A relay system having a codec selection device and a codec selection device on the called side,
The originating codec selection device is:
Means for holding an offer signal received from the originating network;
A caller codec correspondence table storage means storing a combination of codecs used by a caller of the caller network;
Referring to the caller codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set, and the priority of the codec is changed according to the connection guarantee level of the codec category. Side codec setting means,
The destination codec selection device is
Means for holding an offer signal received from the relay network;
A receiver codec correspondence table storing means for storing a combination of codecs used by the receiver of the destination network;
Referring to the callee codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set as required, and the priority of the codec is set according to the connection guarantee level of the category of the codec. A destination codec setting unit for changing the rank;

The present invention (claim 2) includes a calling side network connected to a calling side terminal, a called side network connected to a called side terminal, a relay network connected to the calling side network and the called side network, and the relay In the network, the codec selection device on the calling side and the codec selection device on the called side that sets the codec that can be used in the relay network in the offer signal and the answer signal transmitted and received in the calling side network and the called side network connected to the relay network A relay system having a codec selection device,
The relay network is
Routing information storage means storing a domain corresponding to the number of the calling terminal and the called terminal, and an ENUM server that responds to an inquiry from the calling codec selection device,
The originating codec selection device is:
Means for querying the ENUM server for the domain of the receiving terminal;
Means for holding an offer signal received from the originating network;
Caller codec correspondence table storage means that sets the codec used by the caller of the caller network for each level of connection guarantee;
Referring to the caller codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set, and the priority of the codec is changed according to the connection guarantee level of the codec category. Side codec setting means,
Means for transmitting the offer signal to the domain of the receiving terminal obtained from the ENUM server;
Have
The destination codec selection device is
Means for holding an offer signal received from the relay network;
A receiver codec correspondence table storage means for setting the codec used by the receiver of the called network for each connection guarantee level;
Referring to the callee codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set as required, and the priority of the codec is set according to the connection guarantee level of the category of the codec. And a destination-side codec setting means for changing the rank.

The present invention (Claim 3) is the relay system according to Claims 1 and 2,
The sender codec correspondence table storage means and the receiver codec correspondence table storage means are:
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 setting means of the calling codec selection device is:
The offer signal including the codec of the first category is transmitted to the relay network, and the codec of the offer signal received from the originating network is referred to the third category with reference to the caller codec correspondence table storage unit. Means for raising the priority of the codec of the received offer signal,
Means for converting the codec if there is a difference between the answer signal received from the relay network and the offer signal received from the originating network that is held;
Including
The destination side codec rank determining means of the destination side codec selector is:
Means for adding the codec of the destination network to the end of the offer signal and transmitting it to the destination network if the codec of the offer network received from the relay network does not include the codec of the destination network; ,
Based on the codec of the answer signal received from the destination network and the codec of the offer signal received from the relay network that is held, the codec to be set from the callee codec correspondence table storage means is selected and an answer signal is generated And means for transmitting to the relay network.

The present invention (Claim 4) includes a calling side network connected to a calling side terminal, a called side network connected to a called side terminal, a relay network connected to the calling side network and the called side network, and the relay In the network, the codec selection device on the calling side and the codec selection device on the called side that sets the codec that can be used in the relay network in the offer signal and the answer signal transmitted and received in the calling side network and the called side network connected to the relay network A codec selection method for a relay network in a relay system having a codec selection device,
The originating codec selection device is:
A first offer information storage means holds an offer signal received from the originating network;
The calling codec setting means refers to the calling codec correspondence table storage means in which combinations of a plurality of codecs used by the calling network provider of the calling network are stored for each connection guarantee level, and offers as needed. Selecting and setting the codec to be described in the signal and the answer signal, and changing the priority of the codec according to the connection guarantee level of the category of the codec,
The destination codec selection device is
A second offer information storage means holds the offer signal received from the relay network;
The called side codec setting means refers to the called codec correspondence table storage means in which combinations of a plurality of codecs used by the called party of the called side network are stored for each connection guarantee level, and the offer signal and the answer signal Are selected and set, and the priority of the codec is changed according to the connection guarantee level of the category of the codec.

The present invention (Claim 5) includes a calling side network connected to a calling side terminal, a called side network connected to a called side terminal, the calling side network and a relay network connected to the called side network, and the relay In the network, the codec selection device on the calling side and the codec selection device on the called side that sets the codec that can be used in the relay network in the offer signal and the answer signal transmitted and 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 codec selection device and an ENUM server,
The ENUM server is
Routing information storage means storing domains corresponding to the numbers of the calling terminal and the called terminal;
The originating codec selection device is:
Queries the domain of the receiving terminal from the ENUM server,
The ENUM server is
Responding to the domain of the receiving terminal corresponding to the inquiry from the calling codec device,
The originating codec selection device is:
A first offer information storage means holds an offer signal received from the originating network;
The caller codec setting means refers to the caller codec correspondence table storage means in which combinations of a plurality of codecs used by the caller of the caller network are stored for each connection guarantee level, and the offer signal and the answer signal The codec described in the above is selected and set, and the priority of the codec is changed according to the connection guarantee level of the category of the codec.
Send an offer signal to the domain of the called terminal obtained 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;
The called side codec setting means refers to the called codec correspondence table storage means in which combinations of a plurality of codecs used by the called party of the called side network are stored for each connection guarantee level, and the offer signal and the answer signal Are selected and set, and the priority of the codec is changed according to the connection guarantee level of the category of the codec.

Further, the present invention (Claim 6) is a codec selection method for a relay network according to Claims 4 and 5,
The sender codec correspondence table storage means and the receiver codec correspondence table storage means are:
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;
Storing the first category, a codec that does not belong to the second category, and the lowest third category;
The originating codec selection device is:
The offer signal including the codec of the first category is transmitted to the relay network, and the codec of the offer signal received from the originating network is referred to the third category with reference to the caller codec correspondence table storage unit. If it is not included, the codec priority of the received offer signal is increased and transmitted,
If there is a difference between the answer signal received from the relay network and the held offer signal received from the originating network, the codec is converted and transmitted to the originating network,
The destination codec selection device is
When the codec of the offer side received from the relay network does not include the codec of the destination side network, the codec of the destination side network is added to the end of the offer signal and transmitted to the destination side network,
Based on the codec of the answer signal received from the destination network and the codec of the offer signal received from the relay network that is held, the codec to be set from the callee codec correspondence table storage means is selected and an answer signal is generated To the relay network.

  As described above, according to the present invention, since an appropriate codec can be selected in a network operated by a plurality of codecs, there is no need to perform codec conversion for communication that does not require codec conversion as in the conventional method, and 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.

It is a figure which shows the outline | summary of an SDP offer answer. It is a mechanism for absorption of usage differences of the telecom operator Mano SBC. It is an example of the 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 the existing technology. It is a figure for demonstrating the outline | summary of this invention. It is a figure which shows the characteristic of this invention. It is a figure which shows the flow of the relay network connection using SIP between general providers. It is a functional block diagram of SBC in one embodiment of the present invention. It is a figure which shows the flow of the process in one embodiment of this invention. It is an example of the flow of the process which considered the codec selection policy of the relay provider in one embodiment of this 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. It is a figure which shows the effect of this invention.

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

  FIG. 8 shows an overview of the present invention, and FIG. 9 shows features of the present invention.

  The present invention compares the codec information of the arrival and departure from the codec information described in the SDP in the SIP signal between the originating SBC and the terminating SBC in the process of the SIP offer answer model, and applies the relay policy in the relay network. As described above, this is a signaling method using SIP / SDP in which codecs are added to and deleted from SDP as appropriate.

  The outline of the present invention will be described with reference to FIGS.

  1. When the offer signal is sent from the calling terminal 100, the calling SBC converts the offer signal according to the policy of the relay network. In the relay network, multiple codecs used in IPX are set. At this time, the offer exchanged in IPX is sent by prioritizing the codecs in the range specified by the relay operator for use in IPX. In the example of FIG. 8, the codec “B” is added in accordance with the relay network policy (codecs A and B are guaranteed to be connected) by the originating SBC in the offer side codec “A” offer. At this time, it adds according to the priority of the codec.

  2. In the destination side SBC, the codec of the destination side network is added to the designated codec of the originating side network and the relay network as necessary. In the example of FIG. 8, “C” is added as the codec of the destination network.

  3. The destination SBC determines the relay codec. In the example of FIG. 8, the codec is determined as “A”.

  4). When the destination SBC obtains an answer from the destination network, it performs codec conversion in accordance with the relay codec. In the example of FIG. 8, the codec “C” on the called side network is converted to the codec “A” on the calling side network, and is sent to the calling side network.

  As shown in FIG. 9, at the originating SBC of the relay network, an offer to be exchanged within IPX is sent by prioritizing a plurality of codecs within the range specified by the relay operator for use within IPX, and at the terminating SBC The codec supported by the destination network and the terminal is added as necessary.

  FIG. 10 shows a flow of relay network connection using SIP between general business operators. The following description is based on the premise of a system including the calling terminal 100, the calling SBC 300, the ENUM server 400, the relay operator SIP proxy server 500, the called SBC 600, and the receiving terminal 200. The ENUM server 400 includes a routing information storage unit 410 that stores a domain associated with the called number band. The originating network uses only PCMA, and the terminating network uses only AMR-WB.

  The correspondence between categories and codecs managed by the relay network is as follows.

・ Category 1 (Connectivity guarantee)
PCMU, AMR
・ Category 2 (Connected only when the caller and caller are the same)
AMR-WB, PCMA, G.729, G.726, EVRC, GSM
・ Category 3 (not connected)
iLBC
Step 101) An INVITE signal (offer) including codec information of the calling terminal 100 is transmitted from the calling terminal 100 to the calling SBC 300. At this time, the offer is associated with “PCMA” of category 2 as a codec.

  Step 102) The originating SBC 300 inquires the ENUM server 400 about the incoming domain based on the information of the Request URI.

  Step 103) The ENUM server 400 refers to the routing storage unit 410 and returns the address information of the called SBC 500 to the calling SBC 300.

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

  Step 105) The destination SBC 500 changes the signal specified by the PCMU to a codec supported by the destination terminal 200. Here, the AMR-WB of category 2 is set, and an INVITE signal (offer) is transmitted to the destination network.

  Step 106) If the called terminal 200 supports the offered codec (AMR-WB), the called terminal 200 transmits an answer describing the codec to the called SBC 600.

  Step 107) The terminating SBC 600 converts the codec (AMR-WB) described in the answer into PCMU and transmits it to the originating SBC 300.

  Step 108) The calling side SBC 300 converts the codec (PCMU) described in the answer into PCMA used in the calling side network and transmits it to the calling side network.

  The present invention is applied to session establishment processing using SIP / SDP other than steps 102 and 103 among steps 101 to 108 described above, and performs codec selection to be used in the relay network along the process of outgoing / incoming processing. Is.

  Next, the SBCs 300 and 600 on the originating side and the receiving side will be described.

  FIG. 11 is a functional block diagram of the SBC in one embodiment of the present invention.

  Both SBCs 300 and 600 have the same configuration. In addition, the SIP server 500 of the relay network has a routing information storage unit 410 that holds a telephone number band and a domain in association with each other. The telephone number and domain of the contents of the routing information storage unit 410 can be updated at any time.

  Each SBC 300, 600 includes signal routing information reference units 310, 610, signal processing units 320, 620, relay codec selection units 330, 630, signal transmission / reception units 340, 640, media control units 350, 650, media transmission / reception units 360, 660. Consists of

  Based on the routing destination resolution request from the signal processing unit 320, the signal routing information reference unit 310 refers to the routing information storage unit 410 of the ENUM server 400 and acquires the domain of the target business operator that is the destination. Based on the acquired response from the ENUM server 400, the routing processor and the SIP URI are transmitted to the signal processing unit 320. Since the signal routing information reference unit 310 is used only at the time of transmission, the signal routing information reference unit 610 on the receiving side is not described above.

  The signal processing units 340 and 640 have the following functions.

  Dialog information necessary for call control is stored in the call control information storage units 321 and 621 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 sections 330 and 630.

  If there is a difference between the SDP received from the calling side network and the SDP received from the called side SBC, the media control unit 350 is instructed to perform conversion processing.

  The relay codec selection units 330 and 630 have category-codec format codec tables 331 and 631 on the relay network, and the codec suitable for the relay from the use codec of the originating network and the destination network with reference to the table. Select. Although this embodiment is described as having a codec table in the relay codec selection units 330 and 630 in the originating SBC 300 and the destination SBC 600, the present embodiment is held in the SBC or a server in the relay network. You may make it refer.

  Media control units 350 and 450 control media conversion processing such as codecs and packetization periods from the signal processing units 320 and 620.

  The media transmission / reception units 360 and 460 perform media conversion processing and transmission / reception of media packets according to instructions from the media controls 350 and 650.

  Next, the processing of the relay codecs 330 and 630 will be described.

  FIG. 12 is a diagram showing a flow of processing in one embodiment of the present invention.

  It is assumed that the originating SBC 300 and the terminating SBC 600 have a memory in which codecs that can be used by the originating terminal 100 and the terminating terminal 200 are stored.

  1) First, when the relay codec selection unit 330 of the originating SBC 300 receives the SDP (offer) “O1” from the originating network via the signal processing unit 320, the offer “O1” is stored in a memory (not shown). ), Refer to the category-codec correspondence table on the relay network, add all the codecs available in IPX to the SDP, generate a new offer "O2", and send it to the destination SBC600 To do.

  2) Next, the destination SBC 600 stores the offer “O 2” in a memory (not shown) in the signal processing unit 620 and refers to the category-codec correspondence table in the relay codec selection unit 630. The codec supported by the side network is additionally set to “O2” and transmitted to the destination side SBC 600.

  3) Thereafter, when receiving the answer “A1” from the called terminal 200 via the called network, the called SBC 600 receives the answer “A1” in the received offer “O2” stored in the memory (not shown). If it is included, the answer “A2” is set to the answer “A2” to be exchanged within the IPX, and the answer “A2” is set via the signal processing unit 620 to the originating SBC 300. Send to. If the offer “O2” does not include the codec of the answer “A1”, the topmost (category 1) codec in the “O2” is set to the codec of the answer “A2”, and the answer “A2” is set to the signal processing unit 620. Is sent to the originating SBC 300 and the media control unit 650 is instructed to convert the codec and the codec of the answer “A2”. As a result, the media transmission / reception unit 360 performs codec conversion according to an instruction from the media control unit 350.

  4) Upon receiving the answer “A2”, the originating SBC 300 checks whether the offer “O1” stored in the memory (not shown) matches the codec of the answer “A2”. The control unit 350 is instructed to convert the answer “A2” codec to the offer “O1” codec, and transmits the offer “O1” to the originating network as the answer “A3”.

  In addition to the above processing, by adding multiple codes to the SDP (offer answer) in the SBC 300 that the relay operator has specified for use within IPX, the relay operator manages and controls the relay codec. Even if the side codec is unknown, it is possible to relay between communication carriers.

  Next, in FIG. 12, the details of the codec setting method included in the offer generation at the originating SBC 300 are shown.

  An example will be described in which a codec selection policy for performing categorization is taken into account when additionally setting a relay codec designated by the relay operator in the originating SBC 300.

  FIG. 13 is an example of the flow of processing that takes into account the codec selection policy of the relay operator in an embodiment of the present invention.

  For example, the codec is divided into the following categories 1 to 3 and the codec is additionally set in the processing flow within the thick line frame shown in FIG. 13 to reflect the connectivity guarantee level and relay policy by relay for each codec. be able to. The priorities are category 1> category 2> category 3.

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)
The above-mentioned category is determined in advance by the operator of the relay network, and this system is uniquely determined.

  Since each of the arrival and departure networks SBC 300 and 600 can be connected to the relay network for the communication of the codec belonging to category 1, at least the media conversion function between the codec supported in the own network and the codec belonging to category 1 is provided in the media transmission / reception unit 360, 660.

In the example of FIG.
・ Category 1 (C1): PCMU, AMR;
・ Category 2 (C2): AMR-WB, PCMA, G.729, G.725, EVRC, GSM;
・ Category 3 (C3): Others;
And

  When the relay codec selection unit 330 of the originating SBC 300 receives the offer “O1” from the originating network, the offer “O1” is stored in a storage means such as a memory, and the codec of the offer “O1” is assigned to the category “C1”. If it is included, the codec of “O1” is set as the head, then all the remaining codecs of the category “C1” are set to “O2” and transmitted to the relay network. If the codec of the offer “O1” is not included in the category “C1”, it is determined whether the codec of the “O1” is included in the category “C2”. If included, the codec of the category “C1” is included. Next, the offer “O2” set in the order of the codecs included in the offer “O1” is transmitted to the relay network. If not included, an offer “O2” in which all codecs of the category “C1” are set is transmitted. If offer "O1" contains multiple codecs (O1-A, O1-B), select logic is applied to each of "O1-A" and "O1-B", and the logical sum Is the offer "O2". The subsequent processing is the same as in FIG.

  As a result, the relay network operator can manage and control the relay codec more finely.

In the examples below,
・ Category 1: PCMU, AMR
・ Category 2: AMR-WB, PCMA, G.729, G726
・ Category 3: iLBC
Will be described as being stored in the relay codec selection units 330 and 630 of the originating SBC 300 and the terminating SBC 600. By setting a rule that requires connection by a codec belonging to the category of the codec regarding the guarantee of connectivity as shown in the above example, a session by the codec belonging to the category can be established by the SDP offer answerer.

[First embodiment]
In the present embodiment, a case will be described in which the originating codec belongs to “category 1” and the called codec belongs to “category 2”.

  FIG. 14 is a diagram showing a processing flow of the first embodiment of the present invention.

  Assume that the originating network uses only PCMU (category 1) and the terminating network uses only AMR-WB (category 2).

  Upon receiving the offer “a = rtpmap: 0 PCMU / 8000” from the originating network, the originating SBC 300 stores the offer in the memory in the originating SBC 300, the category of the codec is category 1, and the relay network Referring to the category-codec codec table 331, another codec “a = arpmap: 97 AMR / 8000” included in category 1 is added to the offer.

  When the destination SBC 600 receives the above offer through the SIP proxy server 500 of the relay operator, the offer is stored in the memory, and the offerer's codec (AMR-WB) is not included in the offer. Then, “a = rtpmap: 97 AMR-WB / 16000” in which the codec of the callee operator is set by the media transmission / reception unit 660 is transmitted to the callee network via the media control unit 650.

  When the receiving side SBC 600 receives the answer “a = rtpmap: 97 AMR-WB/16000” via the called side network, the offer “a = arpmap: 97 AMR / 8000” received from the calling side stored in the memory. Therefore, the codec is converted into “a = RTPMAP: 97PCMU / 8000” by the media transmission / reception unit 660 via the media control unit 650 and transmitted to the originating SBC 300 via the SIP proxy server 500.

  Since the codec matches between the offer and the answer stored in the internal memory, the calling side SBC 300 transmits the codec (PCMU) to the calling side network without converting it.

  Thus, the connection is guaranteed by setting the codec (category 1) essential for connection as the highest priority and converting the codec of the callee user to category 1.

[Second embodiment]
In the present embodiment, an example in which the codec belonging to “Category 1” is used by the transmitting companies in a consistent manner is shown.

  FIG. 15 is a diagram showing the flow of processing in the second embodiment of the present invention.

  A case where only the codec “AMR-WB” of category 1 is used for both the originating network and the terminating network will be described.

  The calling side SBC 300 refers to the codec table 331, and since the category of the calling side codec (AMR-MB) is “2”, the offer “a = rtpmap: 0 AMR-WB/16000” ends (lowest) And add the codec “a = rtpmap: 0 PCMU / 8000” and “a = rtpmap: 96 AMR / 8000” belonging to category 1 above the received offer, and the offer via the SIP proxy server 500 To the destination SBC 600. The destination SBC 600 stores the offer in a memory and sends it to the destination network.

  When the destination SBC 600 obtains the answer “a = rtpmap: 97 AMR-WB / 16000” from the destination network, the offer matches the answer, so the codec is not converted and the calling side is sent via the SIP proxy server 500. Send to SBC300.

  When the originating SBC 300 receives the answer, the codec matches between the offer and the answer, so the codec is not converted.

  In this way, when the originating and terminating codecs are the same, neither the originating SBC 300 nor the terminating SBC 600 is converted.

[Third embodiment]
In the present embodiment, an example is shown in which the codec belonging to “Category 2” does not match the codec of the outgoing / incoming carrier.

  FIG. 16 is a diagram showing a processing flow of the third embodiment of the present invention.

  A case will be described where only the EVRC (category 2) is used in the originating network, and only AMR-WB (category 2) is used in the terminating network. That is, this is an example where the categories match but the codecs do not match.

  When the originating SBC 300 receives an offer including “a = rtpmap: 96 EVRC / 8000” from the originating network, the codec “a = rtpmap: 0PCMU / 8000” and “a = rtpmap: 96 AMR / 8000 "is added, and if the originating codec relay category is" 2 ", the above" a = rtpmap: 96 EVRC / 8000 "is set at the end.

  When the receiving side SBC 600 receives the offer, the offer is stored in the memory, and the codec “a = rtpmap: 98 AMR-WB / 16000” of the receiving carrier is set and transmitted to the receiving side network.

  Next, the answer “a = rtpmap: 98 AMR-WB / 16000” received from the destination network by the destination SBC 600 and the offer “a = rtpmap: 0PCMU / 8000”, “a = rtpmap: 96” Since it does not match any codec of AMR / 8000 "," a = rtpmap: 96 EVRC / 8000 ", the codec table 631 is referred to and the codec" a = rtpmap: 0 PCMU / 8000 "of the highest category 1 is referred to Then, the answer is sent to the originating SBC 300.

  Since the codec does not match between the offer “a = rtpmap: 96 EVRC / 8000” and the received answer “a = rtpmap: 0 PCMU / 8000”, the calling side SBC 300 receives the codec “a = rtpmap: 96 EVRC / 8000”. = rtpmap: 96 Convert to EVRC / 8000 "and send to the originating network.

  As described above, the calling SBC 300 changes the codec priority from the category of the codec information specified by the offer generated in the calling network, adds the codec of category 1 and rearranges it, and sends it to the called SBC. Send. Next, the destination SBC also transmits the offer with priority given again by adding the codec of the destination network to the destination terminal 200. By the above prioritization, it is possible to avoid the occurrence of useless codec conversion in the end by performing codec selection according to each category.

[Fourth embodiment]
In this embodiment, a case will be described in which both the calling and receiving carriers use a codec (AMR) belonging to category 1.

  FIG. 17 is a diagram showing a processing flow of the fourth embodiment of the present invention.

  When the originating SBC 300 receives an offer including “a = rtpmap: 96 AMR / 8000” from the originating network, the codec table 331 is referred to and another codec belonging to category 1 “a = rtpmap: 0 PCMU / 8000”. Is added to the end and sent to the destination network. Upon receiving the offer, the terminating SBC 600 stores the offer in memory and converts the offer “a = rtpmap: 96 AMR / 8000”, “a = rtpmap: 0 PCMU / 8000” without converting the codec. Is sent to the destination network.

  The receiving terminal 200 transmits “a = rtpmap: 96 AMR / 8000” as an answer to the called SBC 600. The receiving side SBC 600 matches the codec between the offer stored in the memory and the received answer. The originating SBC 300 that has received the answer from the SIP proxy server 500 does not perform codec conversion and sends it to the destination network because the offer and the answer match.

  Thus, it is not necessary to perform useless codec conversion at the time of answer transmission.

[Fifth embodiment]
In the present embodiment, a case where a transmission company inputs a codec belonging to category 3 will be described.

  It is assumed that only the Category 3 iLBC is used in the originating network, and only the Category 1 AMR is used in the terminating network. Note that the iLBC is a service that is not provided by the relay network operator.

  When the originating SBC 300 receives an offer including “a = rtpmap: 96 iLBC / 8000” of category 3 from the originating network, the codec table 331 is referenced to delete the codec iLBC of category 3 and change to category 1 Add the codec "a = rtpmap: 96 AMR / 8000" and "a = rtpmap: 0 PCMU / 8000" to which it belongs and send it to the destination network. Upon receiving the offer, the destination SBC 600 stores the offer in a memory and sends “a = trpmap: 96: AMR / 8000” in which the codec AMR of the destination operator is set to the destination network as an offer. .

The receiving terminal 200 sends an answer including “a = rtpmap: 96 AMR / 8000” to the destination SBC 600. The destination SBC 600 matches the offer stored in the memory with the codec of the received answer, and does not perform codec conversion, and sends it to the SIP proxy server 500. The originating SBC 300 that has received the answer from the SIP proxy server 500 converts the codec and sends it to the originating network because the offer and answer do not match.
As described above, the category 3 codec is controlled not to be described in the SDP in the offer / answer information conversion logic in the originating SBC 300 and the terminating SBC 600.
For this reason, even if a session can be established with a category 3 codec between the departure and arrival operators, it is possible to control the codec on both sides by converting the category of the relay operator.
FIG. 19 shows the effect of the present invention. FIG. 2A shows a conventional relay network, and FIG. 2B shows the relay network of the present invention. Conventionally, as shown in FIG. 5A, codec conversion is performed even with the same codec, but conversion is not necessary with the same codec. For communications that require codec conversion, the codec conversion can be kept to a minimum number of times.

  As shown in the above embodiments and examples, in the calling side SBC 300, the SDP is set for each category of a plurality of codecs used in the relay network in accordance with the connection rule for the codec category set by the relay operator. Prioritize and add or delete the codec description in the SDP according to the connection rules. Thereby, the relay company can select the relay codec using the optimum codec without installing new equipment or increasing the equipment.

  In addition, in response to the issue of prompt support for changes in the relationship between telephone numbers and codecs, the relay codec is selected between the calling terminal and the receiving terminal in conjunction with the offer / answer by SIP / SDP. The relay codec is determined based on the codec information actually supported by the receiving terminal and the network. Thereby, even if the number portability and the terminal change occur, it is possible to apply the relay codec so that it matches the codec of the outgoing / incoming terminal and network after the change.

  Furthermore, in order to select a relay codec in accordance with the categorization for the problem of reducing useless codec conversion that occurs in the relay between voice communication providers, in the present invention, in the present invention, the SBC codec rank on both sides of the calling side and the calling side is determined. It proposes collaboration by rearranging and exchanging. Thereby, it becomes possible to reduce the codec conversion function required for the gateway device between the relay network and each communication carrier connected to the relay network.

  In addition, for the issue of ensuring the connectivity of voice communication between all operators connected to the relay network, the connection by the codec belonging to the category of the codec related to the guarantee of durability, as shown in the category classification example, is required. By setting the rule, it is possible to establish a session by a codec belonging to the category by the SDP offer answer. Accordingly, since it is possible to connect to a large number of communication carriers by connecting to the relay network, it is possible to provide a highly reliable voice relay.

  By defining a codec that does not allow category 3 connections for the problem of restricting the use of the network only for services provided by the relay network operator, it is possible to connect services that are not provided by the relay network operator. Can be limited. This facilitates network design and management. In addition, it is possible to prevent the relay network from being dirtied due to the use of services that are not originally provided.

  It is possible to construct the operation of the above SBC 300, 600 as a program and install it on a computer used as the SBC for execution, or distribute it via 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
310 signal routing information reference unit 320 signal processing unit 321 drum control information storage unit 330 relay codec selection unit 331 codec table 340 signal transmission / reception unit 350 media control unit 360 media transmission / reception unit 400 ENUM server 500 relay operator SIP proxy server 600 destination SBC
610 Signal routing information reference unit 620 Signal processing unit 621 Drum control information storage unit 630 Relay codec selection unit 631 Codec table 640 Signal transmission / reception unit 650 Media control unit 660 Media transmission / reception unit

Claims (6)

An originating network connected to the originating terminal, a terminating network connected to the terminating terminal, a relay network connected to the originating network and the terminating network, and a connection to the relay network in the relay network A relay system having a calling codec selection device and a receiving codec selection device for setting a codec that can be used in the relay network for an offer signal and an answer signal transmitted / received in the outgoing network and the incoming network. And
The originating codec selection device is:
Means for holding an offer signal received from the originating network;
A caller codec correspondence table storage means storing a combination of codecs used by a caller of the caller network;
Referring to the caller codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set, and the priority of the codec is changed according to the connection guarantee level of the codec category. Side codec setting means,
The destination codec selection device is
Means for holding an offer signal received from the relay network;
A receiver codec correspondence table storing means for storing a combination of codecs used by the receiver of the destination network;
Referring to the callee codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set as required, and the priority of the codec is set according to the connection guarantee level of the category of the codec. The destination codec setting means to change the order,
A relay system comprising: An originating network connected to the originating terminal, a terminating network connected to the terminating terminal, a relay network connected to the originating network and the terminating network, and a connection to the relay network in the relay network A relay system having a calling codec selection device and a receiving codec selection device for setting a codec that can be used in the relay network for an offer signal and an answer signal transmitted / received in the outgoing network and the incoming network. And
The relay network is
Routing information storage means storing a domain corresponding to the number of the calling terminal and the called terminal, and an ENUM server that responds to an inquiry from the calling codec selection device,
The originating codec selection device is:
Means for querying the ENUM server for the domain of the receiving terminal;
Means for holding an offer signal received from the originating network;
Caller codec correspondence table storage means that sets the codec used by the caller of the caller network for each level of connection guarantee;
Referring to the caller codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set, and the priority of the codec is changed according to the connection guarantee level of the codec category. Side codec setting means,
Means for transmitting the offer signal to the domain of the receiving terminal obtained from the ENUM server;
Have
The destination codec selection device is
Means for holding an offer signal received from the relay network;
A receiver codec correspondence table storage means for setting the codec used by the receiver of the called network for each connection guarantee level;
Referring to the callee codec correspondence table storage means, the codec described in the offer signal and the answer signal is selected and set as required, and the priority of the codec is set according to the connection guarantee level of the category of the codec. A destination codec setting means for changing the order;
A relay system comprising: The sender codec correspondence table storage means and the receiver codec correspondence table storage means are:
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 setting means of the calling codec selection device is:
The offer signal including the codec of the first category is transmitted to the relay network, and the codec of the offer signal received from the originating network is referred to the third category with reference to the caller codec correspondence table storage unit. Means for raising the priority of the codec of the received offer signal,
Means for converting the codec if there is a difference between the answer signal received from the relay network and the offer signal received from the originating network that is held;
Including
The destination side codec rank determining means of the destination side codec selector is:
Means for adding the codec of the destination network to the end of the offer signal and transmitting it to the destination network if the codec of the offer network received from the relay network does not include the codec of the destination network; ,
Based on the codec of the answer signal received from the destination network and the codec of the offer signal received from the relay network that is held, the codec to be set from the callee codec correspondence table storage means is selected and an answer signal is generated Means for transmitting to the relay network;
The relay system according to claim 1, comprising: An originating network connected to the originating terminal, a terminating network connected to the terminating terminal, a relay network connected to the originating network and the terminating network, and a connection to the relay network in the relay network Relay in a relay system having a calling codec selection device and a receiving codec selection device for setting a codec that can be used in the relay network for an offer signal and an answer signal transmitted and received in the originating network and the terminating network. A codec selection method for a net,
The originating codec selection device is:
A first offer information storage means holds an offer signal received from the originating network;
The calling codec setting means refers to the calling codec correspondence table storage means in which combinations of a plurality of codecs used by the calling network provider of the calling network are stored for each connection guarantee level, and offers as needed. Selecting and setting the codec to be described in the signal and the answer signal, and changing the priority of the codec according to the connection guarantee level of the category of the codec,
The destination codec selection device is
A second offer information storage means holds the offer signal received from the relay network;
The called side codec setting means refers to the called codec correspondence table storage means in which combinations of a plurality of codecs used by the called party of the called side network are stored for each connection guarantee level, and the offer signal and the answer signal A codec selection method for a relay network, wherein the codec priority is changed according to the connection guarantee level of the category of the codec. An originating network connected to the originating terminal, a terminating network connected to the terminating terminal, a relay network connected to the originating network and the terminating network, and a connection to the relay network in the relay network A calling codec selection device, a calling codec selection device, and an ENUM server for setting a codec that can be used in the relay network in an offer signal and an answer signal transmitted and received in the originating network and the terminating network. A codec selection method in a relay system having:
The ENUM server is
Routing information storage means storing domains corresponding to the numbers of the calling terminal and the called terminal;
The originating codec selection device is:
Queries the domain of the receiving terminal from the ENUM server,
The ENUM server is
Responding to the domain of the receiving terminal corresponding to the inquiry from the calling codec device,
The originating codec selection device is:
A first offer information storage means holds an offer signal received from the originating network;
The caller codec setting means refers to the caller codec correspondence table storage means in which combinations of a plurality of codecs used by the caller of the caller network are stored for each connection guarantee level, and the offer signal and the answer signal The codec described in the above is selected and set, and the priority of the codec is changed according to the connection guarantee level of the category of the codec.
Send an offer signal to the domain of the called terminal obtained 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;
The called side codec setting means refers to the called codec correspondence table storage means in which combinations of a plurality of codecs used by the called party of the called side network are stored for each connection guarantee level, and the offer signal and the answer signal Selecting and setting the codec described in the above, and changing the priority of the codec according to the connection guarantee level of the category of the codec.
A codec selection method for a relay network. The sender codec correspondence table storage means and the receiver codec correspondence table storage means are:
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;
Storing the first category, a codec that does not belong to the second category, and the lowest third category;
The originating codec selection device is:
The offer signal including the codec of the first category is transmitted to the relay network, and the codec of the offer signal received from the originating network is referred to the third category with reference to the caller codec correspondence table storage unit. If it is not included, the codec priority of the received offer signal is increased and transmitted,
If there is a difference between the answer signal received from the relay network and the held offer signal received from the originating network, the codec is converted and transmitted to the originating network,
The destination codec selection device is
When the codec of the offer side received from the relay network does not include the codec of the destination side network, the codec of the destination side network is added to the end of the offer signal and transmitted to the destination side network,
Based on the codec of the answer signal received from the destination network and the codec of the offer signal received from the relay network that is held, the codec to be set from the callee codec correspondence table storage means is selected and an answer signal is generated 6. The relay network codec selection method according to claim 4 or 5, wherein the relay network codec is selected for transmission to the relay network.

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