JP5233714B2 - Communication media conversion system, method and program - Google Patents

Description

  The present invention relates to a communication media conversion system, method, and program, and can be applied to, for example, a communication media conversion system, method, and program that mutually convert different communication media.

  In recent years, for example, communication on an IP (Internet Protocol) network has been diversified, and various communication terminals as communication tools have appeared, and these communication terminals are used to cooperate in various forms for communication. It has come to be realized.

  For example, various forms of communication are performed such as when a call is made between an IP telephone terminal and a soft phone on a PC.

  When interconnection is performed on the basis of SIP (Session Initiation Protocol) over IP, communication cannot be established unless communication media negotiation is established between the transmitting terminal and the receiving terminal.

  The communication media includes, for example, communication media such as voice and text. For example, when the calling terminal desires voice communication while the receiving terminal desires text communication, the communication media is different. Negotiation is not established and communication between the two is not possible.

  In the negotiation of communication media according to SIP, SDP (Session Description Protocol) information includes media information indicating communication media desired by the transmitting terminal and the receiving terminal, and the SIP server performs media information of the transmitting terminal and the receiving terminal. It is done by judging.

  In Patent Document 1, as an example of means for solving the above-described problem, communication is performed even when communication media are different between a sending terminal and a receiving terminal by a cooperation process with a presence server and a media conversion process between voice and text. The technology to be realized is described.

JP 2008-85838 A

  However, even if the technique described in Patent Document 1 is applied, the caller and the callee are not sure what kind of terminal the other party is communicating with. In some cases, it may take.

  For example, when the communication media of the calling terminal is voice and the communication media of the receiving terminal is text, the callee inputs text, converts the text data into voice data, and then sends it to the caller. Therefore, it can be considered that it takes time to respond from the callee to the caller. In such a case, the caller and the callee may not be able to communicate well because they do not recognize the other party's terminal.

  Further, in the case of the technique described in Patent Document 1, since the procedure is always performed after confirming the presence state, there is a possibility that useless signal reception may be performed even in cases where media conversion is unnecessary.

  For example, in the cooperation process described in Patent Document 1, for example, when determining the media information of the arrival / departure terminal, the SIP server always inquires the presence server about the media information on the called side. However, considering the case where the communication media are the same, media conversion is not necessary, and therefore, it can be realized without processing between the SIP server and the presence server. That is, more efficient linkage processing is desired from the viewpoint of server processing load and processing time, and overall network load.

  Therefore, in view of the above problems, the present invention provides a communication media conversion system, method, and program capable of solving the above problems in consideration of services actually provided and taking into account the policies of the network and the user. To do.

  In the media conversion system of the first aspect of the present invention, (1) a connection request with the second terminal is received from the first terminal, a connection request is made to the second terminal, a response is received from the second terminal, and the first Communication media determining means for determining matching of communication media types between the first terminal and the second terminal based on communication media information permitted to be used by the terminal and the second terminal; and (2) communication between the first terminal and the second terminal. This policy information management means for managing policy information indicating a user policy when the media types do not match, (3) the policy based on the determination result of the communication media determination means, and the policy information of the terminal of the policy information management means Policy execution means for executing processing in accordance with the user policy of information; and (4) if the user policy is to execute media conversion, the policy execution means to the media Receiving a conversion request, characterized in that it comprises a media conversion means performs conversion processing of the media data between the first terminal and the second terminal.

  In the media conversion method of the second aspect of the present invention, (1) the communication media determination means receives a connection request from the first terminal to the second terminal, makes a connection request to the second terminal, and responds from the second terminal. And a communication media determination step for determining a match between the communication media types of the first terminal and the second terminal based on communication media information permitted to be used by the first terminal and the second terminal, and (2) policy information management. A policy information management step for managing policy information indicating a user policy when the communication media types of the first terminal and the second terminal do not match; and (3) a policy execution means is a determination result of the communication media determination means. A policy execution step of executing processing according to the user policy of the policy information based on the policy information of the terminal of the policy information management means, and (4) a media conversion means, A media conversion step of receiving a media conversion request from the policy execution means and performing a conversion process of media data between the first terminal and the second terminal when the user policy is to execute media conversion; .

  A media conversion program according to a third aspect of the present invention provides a computer that (1) receives a connection request from the first terminal to the second terminal, makes a connection request to the second terminal, and receives a response from the second terminal. , Communication media determination means for determining matching of communication media types of the first terminal and the second terminal based on communication media information permitted to be used by the first terminal and the second terminal, and (2) the first terminal and the second terminal. Policy information management means for managing policy information indicating a user policy when the types of communication media do not match, (3) based on the determination result of the communication media determination means and the policy information of the terminal of the policy information management means Policy execution means for executing processing according to the user policy of the policy information; (4) if the user policy is to execute media conversion, the policy execution means In response to Luo media conversion request, characterized in that to function as a media converting means for performing conversion processing of the media data between the first terminal and the second terminal.

  According to the present invention, since it is executed according to the policy information, if communication can be performed without media conversion, communication can be realized quickly, and even if media conversion is required, media conversion can be performed without cooperation with the presence server. Can do. Furthermore, according to the present invention, the communication media type of the communication partner can be notified to each terminal by an appropriate method, so that communication between users can be improved.

It is a block diagram which shows the internal structure of each component of the network system of 1st Embodiment. 1 is a configuration diagram illustrating an overall configuration of a network system according to a first embodiment. It is a block diagram which shows the structure of the policy information of 1st Embodiment. It is a block diagram which shows the structure of the sub policy information of 1st Embodiment. It is a block diagram which shows the structure of the media information of 1st Embodiment. It is a flowchart of the media conversion process of 1st Embodiment. It is a sequence diagram of the media conversion process of 1st Embodiment.

(A) Embodiments Embodiments of a communication media conversion system, method, and program according to the present invention will be described below with reference to the drawings.

  In this embodiment, for example, an embodiment in which the present invention is applied to a network system that establishes a session according to SIP on an IP network and realizes communication between a calling terminal and a receiving terminal will be exemplified.

(A-1) Configuration of Embodiment FIG. 2 is a configuration diagram showing the overall configuration of the network system of this embodiment. FIG. 1 is an internal configuration diagram showing the internal configuration of each component constituting the network system 10 of this embodiment.

  In FIG. 2, the network system 10 according to this embodiment includes an SIP server 1, a media conversion server 2, a presence server 3, a media server 4, a terminal A, and a terminal B on an IP network 5.

  The SIP server 1, the presence server 3 and the terminals A and B perform interworking on a SIP basis. Further, interworking is performed between the SIP server 1 and each server by signal transmission / reception on the IP. That is, the interwork between the servers does not necessarily need to be SIP.

  The IP network 5 is a communication network using IP (Internet Protocol) as a communication protocol. The IP network 5 may be either a wired line or a wireless line. For example, a mobile communication network or a LAN can be applied.

  Terminal A and terminal B are communication terminals that perform communication via the IP network 5. Various terminals having a communication function can be applied to the terminal A and the terminal B, and examples thereof include an IP telephone terminal (a concept including a fixed type and a portable type), a personal computer, and the like. The terminals A and B perform, for example, an instant message using text data such as voice call and chat, a video conference, and the like.

  The SIP server 1 is a server that establishes a session between the terminal A and the terminal B on the IP network 5. As shown in FIG. 1, the SIP server 1 includes a signal processing unit 11, a service control unit 12, a policy control unit 13, a user information management unit 14, and a policy information management unit 15.

  The signal processing unit 11 performs signal transmission / reception control. The signal processing unit 11 transmits and receives control signals (SIP control signals) between the transmitting terminal and the receiving terminal and media signals exchanged between the terminal A and the terminal B.

  The service control unit 12 controls processing of the media conversion service. When there is a connection request from the calling terminal, the service control unit 12 makes a connection request to the receiving terminal, and based on the media information included in the SDP information acquired from the calling terminal and the receiving terminal, matches or mismatches of the communication media. The policy control unit 13 is inquired for a policy corresponding to the determination result of matching or mismatching of the communication media.

  When the service control unit 12 receives a response (action content) according to the policy of the user (transmitting terminal, receiving terminal) from the policy control unit 13, the service control unit 12 executes a process according to this response.

  The policy control unit 13 receives from the service control unit 12 a match / mismatch determination result of the communication media of the transmitting terminal and the receiving terminal, and uses this determination result and the policy information of each user of the policy information management unit 15 to A response according to the information is given to the service control unit 12.

  The user information management unit 14 manages user contract data and media information related to media conversion. FIG. 5 exemplifies media information items for media conversion in the user information management unit 14. As shown in FIG. 5, this media information includes “session identification information”, “transmission source identification information”, “media type”, and “codec”.

  The “session identification information” stores an identifier for identifying a session between the terminals A and B. As shown in FIG. 5, a common identifier is used between the transmitting terminal and the receiving terminal that establish a session. Thereby, it is possible to associate the calling terminal and the receiving terminal related to session establishment.

  For example, the IP address and port number of the transmission source terminal are stored in the “transmission source identification information”. The “media type” stores a communication media type such as voice and text. The “codec” stores the encoding format of the communication media type.

  The policy information management unit 15 manages policy information of each user regarding the media conversion service. This policy information is policy information on the calling user side.

  Here, FIGS. 3 and 4 illustrate the configuration of the policy information of each user. FIG. 3 shows the configuration of main policy information, and FIG. 4 shows the configuration of sub-policy information followed by the policy information.

  The policy information shown in FIG. 3 is a primary user policy in accordance with a determination result of matching or mismatching of communication media between the transmitting terminal and the receiving terminal.

  As shown in FIG. 3, this policy information includes “user” and “action” as items. The “user” stores identification information (for example, user name, identification number, terminal identification information, etc.) of the user who provides the media conversion service. “Action” is a primary response, and stores information such as requiring confirmation of the presence information of the user when receiving an incoming call, media conversion or disconnection when the communication media do not match. Yes.

  For example, the “action” of the user A in FIG. 3 is “perform processing according to the sub-policy with reference to the presence information” regardless of the match / mismatch of the communication media. As a result, when the user A receives an incoming call, the presence information is always confirmed.

  Further, for example, in the case of the “action” of the user B in FIG. 3, the SIP server 1 is set as the presence server because “in accordance with the response condition of the terminal used and the communication is performed by converting the voice to text when the media condition does not match” 3 can take action without confirming presence information. As described above, by providing the policy information as shown in FIG. 3, the SIP server 1 can take action without accessing the presence server 3.

  In FIG. 3, one action is defined for each user. However, a plurality of actions may be defined for each user so that the user can appropriately select a possible action.

  The sub-policy information shown in FIG. 4 is a policy corresponding to the presence state of the user when the presence information needs to be referred to in the policy information shown in FIG.

  As shown in FIG. 4, the sub-policy information has “user”, “presence state”, “providable media”, and “action” as items. “User” is identification information of the user.

  The “presence state” stores the presence state of the user as a condition for determining an action. For example, the user A may be “departure”, “in the office (seat)”, “in the office (during a meeting)”, or the like. The presence state defined in the “presence state” may be arbitrarily determined by each user, or may be determined in advance by the service provider.

  “Providable media” stores communication media to be provided to the user in the presence state stored in the “presence state”. This “providable medium” is determined, for example, when the user contracts. Moreover, you may enable it to change suitably.

  “Action” stores correspondence that can be taken in the case of the presence state stored in the “presence state”.

  The media conversion server 2 is a server that converts communication media, and performs, for example, conversion processing between audio data and text data. As shown in FIG. 1, the media conversion server 2 includes a signal processing unit 21, a speech recognition processing unit 22, a speech / text conversion processing unit 23, and an RTP control unit 24.

  The signal processing unit 21 performs signal transmission / reception control. The signal processing unit 21 performs mutual connection with the SIP server 1 according to IP.

  The RTP control unit 24 performs communication control according to RTP (Real-time Transport Protocol). Media packets are RTP standardized packets, and media information is exchanged via an RTP session. Further, the RTP control unit 24 analyzes the received packet, performs media type such as text data and voice data, and forms transmission data into an RTP packet.

  The voice recognition processing unit 22 recognizes voice based on voice data received via the RTP session when voice data is converted into text data. The voice recognized here is converted into text data by the voice / text conversion processing unit 23.

  The voice / text conversion processing unit 23 converts voice data recognized by the voice recognition processing unit 22 into text data or converts text data into voice data. There are various encoding formats for the audio data, and the audio / text conversion processing unit 23 converts the audio data into audio data in an encoding format that can be supported by the counterpart terminal. In addition, when converting text data into speech data, the speech / text conversion processing unit 23 synthesizes speech from the text data and converts it into speech data.

  The presence server 3 manages the presence status (location information) of the user (terminal) that provides the service. As shown in FIG. 1, the presence server 3 includes a signal processing unit 31, a presence information processing unit 32, and a presence information management unit 33.

  The signal processing unit 31 performs signal transmission / reception control. The signal processing unit 31 performs mutual connection with the SIP server 1 according to SIP.

  The presence information processing unit 32 performs processing related to the presence information of the user (terminal), and performs, for example, user terminal registration processing, user (terminal) presence status acquisition processing, presence information update processing, and the like. .

  The presence information management unit 33 manages presence information indicating the presence status of the terminal. This presence information is information in which terminal identification information (for example, a user ID, a terminal ID, or an IP address) is associated with a presence state (position information). Further, as the presence information, information indicating communication media that can be used by the terminal may be placed.

  When performing inter-terminal communication with media conversion, the media server 4 notifies the terminal that uses voice as the communication medium of the content that the partner terminal performs communication by text input. As shown in FIG. 1, the media server 4 includes a signal processing unit 41 and an RTP control unit 42.

  The signal processing unit 41 performs signal transmission / reception control.

  The RTP control unit 42 performs communication control according to RTP. When performing the above notification to a terminal that uses voice as a communication medium, the RTP control unit 42 connects the terminal with the RTP session and transmits an RTP packet having the voice data of the notification to the terminal.

(A-2) Operation of Embodiment Next, interworking in the media conversion system of this embodiment will be described with reference to the drawings.

  FIG. 6 is a flowchart showing processing in the media conversion system of this embodiment. FIG. 7 shows a case where terminal A is a calling terminal and terminal B is a receiving terminal. Terminal A uses voice as communication media, and terminal B uses text as communication media. The sequence diagram at the time is shown.

  In FIG. 6, when starting communication (step S <b> 101), the calling terminal transmits a connection request to the SIP server 1. When the SIP server 1 detects a connection request from the calling terminal (step S102), it makes a connection request (offer) to the receiving terminal (step S103), and receives response information from the receiving terminal (step S104).

  At this time, for example, since the calling terminal describes the desired communication media in INVITE with SDP, the SIP server 1 stores the IP address, port number, media type, and codec of the calling terminal as media information. In addition, since the SIP server 1 makes an offer to the receiving terminal using INVITE with SDP, the IP address and port number of the receiving terminal, the media type, and the response information received from the receiving terminal (200 OK with SDP) The codec is stored as media information. As a result, it is possible to know the IP address and port number, the media type, and the codec of both the outgoing and incoming terminals for the common session identification information.

  Next, in the SIP server 1, the service control unit 12 determines whether the communication media desired by the calling terminal and the receiving terminal match (step S105). At this time, if the communication media of the calling terminal and the receiving terminal match, the process moves to step S106, and if they do not match, the process moves to step S111.

  When the communication media of the calling terminal and the receiving terminal match, in the SIP server 1, the policy control unit 13 reads the policy information (see FIG. 3) of the user of the calling terminal, and the service control unit 12 Response processing according to the policy is performed (step S106).

  At this time, if the action of the user's policy information is not the content referring to the presence information, the service control unit 12 performs a normal connection process without cooperating with the presence server 3 (step S107).

  On the other hand, when the action of the policy information of the user is content that refers to the presence information, the service control unit 12 requests the presence server 3 for the presence information of the user and acquires the presence information of the user.

  Then, the policy control unit 13 reads the user's sub-policy information (see FIG. 4), determines whether there is an action corresponding to the user's presence information (that is, determines whether the connection condition is met) (step S108). If the connection conditions are met, the service control unit 12 performs a connection process (step S109), and if not, the service control unit 12 performs a disconnection process (step S110).

  If the communication media of the calling terminal and the receiving terminal do not match in step S105, in the SIP server 1, the policy control unit 13 reads the policy information (see FIG. 3) of the user of the calling terminal, and the service control unit 12 The corresponding processing according to the user policy is performed (step S111).

  For example, the policy information illustrated in FIG. 3 illustrates three actions: an action according to sub-policy information with reference to presence information, an action of converting media without checking the presence state, and an action of disconnecting. 6 also illustrates these cases.

  If the action is to be disconnected by referring to the policy information in step S111, the service control unit 12 performs a disconnection process (step S112).

  In the case of an action according to sub-policy information by referring to presence information by referring to policy information, the service control unit 12 requests presence information of the user from the presence server 3 and obtains the presence information of the user. To do.

  Then, the policy control unit 13 reads the user's sub-policy information (see FIG. 4), determines whether there is an action corresponding to the user's presence information (that is, determines whether the connection condition is met) (step S113). If they do not match, the service control unit 12 performs a disconnection process (step S114).

  If the connection conditions match, the service control unit 12 connects to the media conversion server 2 (step S115).

  When it is desired to refer to the policy information in step S111, the service control unit 12 is also connected to the media conversion server 2 when the policy information performs media conversion (step S115).

  The media conversion server 2 performs media conversion processing instructed by the SIP server 1. At this time, the media conversion server 2 notifies the calling terminal and the receiving terminal that the communication partner terminal is connected by media conversion before performing communication between the calling terminal and the receiving terminal (step S116).

  In this notification method, the media server 4 transmits a voice to that effect through a RTP session to a user (terminal) that communicates by voice, and the SIP server 1 is sent to a user (terminal) that communicates by text. Via the SIP message (SIP MESSAGE method).

  After notifying the contents of the media conversion connection in step S116, communication between both terminals is performed via the media conversion server 2 (step S117).

  Next, the operation of the media conversion process will be described with reference to the sequence diagram shown in FIG.

  First, the calling terminal A makes a connection request to the SIP server 1 using INVITE with SDP. Further, the SIP server 1 issues a connection request to the destination terminal B by INVITE with SDP (step S201).

  As described above, since the communication media of the terminals A and B are described in the SDP, the SIP server 1 determines whether or not both terminals A and B match by comparing the communication media ( Step S202).

  In this example, the communication medium of terminal A is voice, whereas the communication medium of terminal B is text, so they do not match each other. Therefore, the process proceeds to step S111 in FIG.

  In the SIP server 1, referring to the action of the policy information of the terminal (user) A on the calling side shown in FIG. 3, the processing is performed according to the sub-policy with reference to the presence information. In step S113, the SIP server 1 collects user presence information from the presence server 3 (step S203).

  For example, it is assumed that the presence status of the user (terminal) A is “destination” and the media that can be provided is only “voice”, whereas the communication media of the user (terminal) B is only “text”. Then, since the two communication media conditions do not match, the process proceeds to S115 in FIG. 6, and the SIP server 1 makes a media conversion communication request to the media conversion server 2 (step S204).

  The media conversion server 2 transmits the INVITE with SDP to the media server 4 and connects to the media server 4 because the communication media of the terminal A is voice, and establishes an RTP session between the media server 4 and the terminal A. Then, the media server 4 notifies the terminal A by voice that the partner terminal communicates text input (step S205). This voice notification can be realized by preparing a voice message in advance by the media server.

  Further, since the communication medium of the terminal B is text, the media conversion server 2 sends an SIP message (MESSAGE method) including the content that the partner terminal is a voice communication terminal to the terminal B via the SIP server 1. Transmit (step S206).

  Thereafter, the media conversion server 2 instructs the terminal A to start communication with the SIP message, and performs communication between the communication A and the terminal B while converting the communication media (step S207).

  For example, the media conversion server 2 recognizes the voice data received from the terminal A via the RTP session, converts the voice data to text data, and transmits the converted text data to the terminal B as a SIP message via the SIP server 1. To do. Conversely, when the text data from the terminal B is received via the SIP server 1, the media conversion server 2 converts (synthesizes) the text data into voice data, and transmits the voice data to the terminal A via the RTP session.

(A-3) Effect of Embodiment As described above, according to this embodiment, when communication is possible without media conversion, communication between users is possible by controlling only the SIP server. Further, according to this embodiment, even when media conversion is necessary, interworking according to the user policy information eliminates the need for all users to cooperate with the presence server.

  Furthermore, according to this embodiment, when communicating by media conversion, the caller and the callee are notified of how the other party communicates, so that communication in consideration of the other party is possible. Become. For example, since it is known in advance that the other party is inputting text, there may be no particular problem even if the response is slow. That is, communication between users can be improved.

(B) Other Embodiments Each server (SIP server, media conversion server, media server, presence server) constituting the network system 10 of the above-described embodiment has been described as a physically different device. As long as the functions described in the embodiments can be realized, the devices may be physically the same.

  The policy information and sub-policy information described in FIGS. 3 and 4 may include items other than the items illustrated in FIGS. 3 and 4.

  The exchange (signal transmission / reception) between the servers (SIP server, media conversion server, media server, presence server) described in the above-described embodiments does not have to be SIP. That is, it is only necessary to be able to perform cooperation processing between the servers, and the communication protocol between the servers for that purpose is not particularly limited.

  Although the interworking of the media conversion system of the present invention depends on the setting of policy information, the presence server is not an essential component in terms of system.

  In the above-described embodiment, when referring to the user policy information, the caller's policy information is referred to. However, the caller's policy information may be referred to. As a result, an action according to the policy of the called party can be performed.

  For example, in the case of IP telephone communication, even if the same IP telephone communication medium is used, for example, G. 711 μ-law and G.I. There are cases where the audio encoding format is different as in 722.1. The present invention can also be applied to cases where the speech encoding formats are different.

DESCRIPTION OF SYMBOLS 1 ... SIP server, 11 ... Signal processing part, 12 ... Service control part, 13 ... Policy control part, 14 ... User information management part, 15 ... Policy information management part,
2 ... Media conversion server, 21 ... Signal processing unit, 22 ... Voice recognition processing unit,
23 ... voice / text conversion processing unit, 24 ... RTP control unit,
3 ... Presence server, 31 ... Signal processing unit, 32 ... Presence information processing unit,
33 ... Presence information management department,
4 ... Media server, 41 ... Signal processing unit, 42 ... RTP control unit,
A and B ... terminal, 10 ... network system.

Claims (6)

A connection request to the second terminal is received from the first terminal, a connection request is made to the second terminal, a response is received from the second terminal, and communication permitted to use the first terminal and the second terminal is received. Communication media determining means for determining matching of communication media types of the first terminal and the second terminal based on media information;
Policy information management means for managing policy information indicating a user policy when the communication media types of the first terminal and the second terminal do not match;
Policy execution means for executing processing according to the user policy of the policy information based on the determination result of the communication media determination means and the policy information of the terminal of the policy information management means;
Media conversion means for receiving a media conversion request from the policy execution means and performing media data conversion processing between the first terminal and the second terminal when the user policy is to execute media conversion; A media conversion system characterized by that. The policy information management means further manages sub-policy information indicating a user policy determined according to presence information of the terminal when the communication media type does not match,
2. The policy execution means collects presence information of the terminal from presence management means for performing presence management of the terminal when the policy information is to be processed according to the sub-policy information. The media conversion system described in 1.   3. The media conversion according to claim 1, wherein the media conversion means notifies the communication media of a communication partner terminal by using the communication media type of the first terminal and the second terminal before the start of communication. system.   4. The media conversion system according to claim 3, wherein the media conversion means notifies a terminal using voice as a communication medium by voice communication, and notifies a terminal using text as a communication medium by a text message. The communication media determination means receives a connection request from the first terminal to the second terminal, makes a connection request to the second terminal, receives a response from the second terminal, and receives the response from the first terminal and the second terminal. A communication media determination step for determining a match between the types of communication media of the first terminal and the second terminal based on communication media information permitted to be used by the terminal;
A policy information management step in which policy information management means manages policy information indicating a user policy when the communication media types of the first terminal and the second terminal do not match;
A policy execution step in which the policy execution means executes processing according to the user policy of the policy information based on the determination result of the communication media determination means and the policy information of the terminal of the policy information management means;
In the case where the media conversion means causes the user policy to execute media conversion, the media that receives the media conversion request from the policy execution means and performs media data conversion processing between the first terminal and the second terminal A media conversion method comprising: a conversion step. Computer
A connection request to the second terminal is received from the first terminal, a connection request is made to the second terminal, a response is received from the second terminal, and communication permitted to use the first terminal and the second terminal is received. Communication media determining means for determining matching of communication media types of the first terminal and the second terminal based on media information;
Policy information management means for managing policy information indicating a user policy when the communication media types of the first terminal and the second terminal do not match;
Policy execution means for executing processing according to the user policy of the policy information based on the determination result of the communication media determination means and the policy information of the terminal of the policy information management means,
When the user policy is to execute media conversion, it receives a media conversion request from the policy execution means and functions as media conversion means for performing media data conversion processing between the first terminal and the second terminal. A media conversion program characterized by that.

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