WO2010134420A1

WO2010134420A1 - Communication system and communication method

Info

Publication number: WO2010134420A1
Application number: PCT/JP2010/057350
Authority: WO
Inventors: 賢輔松島
Original assignee: 日本電気株式会社
Priority date: 2009-05-18
Filing date: 2010-04-26
Publication date: 2010-11-25

Abstract

A communication system comprises an audio encoding information notifying means and a resource providing means (33). The audio encoding information notifying means is included in a first network (50) which is able to recognize the audio encoding scheme a terminal uses in communication and which is connected to a second network (30). The audio encoding information notifying means transmits, to the second network (30), audio encoding information indicating the audio encoding scheme used at a terminal which is attempting to use a service of the second network (30) via the first network (50). The resource providing means (33) is included in the second network (30) and receives audio encoding information relating to the terminal from the audio encoding information notifying means, and transmits, to the terminal, audio data encoded by the audio encoding scheme indicated by the audio encoding information.

Description

Communication system and communication method

The present invention relates to a communication method in a communication system in which a plurality of networks are connected.

The 3G (3rd Generation) network, which is a third-generation mobile phone network, provides voice services using a circuit switching system.

In addition, IMS (IP Multimedia Subsystem), which provides various multimedia services by implementing voice services that have been provided by the circuit switching method on the IP (Internet Protocol) network, is now 3GPP (3rd Generation Partnership Project) and 3GPP2 (3rd Generation Partnership Project 2) (see Non-Patent Documents 1 and 3). By connecting the third generation mobile phone to the IMS, the user can receive various multimedia services.

FIG. 1 shows an example of a communication system that connects a 3G network and an IMS.

As shown in FIG. 1, a communication system that connects a 3G network and an IMS includes a calling side 3G network 10, a called side 3G network 20, an IMS 30, and a PSTN (Public Switched Telephone Networks) / IP network 40.

The PSTN / IP network 40 is a PSTN that is a general subscriber telephone line network or an IP network such as the Internet.

The originating 3G network 10, the terminating 3G network 20, and the IMS 30 are connected by a PSTN / IP network 40.

The originating 3G network 10 includes a Node-B / RNC 12, an MSCS 13, a GMSCS 14, and CS-MGWs 15 and 16.

Similarly, the destination side 3G network 20 includes a Node-B / RNC 22, an MSCS 23, a GMSCS 24, and CS-MGWs 25 and 26.

3G-CS (3rd Generation-Circuit Switching)

terminals

11 and 21 are terminals such as third-generation mobile phones that support the circuit switching system.

The 3G-CS terminal 11 is connected to the originating 3G network 10. The 3G-CS terminal 21 is connected to the destination 3G network 20.

Node-B / RNC (Radio Network Controller) 12 and 22 have a function of a radio base station that connects to the 3G-

CS terminals

11 and 21 via a radio line and a function of a radio network controller that controls the radio base station.

MSCS (Mobile Switching Center Server) 13 and 23 are mobile communication exchange servers that control call processing.

GMSCS (Gateway Mobile Switching Center Server) 14 and 24 are gateway mobile communication exchange servers having an interconnection function with the PSTN / IP network 40.

CS-MGW (Circuit Switching-Media Gateway) 15, 16, 25, and 26 are media gateways connecting the telephone exchange network and the IP network, and are U-transmitted and received between the 3G network and the PSTN / IP network 40. Plane (User-Plane) data interface conversion is performed.

The IMS 30 has a CSCF 31, an IM-MGW 32, and an MRF 33.

The CSCF (Call Session Control Function) 31 is a device such as a SIP (Session Initiation Protocol) server that provides a call session control function.

An IM-MGW (IMS-Media Gateway) 32 is a media gateway used in the IMS, and performs an interface conversion of U-Plane data transmitted and received between the IMS 30 and the PSTN / IP network 40.

An MRF (Multimedia Resource Function) 33 is a device that provides a multimedia resource function that handles image data, audio data, and the like. The MRF 33 includes an MRFC (MRF Controller) 34 that is a control unit and an MRFP (MRF Processing) 35 that is a processing unit.

Note that the Node-B /

RNCs

12 and 22 are connected to the MSCS 13 and 23 and the CS-

MGWs

15 and 25 via an IuCS interface defined by 3GPP.

MSCS13, 23, CS-MGW15, 25 and GMSCS14, 24, CS-MGW16, 26 are connected by an Nb interface defined by 3GPP.

In addition, the PSTN / IP network 40, the IM-MGW 32, and the MRF 33 are connected through an Mb interface defined by 3GPP.

The originating 3G-CS terminal 11 connects the call through the MSCS 13 and the GMSCS 14 via the Node-B / RNC 12. The 3G-CS terminal 11 is connected to the destination 3G-CS terminal 21 via the Node-B / RNC 12, CS-MGWs 15 and 16, the destination CS-MGWs 26 and 25, and the destination Node-B / RNC 22. And U-Plane data are transmitted and received.

Further, the 3G-CS terminal 11 is connected to the IMS 30 via the PSTN / IP network 40, can communicate with a SIP terminal (not shown) existing in the IMS 30, and can receive various multimedia services.

The MRF 33 existing in the IMS 30 has voice data such as voice guidance and RBT (Ring Back Tone), and can provide voice services to users. However, since the 3G network and the IMS have different network architectures, the voice data included in the MRF 33 is used only by SIP terminals (not shown) existing in the IMS 30. In order for the 3G-

CS terminals

11 and 21 to receive the same voice service, a sound source device (not shown) existing in the 3G network must be used.

Patent Document 1 proposes a technique for switching between MRFs that provide voice services depending on whether a receiving terminal exists in a 3G network or an IMS when a terminal that exists in IMS makes a call. Originally, in IMS, incoming service control is performed in the visited network of the receiving terminal, and in 3G network, incoming service control is performed in the visited network of the transmitting terminal. For this reason, when a terminal existing in the IMS makes a call to a terminal existing in the 3G network, it cannot receive incoming service control of the 3G network. In order to solve this problem, in Patent Document 1, when a terminal that exists in IMS makes a call to a terminal that exists in a 3G network, the incoming call service is received using the MRF that exists in the IMS to which the calling terminal belongs and exists in IMS. When the call is transmitted to the terminal, control is performed so as to receive the incoming service using the MRF existing in the IMS to which the called terminal belongs.

Also, Patent Document 2 proposes a technique for connecting a 3G network and an IMS without using an existing PSTN / IP network. In Patent Document 2, instead of CS-MGW, an interworking device that can be interconnected with IMS IM-MGW is installed to allow 3G-CS terminals to be accommodated directly in IMS.

JP 2009-55455 A JP 2008-205698 A

As described above, since the 3G network and the IMS have different network architectures, terminals existing in the 3G network cannot use voice data included in the MRF existing in the IMS.

The technique of Patent Document 1 is a technique for determining which MRF existing in the IMS is used by the terminal existing in the IMS. The terminal existing in the 3G network has the MRF existing in the IMS. It cannot be applied to the usage of using audio data.

An object of the present invention is to provide a technology for a terminal of a 3G network to use voice data included in an MRF existing in IMS in a communication system having a 3G network and IMS connected by an interworking device. is there.

In order to achieve the above object, the communication system of the present invention is capable of recognizing a speech coding method used by a terminal for communication, and is included in a first network connected to a second network. Voice encoded information notifying means for transmitting to the second network voice encoded information indicating a voice encoding method used by a terminal that intends to use the service of the second network via the network of
Receiving from the speech encoding information notifying means speech encoding information relating to a terminal included in the second network and attempting to use the service of the second network via the first network; And resource providing means for transmitting the voice data encoded by the voice encoding method indicated by the voice encoding information.

In order to achieve the above object, a communication method of the present invention is a communication method of a communication system in which a first network and a second network are connected,
Speech encoded information notifying means included in the first network,
Recognizing a speech encoding method used by a terminal that intends to use the service of the second network via the first network;
Transmitting voice coding information indicating the voice coding method used in the terminal to the second network;
Resource providing means included in the second network includes:
Receiving from the speech coding information notification means speech coding information relating to a terminal that intends to use the service of the second network via the first network;
Audio data encoded by the audio encoding method indicated by the audio encoding information is transmitted to the terminal.

According to the present invention, in a communication system having a 3G network and an IMS connected by an interworking device, a terminal of the 3G network can use voice data possessed by the MRF existing in the IMS.

It is a block diagram which shows the structure of the communication system which connects 3G network and IMS. It is a block diagram which shows the structure of the communication system in one Embodiment of this invention. It is a figure which shows the example of AMR information. It is a figure for demonstrating the example which switches the apparatus which IWF57 connects. It is a figure for demonstrating the example of the protocol converted according to the apparatus which IWF57 connects. 3 is a diagram illustrating a sequence among 3G-CS terminal 51, Node-B / RNC 52, MSCS 53, IWF 57, CSCF 31, MRFC 34, and MRFP 35 when 3G-CS terminal 51 of 3G network 50 is connected to IMS 30. FIG.

Next, the present invention will be described in detail with reference to the drawings.

In order for a terminal of the 3G network to use the voice data of the MRF existing in the IMS, a voice coding method and a voice coding rate (hereinafter referred to as a voice coding rate) used by the terminal of the 3G network. In other words, it is necessary to perform encoding with a voice encoding method.

It is specified in 3GPP TS 25.415 that an RNC or MSCS existing in a 3G network has information on a voice encoding method used by a terminal of the 3G network (see Non-Patent Document 2). However, each device existing in the IMS does not have information on the voice encoding method used by the terminal of the 3G network.

Therefore, in the communication system according to the present embodiment, when a terminal of the 3G network connects to the IMS, the CSCF existing in the IMS acquires the voice encoding scheme used by the terminal connected to the IMS and notifies the MRF. The MRF encodes audio data according to the notified audio encoding method and provides the encoded audio data to a terminal of the 3G network.

FIG. 2 is a block diagram showing a configuration of a communication system according to an embodiment of the present invention.

As shown in FIG. 2, the communication system according to the embodiment of the present invention has a plurality of networks. In a communication system according to an embodiment of the present invention, a 3G network 50 that is a first network and an IMS 30 that is a second network are connected, and a PSTN network 70 that is a third network is further connected to the IMS 30. The

The 3G network 50 includes a calling-side Node-B / RNC 52, a called-side Node-B / RNC 62, an MSCS 53, and an IWF 57. The originating 3G-CS terminal 51 and the terminating 3G-CS terminal 61 are connected to the 3G network 50.

The 3G-

CS terminals

51 and 61 are terminals such as third-generation mobile phones that support the circuit switching method. The 3G-

CS terminals

51 and 61 use AMR (adaptive multi-rate) as a speech encoding method.

The Node-B /

RNCs

52 and 62 have a function of a radio base station that connects to the 3G-

CS terminals

51 and 61 via a radio channel and a function of a radio network controller that controls the radio base station.

The MSCS 53 is a mobile communication exchange server that controls call processing.

The MSCS 53 performs call processing with the CSCF 31 in response to a call connection request from the 3G-

CS terminals

51 and 61.

Further, the MSCS 53 operates as a voice encoded information notification unit. When the AMR speech encoding method used by the 3G-CS terminal 51 is determined in call processing, the MSCS 53 recognizes the determined speech encoding method and is AMR which is speech encoding information indicating information on the speech encoding method. Information is set in the IWF 57. Further, upon receiving an AMR information acquisition request from the CSCF 31, the MSCS 53 notifies the CSCF 31 of the AMR information.

Fig. 3 shows an example of AMR information. The AMR information shown in FIG. 3 is RFCI (RAB sub-flow combination indicator) information defined by AMR.

An IWF (Interworking Function) 57 is an interworking device having an interworking function for interconnecting the 3G network 50 and the IMS 30. The IWF 57 supports various communication forms by switching devices to be connected.

The IWF 57 acquires the AMR information of the 3G-CS terminal connected to the IMS 30 from the MSCS 53.

The IMS 30 has a CSCF 31, an IM-MGW 32, and an MRF 33.

The CSCF 31 is a call session control device such as a SIP server that controls a call session.

The CSCF 31 acquires the AMR information of the 3G-CS terminal connected to the IMS 30 from the MSCS 53 and notifies the acquired AMR information to the MRFC 34.

The IM-MGW 32 is a media gateway used in the IMS 30, and performs conversion of an interface of U-Plane data transmitted and received between the IMS 30 and the PSTN network 70.

The MRF 33 is a resource providing device that provides multimedia resources such as image data and audio data. The MRF 33 includes an MRFC 34 that is a control unit and an MRFP 35 that is a processing unit.

MRFC 34 acquires the AMR information of 3G-

CS terminals

51 and 61 connected to IMS from CSCF 31.

MRFP 35 has voice data such as voice guidance and RBT in advance. The MRFP 35 encodes the audio data based on the AMR information acquired by the MRFC 34 and transmits it to the IWF 57.

The PSTN network 70 is a PSTN which is a general subscriber telephone line network.

Note that the Node-B /

RNCs

52 and 62 are connected to the MSCS 53 and the IWF 57 via an IuCS interface defined by 3GPP.

In addition, the 3G network 50 and the IMS 30 are connected by an Mb interface and an Nb interface defined by 3GPP.

In the communication system shown in FIG. 2, when the originating 3G-CS terminal 51 connects to the IMS 30, the IWF 57 temporarily connects to the MRF 33, and voice guidance from the MRF 33 and RBT voice data are transmitted to the 3G-CS terminal 51. Send to. Thereafter, the IWF 57 disconnects the connection with the MRF 33 and connects with the IM-MGW 32 so that the 3G-CS terminal 51 communicates with a SIP terminal (not shown) existing in the IMS 30.

FIG. 4 is a diagram for explaining an example of switching the device to which the IWF 57 is connected.

For example, the IWF 57 is connected to the Node-B / RNC 52, and further connected to the MRF 33, so that voice data such as voice guidance and RBT from the MRF 33 can be transmitted to the 3G-CS terminal 51.

Further, by connecting the IWF 57 to the Node-B / RNC 52 and further to the IM-MGW 32, the originating 3G-CS terminal 51 can communicate with a SIP terminal (not shown) existing in the IMS 30. .

Further, the IWF 57 is connected to the calling-side Node-B / RNC 52 and further to the called-side Node-B / RNC 62, whereby the calling-side 3G-CS terminal 51 is connected to the called-side 3G-CS terminal. 61 can communicate.

FIG. 5 is a diagram for explaining an example of a protocol to be converted according to a device to which the IWF 57 is connected.

For example, when the IWF 57 is connected to the Node-B / RNC 52 and further connected to the MRF 33, the IWF 57 converts an ATM (Asynchronous Transfer Mode) packet received from the Node-B / RNC 52 into an IP packet and transmits the packet to the MRF 33. . Also, the IWF 57 converts the IP packet received from the MRF 33 into an ATM packet and transmits it to the Node-B / RNC 52.

In addition, when the IWF 57 is connected to the Node-B / RNC 52 and further connected to the IM-MGW 32, the IWF 57 converts the ATM packet received from the Node-B / RNC 52 into an IP packet and transmits it to the IM-MGW 32. The IWF 57 converts the IP packet received from the IM-MGW 32 into an ATM packet and transmits the ATM packet to the Node-B / RNC 52.

Further, when the IWF 57 is connected to the originating Node-B / RNC 52 and further to the terminating Node-B / RNC 62, the IWF 57 transfers the ATM packet without conversion.

Next, the process of notifying the AMR information to the MRF 33 when the 3G-CS terminal 51 of the 3G network 50 is connected to the IMS 30 in the communication system shown in FIG.

FIG. 6 shows the 3G-CS terminal 51, the Node-B / RNC 52, the MSCS 53, the IWF 57, the CSCF 31, the MRFC 34, and the MRFP 35 when the 3G-CS terminal 51 of the 3G network 50 is connected to the IMS 30 in the communication system shown in FIG. It is a figure which shows the sequence between.

When connecting to the IMS 30, the 3G-CS terminal 51 first requests the Node-B / RNC 52 to connect the call (step S1). When a call connection is requested from the 3G-CS terminal 51, the Node-B / RNC 52 requests the MSCS 53 to connect the requested call (step S2). When the MSCS 53 is requested to connect a call, the MSCS 53 performs a call connection process with the CSCF 31 of the IMS 30 (step S3).

When the AMR speech encoding method used by the 3G-CS terminal 51 is determined in the call connection process, the MSCS 53 notifies the IWF 57 of an AMR information setting request indicating a setting request for the AMR information used by the 3G-CS terminal 51 ( Step S4). When receiving the AMR information setting request from the MSCS 53, the IWF 57 sets the designated AMR information in its own apparatus and transmits an AMR information setting response to the MSCS 53 (step S5).

When the AMR speech encoding method used by the 3G-CS terminal 51 is determined in the call connection process, the CSCF 31 notifies the MSCS 53 of an AMR information acquisition request indicating an acquisition request for the AMR information used by the 3G-CS terminal 51. (Step S6). When receiving the AMR information acquisition request from the CSCF 31, the MSCS 53 notifies the CSCF 31 of an AMR information acquisition response including the AMR information used by the 3G-CS terminal 51 (step S7).

When receiving the AMR information acquisition response from the MSCS 53, the CSCF 31 extracts the AMR information from the received AMR information acquisition response, and notifies the AMR information to the MRFC 34 (step S8).

When receiving the AMR information from the CSCF 31, the MRFC 34 notifies the MRFP 35 of an AMR information instruction including the AMR information used by the 3G-CS terminal 51 (step S9). When receiving the AMR information instruction from the MRFC 34, the MRFP 35 extracts the AMR information from the received AMR information instruction, stores it in its own apparatus, and transmits an AMR information instruction response to the MRFC 34 (step S10).

When receiving the AMR information instruction response from the MRFP 35, the MRFC 34 transmits an AMR information notification response to the CSCF 31 (step S11).

Thereby, the MRFP 35 can recognize the AMR information used by the 3G-CS terminal 51 and perform encoding according to the acquired AMR information when transmitting voice guidance or RBT to the 3G-CS terminal 51.

After that, the IWF 57 is connected to the Node-B / RNC 52 and further to the MRF 33, so that the voice guidance encoded by the MRF 33 according to the AMR information used in the 3G-CS terminal 51 and the RBT voice data are converted to the 3G- It is transmitted to the CS terminal 51.

Further, when the IWF 57 disconnects the connection with the MRF 33 and connects with the IM-MGW 32, the 3G-CS terminal 51 can transmit / receive U-Plane data to / from the SIP terminal (not shown) existing in the IMS 30.

When communicating in the 3G network, the originating 3G-CS terminal 51 requests the MSCS 53 to connect a call via the Node-B / RNC 52. The MSCS 53 that is requested to connect the call connects to the called-side Node-B / RNC 62, whereby the calling-side 3G-CS terminal 51 connects to the called-side 3G-CS terminal 61. When connected to the terminating 3G-CS terminal 61, the originating 3G-CS terminal 51 passes through the originating Node-B / RNC 52, IWF 57, and the terminating Node-B / RNC 62 to the terminating 3G-CS terminal. The terminal 61 transmits / receives U-Plane data.

As described above, according to the present embodiment, the MRF can acquire the speech coding scheme used by the 3G-CS terminal connected to the IMS. As a result, the MRF encodes the voice data according to the acquired voice coding method and provides the voice data to the 3G-CS terminal, and the 3G-CS terminal can use the voice data from the MRF.

In addition, the CSCF notifies the MRF of the voice encoding method used by the 3G-CS terminal, so that a communication system can be constructed without adding a new device to the existing system.

In addition, when the IWF interconnects the 3G network and the IMS, the connection of the devices in the communication system can be switched flexibly. At this time, since the data encoded by the common audio encoding method is transmitted and received between the 3G network and the IMS, the IWF disconnects the call of the connected device and changes the audio encoding method of the device. Connections can be switched without changing them.

In the present embodiment, the MSCS operates as the speech coding information notification means and notifies the CSCF of the speech coding scheme used by the 3G-CS terminal. However, the present invention is not limited to this. Is not to be done. The RNC may operate as speech encoding information notification means and notify the CSCF of the speech encoding scheme used by the 3G-CS terminal. When the MSCS operates as voice encoded information notification means, an increase in the processing load of the RNC can be suppressed, and when the RNC operates as voice encoded information notification means, an increase in the processing load of the MSCS can be suppressed.

Further, the AMR information acquisition request, the AMR information acquisition response, the AMR information notification, and the AMR information notification response shown in the present embodiment are transmitted and received based on, for example, the SIP (Session Initiation Protocol) standard. Accordingly, the present invention can be easily applied to a communication system that establishes a communication session using SIP.

In addition, the AMR information instruction and the AMR information instruction response shown in the present embodiment are transmitted and received based on MEGACO (Media Gateway Control Protocol), which is a standard stipulated by the IETF, which has a high affinity with SIP, for example. Is done. Accordingly, the present invention can be easily applied to a communication system that establishes a communication session using SIP.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2009-119824 filed on May 18, 2009, the entire disclosure of which is incorporated herein.

10 Originating 3G network 20 Terminating 3G network 50

3G networks

11, 21, 51, 61 3G-

CS terminals

12, 22, 52, 62 Node-B / RNC
13, 23, 53 MSCS
14, 24 GMSCS
15, 16, 25, 26 CS-MGW
57 IWF
30 IMS
31 CSCF
32 IM-MGW
33 MRF
34 MRFC
35 MRFP
40 PSTN / IP network 70 PSTN network

Claims

The terminal can recognize the voice encoding method used for communication, is included in the first network connected to the second network, and tries to use the service of the second network via the first network. Speech encoding information notifying means for transmitting speech encoding information indicating the speech encoding scheme used in the terminal to the second network;
Receiving from the speech encoding information notifying means speech encoding information relating to a terminal included in the second network and attempting to use the service of the second network via the first network; Resource providing means for transmitting audio data encoded by the audio encoding method indicated by the audio encoding information;
A communication system.
Included in the second network, controls a call session of the terminal to the second network, and obtains speech coding information related to the terminal from the speech coding information notification means in the control of the call session. The communication system according to claim 1, further comprising call session control means for providing said speech coding information to said resource providing means.
The system further comprises an interworking unit included in the first network and connecting the terminal to the resource providing unit of the first network when the terminal uses the service of the second network. The communication system according to 1 or 2.
The communication system according to any one of claims 1 to 3, wherein the voice encoded information notification means is included in a radio network controller existing in the first network.
The communication system according to any one of claims 1 to 3, wherein the voice encoded information notification means is included in a mobile communication switching server existing in the first network.
The communication system according to any one of claims 1 to 5, wherein the first network is a third-generation mobile phone network, and the second network is an IP multimedia subsystem.
The communication system according to claim 6, wherein the speech encoding information notifying unit notifies the speech encoding information based on a session initiation protocol standard.
The resource providing means includes:
A controller that receives the speech coding information related to the terminal from the speech coding information notification means;
A processing unit that encodes audio data by the audio encoding method indicated by the audio encoding information, and transmits the encoded audio data to the terminal;
The communication system according to claim 7, wherein the speech encoded information is transmitted between the control unit and the processing unit based on a standard of a media gateway control protocol.
A communication method of a communication system in which a first network and a second network are connected,
Speech encoded information notifying means included in the first network,
Recognizing a speech encoding method used by a terminal that intends to use the service of the second network via the first network;
Transmitting voice coding information indicating the voice coding method used in the terminal to the second network;
Resource providing means included in the second network includes:
Receiving from the speech coding information notification means speech coding information related to a terminal that intends to use the service of the second network via the first network;
A communication method of transmitting audio data encoded by the audio encoding method indicated by the audio encoding information to the terminal.
Call session control means included in the second network,
Controlling a call session of the terminal to the second network;
In the control of the call session, the speech coding information about the terminal is acquired from the speech coding information notification means,
The communication method according to claim 9, wherein the speech coding information is provided to the resource providing unit.
The interworking means included in the first network connects the terminal to the resource providing means of the first network when the terminal uses the service of the second network. The communication method described in 1.
The communication method according to any one of claims 9 to 11, wherein the voice encoded information notification means is included in a radio network controller existing in the first network.
The communication method according to any one of claims 9 to 11, wherein the voice encoded information notification means is included in a mobile communication switching server existing in the first network.
The communication method according to any one of claims 9 to 13, wherein the first network is a third-generation mobile phone network, and the second network is an IP multimedia subsystem.
15. The communication method according to claim 14, wherein the voice encoding information notifying unit notifies the voice encoding information based on a session initiation protocol standard.
The resource providing means is
A controller that receives the speech coding information related to the terminal from the speech coding information notification means;
A processing unit that encodes audio data by the audio encoding method indicated by the audio encoding information, and transmits the encoded audio data to the terminal;
The communication method according to claim 15, wherein the speech encoded information is transmitted between the control unit and the processing unit based on a standard of a media gateway control protocol.