Patent Publication Number: US-2011071820-A1

Title: Voice-quality evaluating system, communication system, test management apparatus, and test communication apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is related to and is a continuation of U.S. Ser. No. 11/495,692 filed on Jul. 31, 2006 and claims priority to Japanese Patent Application No. 2006-083943, filed on Mar. 24, 2006, incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to a technology for transmitting and receiving voice information for voice-quality test between a test management apparatus and a test communication apparatus and between test communication apparatuses in a network for transmitting and receiving voice packets to perform a voice-call communication. 
     2. Description of the Related Art 
     In recent years, a voice communication system using the Internet has been widespread. In such a voice communication system, since it is possible to build the system at relatively low cost, it is possible to provide a voice communication service inexpensively. 
     It is necessary to perform various tests to measure a voice quality in such a voice communication system. Such tests are called voice quality testing (VQT). As a method for such tests, for example, a voice-quality measuring method capable of measuring an influence that the Internet has on a voice quality by comparing a signal before being input to the Internet and a signal after passing through the Internet is disclosed in Japanese Patent Application Laid-Open No. 2004-297803. 
     Security in the Internet is becoming more and more important. In particular, it is necessary to sort terminal apparatuses, which are permitted to make connection to the Internet, and exclude illegal connection from terminal apparatuses. As such a method, for example, a session-start-protocol system that extends and uses a session initial protocol (SIP) for permitting start of a session (connection) based on a uniform resource indicator (URI) serving as position specifying information for terminals is disclosed in Published Japanese Translation of PCT Patent Application No. 2004-523828. 
     However, in the conventional technology disclosed in Japanese Patent Application Laid-Open No. 2004-297803, in a voice communication system in recent years in which a network is set to allow only a real-time transport protocol (RTP) packet to pass on a transmission path based on a security policy, it is impossible to allow control information for voice quality testing transmitted and received by packets according to a protocol different from the RTP such as a transmission control protocol (TCP) to pass. 
     Therefore, in recent years, in performing voice quality testing in the voice communication system in recent years with a further improved security level, it is necessary to change a structure and setting of the network. This not only causes an increase in work procedures but also cause a problem of deterioration in security. 
     In the conventional technology disclosed in Published Japanese Translation of PCT Patent Application No. 2004-523828, since the extension of the SIP is involved, specifications of conventional apparatuses and networks conforming to the SIP have to be changed. The burden of cost involved in this change poses a problem. 
     Therefore, even if the conventional technologies are combined, it is impossible to exclude connection from terminal apparatuses, which are not permitted to make connection, without changing specifications of the conventional apparatuses and networks and perform voice quality testing without changing a structures and setting of a network of a voice communication system. 
     SUMMARY 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     A voice-quality evaluating system according to one aspect of the present invention, in a secure network that allows a voice packet to pass, transmits and receives communication information for a voice quality testing between a test management apparatus and a test communication apparatus connected to the network and between the test communication apparatuses, for the voice quality testing between the test communication apparatuses arranged on the network. The voice-quality evaluating system embeds the communication information in a payload of the voice packet, and transmits and receives communication-information-embedded voice packet. 
     A communication system according to another aspect of the present invention, in a secure network that allows a voice packet to pass, transmits and receives intersystem communication information between apparatuses connected to the network. The communication system embeds the intersystem communication information in a payload of the voice packet and transmits and receives intersystem-communication-information-embedded voice packet. 
     A test management apparatus according to still another aspect of the present invention manages voice quality testing between test communication apparatuses arranged on a network for transmitting and receiving a voice packet to perform communication for a voice call. The test management apparatus embeds communication information for the voice quality testing in a payload of the voice packet, and transmits communication-information-embedded voice packet. 
     A test communication apparatus according to still another aspect of the present invention is for performing voice quality testing on a network that transmits and receives a voice packet and performs communication for a voice call. The test communication apparatus embeds communication information for the voice quality testing in a payload of the voice packet communication-information-embedded voice packet to other test communication apparatus. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic for illustrating an overview of a problem of a voice evaluation test in a voice-only network; 
         FIG. 2  is a schematic for illustrating an overview of an RTP-packetization of a TCP packet; 
         FIG. 3  is a schematic for illustrating a method of using the RTP packet. 
         FIG. 4  is a schematic for illustrating an overview of the voice evaluation test in the voice-only network according to the present invention; 
         FIG. 5  is a schematic for illustrating a network structure of a voice-evaluation test system in the voice-only network; 
         FIG. 6  is a block diagram of a test management apparatus according to a first embodiment of the present invention; 
         FIG. 7  is a block diagram of a probe according to the first embodiment; 
         FIG. 8  is a sequence diagram of a test-scenario transmission processing according to the first embodiment; 
         FIG. 9  is a sequence diagram of an RTP-test-packet transmission processing according to the first embodiment; 
         FIG. 10  is a sequence diagram of a test-result transmission processing according to the first embodiment; 
         FIG. 11  is a block diagram of a test management apparatus according to a second embodiment of the present invention; 
         FIG. 12  is a block diagram of a probe according to the second embodiment; 
         FIG. 13  is a sequence diagram of a test suspension processing between a test management apparatus and the probe on the test-packet transmission side according to the second embodiment; 
         FIG. 14  is a sequence diagram of a test suspension processing between the probe on the test-packet transmission side and the probe on the test-packet reception side according to the second embodiment; 
         FIG. 15  is a block diagram of a test management apparatus according to a third embodiment of the present invention; 
         FIG. 16  is a block diagram of a probe according to the third embodiment; 
         FIG. 17  is a sequence diagram of a test resumption processing between a test management apparatus and the probe on the test-packet transmission side according to the third embodiment; 
         FIG. 18  is a sequence diagram of a test resumption processing between the probe on the test-packet transmission side and the probe on the test-packet reception side according to the third embodiment; 
         FIG. 19  is a block diagram of a test management apparatus according to a fourth embodiment of the present invention; 
         FIG. 20  is a block diagram of a probe according to the fourth embodiment; 
         FIG. 21  is a sequence diagram of a time synchronization processing according to the fourth embodiment; 
         FIG. 22  is a block diagram of a test management apparatus according to a fifth embodiment of the present invention; 
         FIG. 23  is a block diagram of a probe according to the fifth embodiment; 
         FIG. 24  is a sequence diagram of a firmware update processing according to the fifth embodiment; 
         FIG. 25  is a sequence diagram of an RTP-test-packet partial-retransmission processing according to a sixth embodiment of the present invention; 
         FIG. 26  is a sequence diagram of an RTP-test-packet entire-retransmission processing according to the sixth embodiment; 
         FIG. 27  is a block diagram of a test management apparatus according to a seventh embodiment of the present invention; 
         FIG. 28  is a table concerning the protocol type selection according to the seventh embodiment; 
         FIG. 29  is a flowchart of the protocol selection processing procedure according to the seventh embodiment; 
         FIG. 30  is a block diagram of a test management apparatus according to an eighth embodiment of the present invention; and 
         FIG. 31  is a sequence diagram of an RTP-session-start negotiation processing according to the eighth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of the present invention are explained in detail below with reference to the accompanying drawings. In the embodiments described below, the present invention is applied to a voice-quality evaluating system, a communication system, a test management apparatus, and a test communication apparatus in a network for transmitting and receiving an RTP packet, which is a voice packet, to perform communication for a voice call. The voice packet is not limited to the RTP and may be a packet for generally transmitting voice. 
       FIG. 1  is a schematic for illustrating an overview of a problem of a voice evaluation test in a voice-only network. As shown in the figure, a voice-only network A in which a router A, to which a probe A and an IP telephone A are connected, is arranged and a voice-only network B in which a router B, to which a probe B and an IP telephone B are connected, is arranged are connected to each other with a firewall A as a boundary. A probe is a test communication apparatus and is a measurement base for voice quality evaluation. 
     A test management apparatus (manager) that manages voice quality evaluation performed between the probe A and the probe B is connected to the probe A and the probe B with a firewall B as a boundary. The test management apparatus performs probe control. 
     The voice-only network A and the voice-only network B are voice-only networks for transmitting an RTP packet. Thus, the firewall A permits passage of only the RTP packet and is set not to permit passage of packets of kinds other than the RTP packet. The firewall B only limits passage between the test management apparatus and the probes. Thus, the firewall B is not set to permit passage of only the RTP packet. 
     When voice quality evaluation is performed in such a network, in general, packets different from the RTP packet such as a TCP packet based on socket communication is used for communication information for the voice quality evaluation. Thus, when the network is set as described above, the TCP packet is transmitted and received between the test management apparatus and the probes A and B beyond the firewall B. However, it is impossible to transmit and receive the TCP packet between the probe A and the probe B beyond the firewall A. Therefore, for example, even if a test packet of the TCP packet for the voice quality evaluation is transmitted from the probe A to the probe B, the test packet is blocked by the firewall A. 
     In this way, in a network, transmission and reception of control information is generally performed according to intersystem communication. However, there is a problem in that, when the network is a voice-only network and a transmission path of the intersystem communication permits transmission of only the RTP packet according to a security policy or the like, it is impossible to perform the voice quality evaluation. 
     For example, when a plurality of probes are arranged in a service network zone (an access network and a core router network) of a voice-only network and exchange a test packet among the probes to perform the voice quality evaluation, protocols other than the RTP packet may be regulated according the security policy to prevent illegal access to the core router network. A firewall is arranged in a boundary of the core router network and the access network to prevent packets other than voice packets such as the RTP packet from passing through the firewall. 
     In this case, since measured data at the time of transmission and reception of the test packet is not a voice packet, the measured data is communicated as a TCP packet. However, since the TCP packet cannot pass through the firewall according to the security policy, there is a problem in that it is impossible to perform the voice quality evaluation. The present invention has been devised to solve such a problem and it is an object of the present invention to allow the test packet to pass through the firewall and make it possible to perform the voice quality evaluation. 
     In order to solve the problem illustrated in  FIG. 1 , according to the present invention, RTP-packetization of a TCP packet is performed.  FIG. 2  is a schematic for illustrating an overview of the RTP-packetization of the TCP packet. As shown in the figure, a test packet, which is a TCP packet, is embedded in a payload of a RTP packet to allow various kids of information for voice quality evaluation included in the test packet to pass through a firewall. 
     The TCP packet is a packet obtained by adding TCP control information in front of and behind TCP data. The entire TCP packet is regarded as data and embedded in the payload of the RTP packet. By adding RTP control information in front of and behind the data of the RTP payload, which is the TCP packet, an RTP packet including the various kinds of information for the voice quality evaluation included in the test packet is generated. 
     Although  FIG. 2  is a schematic for explaining the overview of the RTP-packetization of the TCP packet performed according to a first embodiment of the present invention, only the TCP data may be embedded in the payload of the RTP packet without adding the TCP control information. 
       FIG. 3  is a schematic for illustrating a method of using the RTP packet generated by the RTP-packetization of the TCP packet: (a) is a diagram of how to use the RTP packet in an ordinary case; and (b) is a diagram of how to use the RTP packet according to the present invention. 
     As shown in (a) of  FIG. 3 , usually, a voice input subjected to digital conversion by an A/D converter and encoded is RTP-packetized. When this RTP packet is received via a network, the RTP packet is RTP-depacketized according to a procedure opposite to that of the RTP-packetization. This depacketized packet is decoded, subjected to analog conversion by a D/A converter, and output. 
     On the other hand, as shown in (b) of  FIG. 3 , according to the present invention, when TCP data RTP-packetized is received via the network, the RTP packet is RTP-depacketized to extract the TCP data. 
     In this way, the RTP packet handled according to the present invention is characterized in that the RTP packet is not an RTP packet obtained by RTP-packetizing voice but is an RTP packet obtained by RTP-packetizing TCP data, which is originally a TCP packet, and transmitted and received. 
     It is possible to perform a voice evaluation test using the RTP packet obtained by RTP-packetizing the TCP packet as described above.  FIG. 4  is a schematic for illustrating an overview of the voice evaluation test in the voice-only network according to the present invention. As shown in the figure, a voice-only network A  800   a  in which a router A  500 , to which a probe A  200  and an IP telephone A  600   a  are connected, is arranged and a voice-only network B  800   b  in which a router B  500   b , to which a probe B  400  and an IP telephone B  600   b  are connected, is arranged are connected to each other with a firewall A  700   a  as a boundary. 
     A test management apparatus  100  that manages voice quality evaluation performed between the probe A  200  and the probe B  400  is connected to the probe A  200  and the probe B  400  with a firewall B  700   b  as a boundary. 
     Communication of control information between the test management apparatus  100  and the probe A  200  and the probe B  400  is performed using a TCP packet. Since the firewall B  700   b  permits passage of the TCP packet, it is possible to exchange the control information between the test management apparatus  100  and the probe A  200  and the probe B  400  beyond the firewall B. 
     However, the firewall A  700   a  present between the probe A  200  and the probe B  400  is set to permit passage of only an RTP packet without permitting passage of the TCP packet. Therefore, communication of control information between the probe A  200  and the probe B  400  is not performed using the TCP packet. However, by RTP-packetizing the TCP packet as described above, the control information can pass the firewall A  700   a  using the RTP packet. For example, when a test packet RTP-packetized is transmitted from the probe A  200  to the probe B  400 , the probe B  400  receives the test packet, RTP-packetizes a rest result, and returns the test result to the probe A  200 . In this way, it is possible to perform voice quality evaluation between probes arranged in service network zones of voice-only networks. 
     As described above, the voice-quality evaluating system according to the present invention is characterized in that data is embedded in a payload of a voice packet to make it possible to transmit and receive the data even under an environment in which communication of protocols other than a voice packet is regulated according to a security policy. 
       FIG. 5  is a schematic for illustrating a network structure of the voice-evaluation test system in the voice-only network according to the present invention. As shown in the figure, the voice-only network A  800   a  in which the router A  500 , to which the probe A  200  and the IP telephone A  600   a  are connected, is arranged and the voice-only network B  800   b  in which the router B  500   b , to which the probe B  400  and the IP telephone B  600   b  are connected, is arranged are connected to each other with the firewall A  700   a  as a boundary. 
     The test management apparatus  100  that manages voice quality evaluation performed between the probe A  200  and the probe B  400  is connected to the probe A  200  and the probe B  400  with the firewall B  700   b  as a boundary. 
     The test management apparatus  100  performs management of the probes, performs management of a test scenario, performs judgment of a test-packet transmission side probe defined in the test scenario, performs transmission of the test scenario to the probe A  200  serving as the transmission side probe, receives a voice evaluation result from the probe A  200 , and performs storage and management of the voice evaluation result. 
     The probe A  200  receives a test scenario described later from the test management apparatus  100 , transmits test start information (unit of output of a trigger for test start and measured data of a test), transmits a test packet to the probe B  400  based on information defined by the test scenario, receives measured data from the probe B  400 , judges a voice evaluation result based on the measured data received from the probe B  400  and the test scenario, and transmits the voice evaluation result to the test management apparatus  100 . 
     The probe B  400  receives the test start information from the probe A  200 , receives the test packet from the probe A  200 , stores the number of packet losses of the test packet received, a reception interval, and the number of times of reception as measured data, and transmits the measured data stored to the probe A  200 . 
     Moreover, in the voice-only network A  800   a , a session initial protocol (SIP) server  300  is arranged between the test management apparatus  100  and the probe A  200 . The SIP server  300  receives SIP signaling based on a session initial protocol-uniform resource indicator (SIP-URI) indicating positional information of the apparatus and performs communication start negotiation between the test management apparatus  100  and the probe A  200 . The SIP server  300  receives the SIP signaling and performs communication end negotiation between the test management apparatus  100  and the probe A  200 . The SIP signaling is a packet based on the SIP. 
     At least one terminal apparatus  900  is connected to the test management apparatus  100  via a local area network (LAN). The terminal apparatus  900  provides an interface for an operator of a voice-evaluation test system to perform operation of the voice-evaluation test system. Specifically, the interface is a graphical user interface (GUI). The interface is an interface for the operator to register a test scenario, input control for suspension, resumption, and the like of a voice evaluation test, and check a voice evaluation result. 
     In the test scenario, a test section decided by designating a test-packet transmission side probe and a test-packet reception side probe, a test start date and time, a test end date and time, a packet length of a test packet, a transmission interval of the test packet, the number of times of transmission of the test packet, and the like are designated. 
       FIG. 6  is a block diagram of the test management apparatus  100  according to the first embodiment. As shown in the figure, the test management apparatus  100  includes a processing unit  101  that manages control of the test management apparatus  100  and executes various kinds of processing related to a voice evaluation test, a storing unit  102  that stores various kinds of information in advance and stores a voice evaluation result, an RTP-packet generating unit  103  that RTP-packetizes a TCP packet, a TCP-packet extracting unit  104  that extracts a TCP packet from an RTP packet, an RTP-I/F unit  105  that transmits an RTP packet passed from the RTP-packet generating unit  103  to the outside and passes an RTP packet received from the outside to the TCP-packet extracting unit  104 , a SIP-server I/F unit  106  that manages communication between the test management apparatus  100  and the SIP server  300 , and a terminal-apparatus I/F unit  107  that manages communication with the terminal apparatus  900 . 
     The processing unit  101  further includes a reception-permitted SIP-URI information generating unit  101   a  that generates SIP-URI information of apparatuses permitted to receive information from probe information and test management apparatus information stored in the storing unit  102  and transmits the SIP-URI information to the SIP server  300  as required, a SIP-URI reception-permission-judgment processing unit  101   b  that judges, based on information on reception-permitted SIP-URI stored in the storing unit  102 , whether SIP-URI information received from the SIP server  300  is SIP-URI information for permitting reception, a session-start-request processing unit  101   c  that requests the SIP server  300  to start a session with the test-packet transmission side probe, a test-scenario processing unit  101   d  that transmits a test scenario registered from the GUI or stored in the storing unit  102  to the transmission side probe and registers a test scenario received from the test management apparatus  100  in the storing unit  102 , a session-end-request processing unit  101   e  that requests the SIP server  300  to end the session with the transmission side probe, and a test-result receiving unit  101   f  that stores a test result received from the transmission side probe in the storing unit  102  and causes the GUI of the terminal apparatus  900  to display the test result. 
     The storing unit  102  further includes a probe-information storing unit  102   a  that stores probe information, a test-management-apparatus-information storing unit  102   b  that stores test management apparatus information, a reception-permitted SIP-URI storing unit  102   c  that stores a SIP-URI of apparatuses permitted to receive information, a test-scenario storing unit  102   d  that stores a test scenario, and a test-result accumulating unit  102   e  that stores a test result received from a reception side probe of the test packet. 
       FIG. 7  is a block diagram of the probe A  200  according to the first embodiment. As shown in the figure, the probe A  200  includes a processing unit  201  that manages processing of the probe A  200  and executes various kinds of processing related to a voice evaluation test, a storing unit  202  that stores various kinds of information in advance and stores test data, which is measured data of the voice evaluation test, an RTP-packet generating unit  203  that RTP-packetizes a TCP packet, a TCP-packet extracting unit  204  that acquires, when an RTP packet is a test packet, data such as a packet length, a reception interval, and the number of times of reception of the RTP packet as test data and extracts, when an RTP packet is not a test packet, a TCP packet from the RTP packet, an RTP-I/F unit  205  that transmits an RTP packet passed from the RTP-packet generating unit  203  to the outside and passes an RTP packet received from the outside to the TCP-packet extracting unit  204 , and a SIP-server I/F unit  206  that manages communication between the probe A  200  and the SIP server  300 . 
     The processing unit  201  further includes a SIP-URI reception-permission-judgment processing unit  201   a  that judges, based on information on a reception-permitted SIP-URI stored in the storing unit  202 , whether SIP-URI information of the test-packet transmission side probe received from the SIP server  300  is SIP-URI information for permitting reception, a session-start processing unit  201   b  that starts a session with the reception side probe of the test packet based on a session start request from the SIP server  300 , a test-scenario-reception processing unit  201   c  that stores a test scenario received from the SIP server  300  in the storing unit  202 , a test-data-notification processing unit  201   d  that notifies the test-packet transmission side probe of test data stored in the storing unit  202 , a test-result-judgment processing unit  201   e  that judges a test result based on the test data and the test scenario stored in the storing unit  202 , a test-result-notification processing unit  201   f  that notifies the test-packet transmission side probe of a result of the judgment by the test-result-judgment processing unit  201   e , a session-end processing unit  201   g  that ends the session with the reception side probe of the test packet based on a request for session end from the SIP server  300 , a test-data-reception processing unit  201   h  that stores test data received from the reception side probe in the storing unit  202 , and a test executing unit  201   i  that executes a test based on the test scenario stored in the storing unit  202 . 
     The test result judged by the test-result-judgment processing unit  201   e  includes a packet delay, a packet loss, a jitter value, and an R value. 
     The storing unit  202  further includes a reception-permitted SIP-URI storing unit  202   a  that stores a SIP-URI of apparatuses permitted to receive information, a test-scenario storing unit  202   b  that stores a test scenario, and a test-data accumulating unit  202   c  that stores test data received from the reception side probe of the test packet. 
       FIG. 8  is a sequence diagram of the test-scenario transmission processing according to the first embodiment. The probe A  200  is set as a test-packet transmission side probe. As shown in the figure, a test scenario is input from the terminal apparatus  900  (step S 101 ). The processing unit  101  registers the test scenario received via the terminal-apparatus I/F unit  107  of the test management apparatus  100  in the storing unit  102  (step S 102 ). 
     The processing unit  101  determines a test-packet transmission side probe based on the test scenario (step S 103 ) and requests the SIP server  300  to start a session with the transmission side probe (steps S 104  and S 105 ). In response to this request, the SIP server  300  transmits the request to the probe A  200  (step S 106 ) and notifies the test management apparatus  100  that the request is received (step S 107 ). 
     In the probe A  200 , the SIP-URI reception-permission-judgment processing unit  201   a  judges, based on the reception-permitted SIP-URI stored, whether the request is a request from a SIP-URI permitted to receive information (step S 108 ). The SIP-URI reception-permission-judgment processing unit  201   a  transmits information on permission of reception to the test management apparatus  100  through the SIP server  300  (steps S 109  and S 110 ). The test management apparatus  100 , which has received this information on permission of reception, transmits ACK (acknowledgment of session establishment) to the probe A  200  through the SIP server  300  (steps S 111  and S 112 ). 
     The processing unit  101  detects completion of the session start (step S 113 ) and, then, outputs a request for test scenario transmission (step S 114 ). The processing unit  101  RTP-packetizes this test scenario (step S 115 ) and transmits the RTP packet to the probe A  200  (steps S 116  and S 117 ). In the probe A  200 , which has received the test scenario, the test scenario received is transmitted to the TCP-packet extracting unit  204  (step S 118 ). The test scenario RTP-depacketized by the TCP-packet extracting unit  204  is transmitted to the test-scenario-reception processing unit  201   c  (step S 119 ). 
     The test-scenario-reception processing unit  201   c  assembles a test scenario from a sequence of the test scenario received (step S 120 ) and transmits this test scenario to the test executing unit  201   i  (step S 121 ). 
     When the transmission of the test scenario ends, the processing unit  101  detects completion of the test scenario transmission (step S 122 ). Subsequently, the processing unit  101  transmits a request for session end to the probe A  200  through the SIP server  300  (steps S 123 , S 124 , and S 125 ). 
     When the probe A  200  receives the request for session end, the probe A  200  transmits information on permission of session end to the test management apparatus  100  through the SIP server  300  (steps S 126  and S 127 ). Finally, the processing unit  101  detects this information on permission of session end (step S 128 ). When the processing unit  101  detects the session end, the processing unit  101  transmits information on completion of test scenario registration to the terminal apparatus  900  via the terminal-apparatus I/F unit  107  (steps S 129  and S 130 ). In this way, the processing for registering the test scenario in the probe A  200  is completed. 
       FIG. 9  is a sequence diagram of the RTP-test-packet transmission processing according to the first embodiment. The probe A  200  is set as a test-packet transmission side probe and the probe B  400  is set as a test-packet reception side probe. As shown in the figure, the test executing unit  201   i  of the probe A  200  transmits a request for transmission of test start information based the test scenario (step S 131 ). This request for transmission of test start information is RTP-depacketized by the RTP-packet generating unit  203  (step S 132 ). This RTP packet is transmitted to the probe B  400  via the RTP-I/F unit  205  (steps S 133  and S 134 ). 
     The RTP packet received via an RTP-I/F unit  405  is transmitted to a TCP-packet extracting unit  404  (step S 135 ), RTP-depacketized by the TCP-packet extracting unit  404 , and, then, passed to the test-data-reception processing unit  401   b  (step S 136 ). A test-data-reception processing unit  401   h  recognizes start of a test by receiving RTP-depacketized information and acquires a unit of output of test data (step S 137 ). 
     The probe A  200  transmits a request for transmission of RTP test packet (step S 138 ). This request for transmission of RTP test packet is RTP-packetized by the RTP packet generating unit  203  (step S 139 ). This is transmitted to the probe B  400  via the RTP-I/F  2005  (steps S 140  and S 141 ). 
     When the probe B  400  receives a test packet via the RTP-I/F unit  405 , the probe B  400  transmits this reception packet to the TCP-packet extracting unit  404  (step S 142 ). The probe B  400  transmits test data obtained by performing RTP-depacketization of the reception packet in the TCP-packet extracting unit  404  to the test-data-reception processing unit  401   h  (step S 143 ). The processing at steps S 140  to S 143  is repeated by the number of times of test packet transmission defined in the test scenario. In this way, test data is stored in the storing unit  202  of the probe B  400 . 
     To transmit the test data stored in the storing unit  202  of the probe B  400  according to the repetition of the processing at steps S 140  to S 143  to the probe A  200 , the test-data-reception processing unit  401   h  of the probe B  400  issues a request for test data transmission to a test-data-notification processing unit  401   d  (step S 144 ). Based on this request, the test-data-notification processing unit  401   d  reads out the test data stored from the storing unit  202  and transmits the test data (step S 145 ). 
     The test data transmitted from the test-data-notification processing unit  401   d  is RTP-packetized by an RTP-packet generating unit  403  (step S 146 ). This RTP-packetized information is transmitted to the probe A  200  via the RTP-I/F unit  405  (steps S 147  and S 148 ). 
     The probe A  200  transmits the RTP packet received by the RTP-IF unit  205  to the TCP-packet extracting unit  204  (step S 149 ). The TCP-packet extracting unit  204  extracts test data from the RTP packet received according to RTP-depacketization and transmits the test data to the test-result-judgment processing unit  201   e  (step S 150 ). The test-result-judgment processing unit  201   e , which has received the test data, judges a test result from the test data and the test scenario (step S 151 ). A result of this judgment is transmitted to the test-result-notification processing unit  201   f  (step S 152 ), stored in the storing unit  202 , and displayed on the GUI of the terminal apparatus  900 . 
       FIG. 10  is a sequence diagram of the test-result transmission processing according to the first embodiment. The probe A  200  is set as a test-packet transmission side probe. As shown in the figure, to transmit a test result, the test-result-notification processing unit  201   f  of the probe A  200  requests start of a session with the test management apparatus  100  (step S 161 ). This request is transmitted from the SIP-server I/F unit  206  to the test management apparatus  100  through the SIP server  300  (steps S 162  and S 163 ). The session start request is returned to the probe A  200  as well (step S 164 ). 
     In the test management apparatus  100 , when the session start request is received via the SIP-server I/F unit  106 , the SIP-URI reception-permission-judgment processing unit  101   b  judges, based on the reception-permitted SIP-URI stored, whether the session start request is a request from a SIP-URI permitted to receive information (step S 165 ). The SIP-URI reception-permission-judgment processing unit  101   b  transmits information on permission of reception to the probe A  200  through the SIP server  300  (steps S 166  and S 167 ). The probe A  200 , which has received this information on permission of reception, transmits ACK (acknowledgement of session establishment) to the test management apparatus  100  through the SIP server  300  (steps S 168  and S 169 ). 
     The test-result-notification processing unit  201   f  of the probe A  200  detects completion of the session start (step S 170 ) and, then, outputs a request for test result transmission (step S 171 ). The test-result-notification processing unit  201   f  RTP-packetizes this test result (step S 172 ) and transmits the RTP packet to the test management apparatus  100  (steps S 173  and S 174 ). In the test management apparatus  100 , which has received the test result, the test result received is transmitted to the TCP-packet extracting unit  104  (step S 175 ). The test result RTP-depacketized by the TCP-packet extracting unit  104  is transmitted to the test-result receiving unit  101   f  (step S 176 ). In this way, the test result reaches the test management apparatus  100 . 
     When the transmission of the test result ends, the test-result-notification processing unit  201   f  of the probe A  200  detects completion of the test result transmission (step S 177 ). Subsequently, a request for session end is transmitted to the test management apparatus  100  through the SIP server  300  (steps S 178 , S 179 , and S 180 ). 
     When the test management apparatus  100  receives the request for session end, the test management apparatus  100  transmits information on permission of the session end to the probe A  200  through the SIP server  300  (steps S 181  and S 182 ). Finally, the test-result-notification processing unit  201   f  of the probe A  200  detects this information on permission of the session end (step S 183 ). In this way, the processing for transmitting the test result from the probe A  200  to the test management apparatus  100  ends. 
     According to the first embodiment, it possible to transmit and receive, even under an environment in which communication of protocols other than a specific packet is regulated by a security policy, intersystem communication information, which can be transmitted by protocols other than the specific packet, among apparatuses arranged on a network. 
     In particular, the voice-quality evaluating system using the present invention is capable of transmitting and receiving, even under an environment in which protocols other than a voice packet is regulated according to a security policy such as a voice-only network, test result information, test start information, test control information, test scenario information, time synchronization information, and firmware information among apparatuses (the test management apparatus  100 , probes or IP telephones, etc.) arranged on the network. 
     Since it is possible to instruct transmission of a test scenario from a remote location and the probes automatically performs a voice quality evaluation test based on this test scenario, it is possible to control the voice quality evaluation test from the remote location. 
     The invention according to the first embodiment has been devised to solve the following problem. Even when TCP socket communication and HTTP/HTTPS communication are possible, in a system in which there are a plurality of communication objects and relocation and extension of connected apparatuses are frequently performed, setting of a firewall may have to be changed every time dislocation or extension of the communication objects is performed. This is inconvenience in terms of system operation. 
     According to the first embodiment, the voice-quality evaluating system has the SIP server  300  to solve the following problem. The apparatuses that could be a reception side of data (the test management apparatus  100  and the probes) have a transmission path security function using the SIP and a communication function using the RTP packet. Therefore, apparatuses having these functions can start communication even if the apparatuses are not legitimate apparatuses. However, since the apparatuses carry out functions of the voice-quality evaluating system, transmission of data from malicious apparatuses has to be excluded. Accordingly, it is necessary to make it possible to select a transmission side apparatus that is allowed to perform communication. 
     For example, in the voice-quality evaluating system, it is necessary to extend or relocate the probes according to a section in which it is desired to perform a test. The probes notify the test management apparatus  100  of a test result using a TCP socket or HTTP/HTTPS. At the same time, the probes receive a test scenario, latest firmware, and time synchronization information from the test management apparatus  100 . Usually, since the probes are placed in a service network zone (a core router network and an access network), a firewall is placed between the test management apparatus  100  and the probes. 
     Therefore, a TCP port used between the test management apparatus  100  and the probes has to be opened. Setting of the firewall has to be changed to cause the TCP socket to pass through the firewall. This work increases a work load as the number of probes is larger. When the TCP port is opened, more problems of security occur. 
     The invention according to the first embodiment can prevent problems of security from occurring because of opening of the TCP port without requiring a procedure for setting passage permission of a TCP socket in a firewall. Moreover, since a SIP-URI of the transmission side apparatus for data is judged, it is possible to receive only data from legitimate transmission side apparatuses without performing data reception from transmission side apparatuses not permitted to transmit data. 
     A second embodiment of the present invention including a test suspending function is explained with reference to  FIGS. 11 to 14 . A network structure and structures and functions of respective apparatuses according to the second embodiment are identical with those according to the first embodiment except that the test management apparatus  100  and the probe A  200  and the probe B  400  have structures for the test suspending function and perform processing for test suspension. 
       FIG. 11  is a block diagram of the test management apparatus  100  according to the second embodiment. As shown in the figure, the test management apparatus  100  according to the second embodiment further includes a test-suspension processing unit  101   g  in the processing unit  101 . Except this difference, the test management apparatus  100  according to the second embodiment is identical with the test management apparatus  100  according to the first embodiment. 
     The test-suspension processing unit  101   g  transmits an instruction for test suspension to the probes based on a test suspension instruction input from the terminal apparatus  900 . This instruction is RTP-packetized by the RTP-packet generating unit  103  and, then, transmitted to the probes via the RTP-I/F unit  105 . 
       FIG. 12  is a block diagram of the probe A  200  according to the second embodiment. According to the second embodiment, as in the first embodiment, the structure of the probe B  400  is identical with the structure of the probe A  200 . As shown in the figure, the probe A  200  according to the second embodiment further includes a test-suspension processing unit  201   j  in the processing unit  201  of the probe A  200  according to the first embodiment. Except this difference, the probe A  200  according to the second embodiment is identical with the probe A  200  according to the first embodiment. 
     The test-suspension processing unit  201   j  outputs an instruction for test suspension to the test executing unit  201   i  based on a test suspension instruction received from the test management apparatus  100 . This instruction is received from a test-packet transmission side probe via the RTP-I/F unit  205 , depacketized by the RTP-packet extracting unit  204 , and, then, received by the test-suspension processing unit  201   j . The test-suspension processing unit  201   j , which has received this instruction, instructs the test executing unit  201   i  to suspend a test. 
       FIG. 13  is a sequence diagram of the test suspension processing between the test management apparatus  100  and the probe A  200  according to the second embodiment. The probe A  200  is set as a test-packet transmission side probe. As shown in the figure, a test suspension instruction is input from the terminal apparatus  900  (step S 191 ). The test-suspension-processing unit  101   g  detects the test suspension instruction received via the terminal-apparatus I/F unit  107  of the test management apparatus  100  (step S 192 ). 
     The SIP-URI reception-permission-judgment processing unit  101   b  determines a test-packet transmission side probe based on a test scenario (step S 193 ). The SIP-URI reception-permission-judgment processing unit  101   b  requests the SIP server  300  that the session-start-request processing unit  101   c  start a session with the transmission side probe (steps S 194  and S 195 ). In response to this request, the SIP server  300  transmits the request to the probe A  200  (step S 196 ) and notifies the test management apparatus  100  that the request is received (step S 197 ). 
     In the probe A  200 , the SIP-URI reception-permission-judgment processing unit  201   a  judges, based on the reception-permitted SIP-URI stored, whether the request is a request from a SIP-URI permitted to receive information (step S 198 ). The SIP-URI reception-permission-judgment processing unit  201   a  transmits information on permission of reception to the test management apparatus  100  through the SIP server  300  (steps S 199  and S 200 ). The test management apparatus  100 , which has received this information on permission of reception, transmits ACK (acknowledgment of session establishment) to the probe A  200  through the SIP server  300  (steps S 201  and S 202 ). 
     The processing unit  101  of the test management apparatus  100  detects completion of the session start (step S 203 ) and, then, outputs a request for test suspension (step S 204 ). The processing unit  101  RTP-packetizes this test suspension request (step S 205 ) and transmits the RTP packet to the probe A  200  (steps S 206  and S 207 ). In the probe A  200 , which has received the test suspension request, the test suspension request received is transmitted to the TCP-packet extracting unit  204  (step S 208 ). The test suspension request RTP-depacketized by the TCP-packet extracting unit  204  is transmitted to the test-suspension processing unit  201   j  (step S 209 ). The test-suspension processing unit  201   j  passes the test suspension request received to the test executing unit  201   i  (step S 210 ). Test suspension is executed. 
     When the transmission of the test suspension request ends, the processing unit  101  of the test management apparatus  100  detects completion of the test suspension instruction (step S 211 ). Subsequently, the processing unit  101  transmits a request for session end to the probe A  200  through the SIP server  300  (steps S 212 , S 213 , and S 214 ). 
     When the probe A  200  receives the request for session end, the probe A  200  transmits information on permission of the session end to the test management apparatus  100  through the SIP server  300  (steps S 215  and S 216 ). Finally, the processing unit  101  detects this information on permission of the session end (step S 217 ). When the processing unit  101  detects the session end, the processing unit  101  transmits information on completion of the test suspension instruction to the terminal apparatus  900  via the terminal-apparatus I/F unit  107  (steps S 218  and S 219 ). In this way, the processing for transmitting the test suspension instruction to the probe A  200  is completed. 
     The test suspension processing is explained as being executed based on a test suspension instruction of an operator of the voice evaluation system. However, the present invention is not limited to this. Test suspension may be executed in association with a test scenario or the test management apparatus  100  may execute test suspension based on cooperation with other systems. 
       FIG. 14  is a sequence diagram of the test suspension processing between the probe A  200  and the probe B  400  according to the second embodiment. The probe A  200  is set as a test-packet transmission side probe and the probe B  400  is set as a test-packet reception side probe. As shown in the figure, the test-suspension processing unit  201   j  of the probe A  200  transmits a request for test suspension information transmission (step S 221 ). This request for test suspension information transmission is RTP-packetized by the RTP-packet generating unit  203  (step S 222 ). This RTP packet is transmitted to the probe B  400  via the RTP-I/F unit  205  (steps S 223  and S 224 ). 
     The RTP packet including request information for test suspension received via the RTP-I/F unit  405  is transmitted to the TCP-packet extracting unit  404  (step S 225 ), RIP-depacketized by the TCP-packet extracting unit  404 , and, then, passed to a test-suspension processing unit  401   j  (step S 226 ). The test-suspension processing unit  401   j  recognizes the test suspension by receiving the information RTP-depacketized (step S 227 ). Through the processing, transmission of test packets from the probe A  200  to the probe B  400  after that are entirely cancelled. According to the second embodiment, it is possible to instruct test suspension from a remote location. 
     Suspension processing is also possible for a session via the SIP server  300  between the test management apparatus  100  and the probe A  200 . Thus, it is also possible to perform transmission suspension processing in test-scenario transmission processing. 
     In general, the suspension processing is also possible for a session among apparatuses via the SIP server  300 . In other words, the suspension processing is also possible in processing for embedding intersystem communication information in a payload of an RTP packet and transmitting the RTP packet among the apparatuses via the SIP server  300 . Thus, for example, it is also possible to perform the transmission suspension processing in transmission processing for test result information, test start information, test control information, test scenario information, synchronization time information, firmware update information, and the like between the probe A  200  and the probe B  400 . 
     A third embodiment of the present invention including a test resuming function is explained with reference to  FIGS. 15 to 18 . A network structure and structures and functions of respective apparatuses according to the third embodiment are identical with those according to the first embodiment except that the test management apparatus  100  and the probe A  200  and the probe B  400  have structures for the test resuming function and perform processing for test resumption. The test resuming function is used for resuming a test when execution of the test is suspended by a failure or the like or when execution of the test is suspended by an operator of the voice evaluation system as described according to the second embodiment. 
       FIG. 15  is a block diagram of the test management apparatus  100  according to the third embodiment. As shown in the figure, the test management apparatus  100  according to the third embodiment further includes a test-resumption processing unit  101   h  in the processing unit  101  of the test management apparatus  100  according to the first embodiment. Except this difference, the test management apparatus  100  according to the third embodiment is identical with the test management apparatus  100  according to the first embodiment. 
     The test-resumption processing unit  101   h  transmits an instruction for test resumption to probes based on a test resumption instruction input from the terminal apparatus  900 . This instruction is RTP-packetized by the RTP-packet generating unit  103  and, then, transmitted to the probes via the RTP-I/F unit  105 . 
       FIG. 16  is a block diagram of the probe A  200  according to the third embodiment. According to the third embodiment, as in the first and the second embodiments, a structure of the probe B  400  is identical with the structure of the probe A  200 . As shown in the figure, the probe A  200  according to the third embodiment further includes a test-resumption processing unit  201   k  in the processing unit  201  of the probe A  200 . Except this difference, the probe A  200  according to the third embodiment is identical with the probe A  200  according to the first embodiment. 
     The test-resumption processing unit  201   k  outputs an instruction for test resumption to the test executing unit  201   i  based on a test resumption instruction received from the test management apparatus  100 . This instruction is received from a test-packet transmission side probe via the RTP-I/F unit  205 , RTP-depacketized by the RTP-packet extracting unit  204 , and, then, received by the test-resumption processing unit  201   k . The test-resumption processing unit  201   k , which has received this instruction, instructs the test executing unit  201   i  to resume a test. 
       FIG. 17  a sequence diagram of the test resumption processing between the test management apparatus  100  and the probe A  200  according to the third embodiment. The probe A  200  is set as a test-packet transmission side probe. As shown in the figure, first, a test resumption instruction is input from the terminal apparatus  900  (step S 231 ). The test-resumption processing unit  101   h  detects the test resumption instruction received via the terminal-apparatus I/F unit  107  of the test management apparatus  100  (step S 232 ). 
     The SIP-URI reception-permission-judgment processing unit  101   b  determines a test-packet transmission side probe based on a test scenario (step S 233 ) and requests the SIP server  300  that the session-start-request processing unit  101   c  start a session with the transmission side probe (steps S 234  and S 235 ). In response to this request, the SIP server  300  transmits the request to the probe A  200  (step S 236 ) and notifies the test management apparatus  100  that the request is received (step S 237 ). 
     In the probe A  200 , the SIP-URI reception-permission-judgment processing unit  201   a  judges, based on the reception-permitted SIP-URI stored, whether the request is a request from a SIP-URI permitted to receive information (step S 238 ). The SIP-URI reception-permission-judgment processing unit  201   a  transmits information on permission of reception to the test management apparatus  100  through the SIP server  300  (steps S 239  and S 240 ). The test management apparatus  100 , which has received this information on permission of reception, transmits ACK (acknowledgment of session establishment) to the probe A  200  through the SIP server  300  (steps S 241  and S 242 ). 
     The processing unit  101  of the test management apparatus  100  detects completion of the session start (step S 243 ) and, then, outputs a request for test resumption (step S 244 ). The processing unit  101  RTP-packetizes this test resumption request (step S 245 ) and transmits the RTP packet to the probe A  200  (steps S 246  and S 247 ). In the probe A  200 , which has received the test resumption request, the test resumption request received is transmitted to the TCP-packet extracting unit  204  (step S 248 ). The test resumption request RTP-depacketized by the TCP-packet extracting unit  204  is transmitted to the test-resumption processing unit  201   k  (step S 249 ). The test-resumption processing unit  201   k  passes the test resumption request received to the test executing unit  201   i  (step S 250 ), and the test resumption is executed. 
     When the transmission of the test resumption request ends, the processing unit  101  of the test management apparatus  100  detects completion of the test resumption instruction (step S 251 ). Subsequently, the processing unit  101  transmits a request for session end to the probe A  200  through the SIP server  300  (steps S 252 , S 253 , and S 254 ). 
     When the probe A  200  receives the request for session end, the probe A  200  transmits information on permission of the session end to the test management apparatus  100  through the SIP server  300  (steps S 255  and S 256 ). Finally, the processing unit  101  detects this information on permission of the session end (step S 257 ). When the processing unit  101  detects the session end, the processing unit  101  transmits information on completion of the test resumption instruction to the terminal apparatus  900  via the terminal-apparatus I/F unit  107  (steps S 258  and S 259 ). In this way, the processing for transmitting the test resumption instruction to the probe A  200  is completed. 
     The test resumption processing is explained as being executed based on a test resumption instruction of an operator of the voice evaluation system. However, the present invention is not limited to this. Test resumption may be executed in association with a test scenario or the test management apparatus  100  may execute test resumption based on cooperation with other systems. 
       FIG. 18  is a sequence diagram of the test resumption processing between the probe A  200  and the probe B  400  according to the third embodiment. The probe A  200  is set as a test-packet transmission side probe and the probe B  400  is set as a test-packet reception side probe. As shown in the figure, the test-resumption processing unit  201   k  of the probe A  200  transmits a request for test resumption information transmission (step S 261 ). This request for test resumption information transmission is RTP-packetized by the RTP-packet generating unit  203  (step S 262 ). This RTP packet is transmitted to the probe B  400  via the RTP-I/F unit  205  (steps S 263  and S 264 ). 
     The RTP packet including request information for test resumption received via the RTP-I/F unit  405  is transmitted to the TCP-packet extracting unit  404  (step S 265 ), RTP-depacketized by the TCP-packet extracting unit  404 , and, then, passed to a test-resumption processing unit  401   k  (step S 266 ). The test-resumption processing unit  401   k  recognizes the test resumption by receiving the information RTP-depacketized (step S 267 ). 
     The probe A  200  transmits a request for RTP test packet transmission resumption (step S 268 ). This request for RTP test packet transmission resumption is RTP-packetized by the RTP-packet generating unit  203  (step S 269 ). This RTP packet is transmitted to the probe B  400  via the RTP-I/F unit  205  (steps S 270  and S 271 ). 
     When the probe B  400  receives a test packet via the RTP-I/F unit  405 , the probe B  400  transmits this reception packet to the TCP-packet extracting unit  404  (step S 272 ). The probe B  400  transmits test data obtained by performing RTP-depacketization of the reception packet in the TCP-packet extracting unit  404  to the test-resumption processing unit  401   k  (step S 273 ). This processing at steps S 270  to S 273  is repeated by the number of times of test packet transmission defined in the test scenario. In this way, transmission of the test packet suspended is resumed. According to the third embodiment, it is possible to instruct test resumption from a remote location. 
     Resumption processing is also possible for a session via the SIP server  300  between the test management apparatus  100  and the probe A  200 . Thus, it is also possible to perform transmission resumption processing in test-scenario transmission processing. 
     In general, the resumption processing is also possible for a session among apparatuses via the SIP server  300 . In other words, the resumption processing is also possible in processing for embedding intersystem communication information in a payload of an RTP packet and transmitting the RTP packet among the apparatuses via the SIP server  300 . Thus, for example, it is also possible to perform the transmission resumption processing in transmission processing for test result information, test start information, test control information, test scenario information, synchronization time information, firmware update information, and the like between the probe A  200  and the probe B  400 . 
     A fourth embodiment of the present invention including a time synchronizing function is explained with reference to  FIGS. 19 to 21 . A network structure and structures and functions of respective apparatuses according to the fourth embodiment are identical with those in the first embodiment except that the test management apparatus  100  and the probe A  200  and the probe B  400  have structures for the time synchronizing function and perform processing for time synchronization. The time synchronizing function is used for synchronizing system time of apparatuses that could be arranged in the voice evaluation system. 
       FIG. 19  is a block diagram of the test management apparatus  100  according to the fourth embodiment. As shown in the figure, the test management apparatus  100  according to the fourth embodiment further includes a synchronization-time transmitting unit  108  in the test management apparatus  100  according to the first embodiment. Except this difference, the test management apparatus  100  according to the fourth embodiment is identical with the test management apparatus  100  according to the first embodiment. 
     The synchronization-time transmitting unit  108  transmits an instruction for time synchronization to probes based on a time synchronization start instruction input from the terminal apparatus  900 . Prior to transmission of this time synchronization instruction to probes subjected to the time synchronization, session establishment by a SIP via the SIP server  300  is executed. The time synchronization instruction and synchronization time information are RTP-packetized by the RTP-packet generating unit  103  and, then, transmitted to the probes via the RTP-I/F unit  105 . 
       FIG. 20  is a block diagram of the probe A  200  according to the fourth embodiment. According to the fourth embodiment, as in the first to the third embodiments, a structure of the probe B  400  is identical with the structure of the probe A  200 . As shown in the figure, the probe A  200  according to the fourth embodiment further includes a synchronization-time receiving unit  201   i  and a time setting unit  201   m  in the processing unit  201  of the probe A  200 . Except this difference, the probe A  200  according to the fourth embodiment is identical with the probe A  200  according to the first embodiment. 
     The synchronization-time receiving unit  201   l  outputs an instruction for time synchronization to the time setting unit  201   m  based on a time synchronization instruction received from the test management apparatus  100 . This instruction is received from a test-packet transmission side probe via the RTP-I/F unit  205 , RTP-depacketized by the RTP-packet extracting unit  204 , and, then, received by the synchronization-time receiving unit  201   l . The synchronization-time receiving unit  201   l , which has received this instruction, instructs the time setting unit  201   m  to synchronize system time. 
       FIG. 21  is a sequence diagram of the time synchronization processing between the test management apparatus  100  and the probe A  200  according to the fourth embodiment. The probe A  200  is set as a test-packet transmission side probe. As shown in the figure, first, an instruction for time synchronization start is input from the terminal apparatus  900  (step S 281 ). The synchronization-time transmitting unit  108  recognizes the synchronization time information received via the terminal-apparatus I/F unit  107  of the test management apparatus  100  (step S 282 ). 
     The synchronization-time transmitting unit  108  determines a transmission destination probe of the synchronization time information (step S 283 ) and requests the SIP server  300  to start a session with the transmission destination probe (steps S 284  and S 285 ). In response to this request, the SIP server  300  transmits the request to the probe A  200  (step S 286 ) and notifies the test management apparatus  100  that the request is received (step S 287 ). 
     In the probe A  200 , the SIP-URI reception-permission-judgment processing unit  201   a  judges, based on the reception-permitted SIP-URI stored, whether the request is a request from a SIP-URI permitted to receive information (step S 288 ). The SIP-URI reception-permission-judgment processing unit  201   a  transmits information on permission of reception to the test management apparatus  100  through the SIP server  300  (steps S 289  and S 290 ). The test management apparatus  100 , which has received this information on permission of reception, transmits ACK (acknowledgment of session establishment) to the probe A  200  through the SIP server  300  (steps S 291  and S 292 ). 
     The processing unit  101  of the test management apparatus  100  detects completion of the session start (step S 293 ) and, then, outputs a request for synchronization time information transmission (step S 294 ). The processing unit  101  RTP-packetizes this synchronization time information (step S 295 ) and transmits the RTP packet to the probe A  200  (steps S 296  and S 297 ). In the probe A  200 , which has received the synchronization time information, the synchronization time information received is transmitted to the TCP-packet extracting unit  204  (step S 298 ). The synchronization time information RTP-depacketized by the TCP-packet extracting unit  204  is transmitted to the synchronization-time receiving unit  201   l  (step S 299 ). 
     The synchronization-time receiving unit  201   l  transmits the synchronization time information received to the time setting unit  201   m  (step S 300 ). The time setting unit  201   m  updates system time of the probe A  200  based on this synchronization time information (step S 301 ). 
     When the transmission of the synchronization time information ends, the synchronization-time transmitting unit  108  of the test management apparatus  100  detects completion of the synchronization time information transmission (step S 302 ). Subsequently, the synchronization-time transmitting unit  108  transmits a request for session end to the probe A  200  through the SIP server  300  (steps S 303 , S 304 , and S 305 ). 
     When the probe A  200  receives the request for session end, the probe A  200  transmits information on permission of the session end to the test management apparatus  100  through the SIP server  300  (steps S 306  and S 307 ). Finally, the synchronization-time transmitting unit  108  detects this information on permission of the session end (step S 308 ). When the synchronization-time transmitting unit  108  detects the session end, the synchronization-time transmitting unit  108  transmits information on completion of the test resumption instruction to the terminal apparatus  900  via the terminal-apparatus I/F unit  107  (steps S 309  and S 310 ). In this way, the processing for system time synchronization with the probe A  200  of the test management apparatus  100  is completed. According to the fourth embodiment, it is possible to perform processing for system time synchronization from a remote location. 
     A fifth embodiment of the present invention including a firmware update function is explained with reference to  FIGS. 22 to 24 . A network structure and structures and functions of respective apparatuses according to the fifth embodiment are identical with those in the first embodiment except that the test management apparatus  100  and the probe A  200  and the probe B  400  have structures for the firmware update function and perform processing for firmware update. The firmware update function is used for performing update of firmware that controls operations of apparatuses arranged in the voice evaluation system. 
       FIG. 22  is a block diagram of the test management apparatus  100  according to the fifth embodiment. As shown in the figure, the test management apparatus  100  according to the fifth embodiment further includes a firmware-update-information transmitting unit  109  in the processing unit  101  of the test management apparatus  100  according to the first embodiment. Except this difference, the test management apparatus  100  according to the fifth embodiment is identical with the test management apparatus  100  according to the first embodiment. 
     The firmware-update-information transmitting unit  109  transmits an instruction for firmware update to probes based on a firmware update start instruction input from the terminal apparatus  900 . Prior to transmission of this firmware update instruction to probes subjected to firmware update, session establishment by a SIP via the SIP server  300  is executed. The firmware update instruction and firmware update information are RTP-packetized by the RTP-packet generating unit  103  and, then, transmitted to the probes via the RTP-I/F unit  105 . 
       FIG. 23  is a block diagram of the probe A  200  according to the fifth embodiment. According to the fifth embodiment, as in the first to the fourth embodiments, a structure of the probe B  400  is identical with the structure of the probe A  200 . As shown in the figure, the probe A  200  according to the fifth embodiment further includes a firmware-update-information receiving unit  201   n  and a firmware-update processing unit  201   o  in the processing unit  201  of the probe A  200 . Except this difference, the probe A  200  according to the fifth embodiment is identical with the probe A  200  according to the first embodiment. 
     The firmware-update-information receiving unit  201   n  outputs an instruction for firmware update to the firmware-update processing unit  201   o  based on a firmware update instruction received from the test management apparatus  100 . This instruction is received from a test-packet transmission side probe via the RTP-I/F unit  205 , RTP-depacketized by the RTP-packet extracting unit  204 , and, then, received by the firmware-update-information receiving unit  201   n . The firmware-update-information receiving unit  201   n , which has received this instruction, instructs the firmware-update processing unit  201   o  to update firmware stored in a firmware storing unit  202   d  of the storing unit  202 . 
       FIG. 24  is a sequence diagram of the firmware update processing between the test management apparatus  100  and the probe A  200  according to the fifth embodiment. The probe A  200  is set as a test-packet transmission side probe. As shown in the figure, first, a firmware update start instruction is input from the terminal apparatus  900  (step S 311 ). The firmware-update-information transmitting unit  109  recognizes firmware update information received via the terminal-apparatus I/F unit  107  of the test management apparatus  100  (step S 312 ). 
     The firmware-update-information transmitting unit  109  determines an update object probe (step S 313 ) and requests the SIP server  300  to start a session with the update object probe (steps S 314  and S 315 ). In response to this request, the SIP server  300  transmits the request to the probe A  200  (step S 316 ) and notifies the test management apparatus  100  that the request is received (step S 317 ). 
     In the probe A  200 , the SIP-URI reception-permission-judgment processing unit  201   a  judges, based on the reception-permitted SIP-URI stored, whether the request is a request from a SIP-URI permitted to receive information (step S 318 ). The SIP-URI reception-permission-judgment processing unit  201   a  transmits information on permission of reception to the test management apparatus  100  through the SIP server  300  (steps S 319  and S 320 ). The test management apparatus  100 , which has received this information on permission of reception, transmits ACK (acknowledgment of session establishment) to the probe A  200  through the SIP server  300  (steps S 321  and S 322 ). 
     The processing unit  101  of the test management apparatus  100  detects completion of the session start (step S 323 ) and, then, outputs a request for firmware update information resumption (step S 324 ). The processing unit  101  RTP-packetizes this firmware update information (step S 325 ) and transmits the RTP packet to the probe A  200  (steps S 326  and S 327 ). In the probe A  200 , which has received the firmware update information, the firmware update information received is transmitted to the TCP-packet extracting unit  204  (step S 328 ). The firmware update information RTP-depacketized by the TCP-packet extracting unit  204  is transmitted to the firmware-update-information receiving unit  201   n  (step S 329 ). 
     The firmware-update-information receiving unit  201   n  transmits the firmware update information received to the firmware-update-processing unit  201   o  (step S 330 ). The firmware-update processing unit  201   o  updates the firmware of the probe A  200  based on this firmware update information (step S 331 ). 
     When the transmission of the firmware update information ends, the firmware-update-information transmitting unit  109  of the test management apparatus  100  detects completion of the firmware update information transmission (step S 332 ). Subsequently, the firmware-update-information transmitting unit  109  transmits a request for session end to the probe A  200  through the SIP server  300  (steps S 333 , S 334 , and S 335 ). 
     When the probe A  200  receives the request for session end, the probe A  200  transmits information on permission of the session end to the test management apparatus  100  through the SIP server  300  (steps S 336  and S 337 ). Finally, the firmware-update-information transmitting unit  109  detects this information on permission of the session end (step S 338 ). When the firmware-update-information transmitting unit  109  detects the session end, the firmware-update-information transmitting unit  109  transmits information on the end of the firmware update to the terminal apparatus  900  via the terminal-apparatus I/F unit  107  (steps S 339  and S 340 ). In this way, the processing for updating the firmware of the probe A  200  is completed. According to the fifth embodiment, it is possible to perform processing for updating firmware from a remote location. 
     A sixth embodiment of the present invention including an RTP packet retransmitting function is explained with reference to  FIGS. 25 and 26 . A network structure and structures and functions of respective apparatuses according to the sixth embodiment are identical with those in the first embodiment except that the RTP-packet generating unit  203  (or the RTP-packet generating unit  403 ) and the TCP-packet extracting unit  204  (or the TCP-packet extracting unit  404 ) of the probe A  200  (or the probe B  400 ) perform processing for the RTP-packet retransmitting function. According to the sixth embodiment, the probe A  200  is set as a test-packet transmission side probe and the probe B  400  is set as a test-packet reception side probe. 
       FIG. 25  is a sequence diagram of the RTP-packet-partial-retransmission processing according to the sixth embodiment. The RTP-packet generating unit  203  of the probe A  200  RTP-packetizes a test packet (step S 341 ) and transmits this RTP packet to the probe B  400  via the RTP-I/F unit  205  (steps S 342  and S 343 ). 
     In the probe B  400 , which has received the RTP packet via the RTP-I/F unit  405 , this reception packet is transmitted to the TCP-packet extracting unit  404  (step S 344 ). The TCP-packet extracting unit  404  judges whether there is a loss of data from order information of an RTP packet header of the reception packet (step S 345 ). When it is judged that there is a loss of data, the TCP-packet extracting unit  404  transmits a retransmission request for a lost sequence to the probe A  200  via the RTP-I/F unit  405  (steps S 346  and S 347 ). 
     In the probe A  200 , which has received the lost sequence transmission request via the RTP-I/F unit  205 , the request received is transmitted to the RTP-packet generating unit  203  (step S 348 ). Based on this request, the RTP-packet generating unit  203  transmits (retransmits) the relevant RTP packet to the probe B  400  (steps S 349  and S 350 ). In the probe B  400 , which has received the RTP packet retransmitted, the reception packet is transmitted to the TCP-packet extracting unit  404  (step S 351 ). The TCP-packet extracting unit  404  reassembles data (step S 352 ). In this way, when a loss of a packet occurs, the lost packet is retransmitted and reception data is reassembled. 
       FIG. 26  is a sequence diagram of the RTP-packet-entire-retransmission processing according to the sixth embodiment. First, the RTP-packet generating unit  203  of the probe A  200  RTP-packetizes a test packet (step S 361 ) and transmits this RTP packet to the probe B  400  via the RTP-I/F unit  205  (steps S 362  and S 363 ). 
     In the probe B  400 , which has received the RTP packet via the RTP-I/F unit  405 , this reception packed is transmitted to the TCP-packet extracting unit  404  (step S 364 ). The TCP-packet extracting unit  404  judges whether there is a loss of data from order information of an RTP packet header of the reception packet (step S 365 ). When it is judged that there is a loss of data, the TCP-packet extracting unit  404  transmits a retransmission request of the entire data to the probe A  200  via the RTP-I/F unit  405  (steps S 366  and S 367 ). 
     In the probe A  200 , which has received the entire data retransmission request via the RTP-I/F unit  205 , the request received is transmitted to the RTP-packet generating unit  203  (step S 368 ). Based on this request, the RTP-packet generating unit  203  RTP-packetizes relevant data and retransmits the data to the probe B  400  (steps S 369  and S 370 ). In the probe B  400 , which has received this data retransmitted, the reception data is transmitted to the TCP-packet extracting unit  404  (step S 371 ). In this way, when a loss of a packet occurs, entire data is retransmitted. According to the sixth embodiment, when there is a loss of a reception RTP packet, it is possible to automatically perform retransmission processing for an RTP packet including a lost sequence or entire data. In particular, when only the lost sequence is retransmitted, it is possible to realize retransmission without increasing a load on a network. When the lost sequence occurs, in retransmitting an RTP packet including the entire data, it is possible to implement a retransmitting function with a simple mechanism without the necessity of processing for reassembling a packet. 
     The retransmitting function described according to the sixth embodiment is devised to solve the following problem. When a TCP packet is embedded in an RTP payload and transmitted and received, in general, an RTP is implemented on a user datagram protocol (UDP) to maintain a real time property. However, the UDP does not have the retransmitting function for a packet. Therefore, the RTP does not have the retransmitting function. This means that, since data that should originally be transmitted and received by a TCP having the retransmitting function is RTP-packetized, there is an inconvenience that the retransmitting function is lost. It is necessary to give the retransmitting function to the RTP as well to maintain reliability of communication. 
     Therefore, according to the sixth embodiment, it is possible to improve reliability of communication between the test management apparatus  100  and the probes or between the probes. It is possible to implement the retransmitting function described according to the sixth embodiment not only in the RTP but also in a communication protocol in general that does not originally have the retransmitting function. 
     A seventh embodiment of the present invention including a protocol selecting function is explained with reference to  FIGS. 27 to 29 . A network structure and structures and functions of respective apparatuses according to the seventh embodiment are identical with those in the first embodiment except that the session-start-request processing unit  101   c  performs processing for the protocol selecting function and the storing unit  102  further includes a protocol management table  102   f . According to the seventh embodiment, the test management apparatus  100  selects a communication protocol in making connection to the probe A  200 . 
       FIG. 27  is a block diagram of the test management apparatus  100  according to the seventh embodiment. As shown in the figure, in the test management apparatus  100  according to the seventh embodiment, the storing unit  102  of the test management apparatus  100  according to the first embodiment further includes the protocol management table  102   f . In the test management apparatus  100  according to the seventh embodiment, the session-start-request processing unit  101   c  of the test management apparatus  100  according to the first embodiment further includes a function for the protocol selecting function. Except this difference, the test management apparatus  100  according to the seventh embodiment is identical with the test management apparatus  100  according to the first embodiment. 
     The session-start-request processing unit  101   c  preferentially selects a communication protocol for connection to the probes based on a connection protocol type for each of the probes stored in the protocol management table. When it is impossible to make connection based on the connection protocol type for each of the probes stored in the protocol management table  102   f  or when there is no storage of the connection protocol type for each of the probes, the session-start-request processing unit  101   c  sequentially attempts connection based on respective communication protocols based on a predetermined protocol type selection order. 
       FIG. 28  is a table concerning the protocol type selection according to the seventh embodiment. As shown in (a) of  FIG. 28 , a priority of communication protocols for sequentially attempting connection is in an order of, for example, a protocol (1) (a TCP socket), a protocol (2) (HTTP) and a protocol (3) (SIP+RTP). This priority is only an example. It is possible to change the priority taking into account convenience of system operation. The priority of communication protocols may be changeable at any time according to operation by a system operator. 
     A table (b) of  FIG. 28  is a table image of the protocol management table  102   f . As shown in the figure, a communication protocol type of communication with the test management apparatus  100  is stored in the protocol management table  102   f  for each of the probes. For example, the probe A is stored as the protocol (1), the probe B is stored as the protocol (2), and the probe C is stored as the protocol (3). Communication protocols of communication with the respective probes are selected based on this storage. Communication protocols of session connection between the test management apparatus  100  and the respective probes are managed based on the storage of the protocol management table  102   f.    
     A protocol selection processing procedure performed when it is impossible to make connection based on the connection protocol type for each of the probes stored in the protocol management table  102   f  or when there is no storage of the connection protocol type for each of the probes is explained.  FIG. 29  is a flowchart of the protocol selection processing procedure according to the seventh embodiment. 
     First, in starting a session with a probe X serving as a connection destination probe, the test management apparatus  100  judges whether it is possible to start the session with the protocol (1) (step S 381 ). When it is possible to start the session with the protocol (1) (“Yes” at step S 381 ), the test management apparatus  100  shifts the processing to step S 386 . When it is impossible to start the session with the protocol (1) (“No” at step S 381 ), the test management apparatus  100  shifts the processing to step S 382 . 
     At step S 382 , in starting the session with the probe X, the test management apparatus  100  judges whether it is possible to start the session with the protocol (2) (step S 382 ). When it is possible to start the session with the protocol (2) (“Yes” at step S 382 ), the test management apparatus  100  shifts the processing to step S 386 . When it is impossible to start the session with the protocol 82) (“No” at step S 382 ), the test management apparatus  100  shifts the processing to step S 383 . 
     At step S 383 , in starting the session with the probe X, the test management apparatus  100  judges whether it is possible to start the session with the protocol (3) (step S 383 ). When it is possible to start the session with the protocol (3) (“Yes” at step S 383 ), the test management apparatus  100  shifts the processing to step S 386 . When it is impossible to start the session with the protocol (3) (“No” at step S 383 ), the test management apparatus  100  shifts the processing to step S 384 . 
     At step S 384 , the test management apparatus  100  judges whether the processing at steps S 381  to S 383  has been retried a predetermined number of times (step S 384 ). When it is judges that the processing has been retried the predetermined number of times (“Yes” at step S 384 ), the test management apparatus  100  checks a connection environment between the probe X and the test management apparatus  100  (step S 385 ). When it is not judged that the processing has been retried the predetermined number of times (“No” at step S 384 ), the test management apparatus  100  shifts the processing to step S 381 . On the other hand, at step S 386 , the test management apparatus  100  registers the protocol type, with which it is possible to start the session, in the protocol management table  102   f . The protocol selection processing is completed. According to the seventh embodiment, it is possible to automatically select a communication protocol between the test management apparatus  100  and the probes. Moreover, by storing the communication protocol selected, it is possible to quickly perform session establishment after that. 
     The invention according to the seventh embodiment has been devised to solve the following problem. Because of a structure of a network, a firewall set to allow a communication protocol different from the RTP such as the TCP or the HTTP/HTTPS to pass even if the SIP+RTP is not used may be present. The TCP or the HTTP/HTTPS could be a communication protocol for data communication. Even in such cases, the system needs to prevent occurrence of a problem due to a setting mistake of security by automatically selecting an optimum protocol. 
     An eighth embodiment of the present invention including an RTP session start negotiation function is explained with reference to  FIGS. 30 and 31 . A network structure and structures and functions of respective apparatuses according to the eighth embodiment are identical with those in the first embodiment except that the processing unit  101  of the test management apparatus  100  further includes a session-start-negotiation processing unit  101   i . According to the eighth embodiment, the probe A  200  is set as a test-packet transmission side probe. 
       FIG. 30  is a block diagram of the test management apparatus  100  according to the eighth embodiment. As shown in the figure, in the test management apparatus  100  according to the eighth embodiment, the processing unit  101  of the test management apparatus  100  according to the first embodiment further includes the session-start-negotiation processing unit  101   i . Except this difference, the test management apparatus  100  according to the eighth embodiment is identical with the test management apparatus  100  according to the first embodiment. 
     Prior to RTP packet transmission to the probe A  200 , the session-start-negotiation processing unit  101   i  transmits a data transmission start request to the probe A  200 . The session-start-negotiation processing unit  101   i  performs RTP packet transmission only when OK is returned from the probe A  200  in response to this request. When OK is not returned from the probe A  200  in response to the data transmission start request, the session-start-negotiation processing unit  101   i  instructs the session-end-request processing unit  101   e  to request the end of a session. 
       FIG. 31  is a sequence diagram of the session-start-negotiation processing between the test management apparatus  100  and the probe A  200  according to the eighth embodiment. The probe A  200  is set as a test-packet transmission side probe. It is possible to apply the present invention not only to the test-scenario-transmission processing but also to all kinds of RTP packet communication. As shown in the figure, first, the terminal apparatus  900  inputs a test scenario (step S 391 ). The processing unit  101  registers the test scenario received via the terminal-apparatus I/F unit  107  of the test management apparatus  100  in the storing unit  102  (step S 392 ). 
     The test-scenario processing unit  101   d  determines a test-packet transmission side probe based on the test scenario (step S 393 ) and requests the SIP server  300  to start a session with the transmission side probe (steps S 394  and S 395 ). In response to this request, the SIP server  300  transmits the request to the probe A  200  (step S 396 ) and notifies the test management apparatus  100  that the request is received (step S 397 ). 
     In the probe A  200 , the SIP-URI reception-permission-judgment processing unit  201   a  judges, based on the reception-permitted SIP-URI stored, the request is a request from a SIP-URI permitted to receive information (step S 398 ). The SIP-URI reception-permission-judgment processing unit  201   a  transmits information on permission of reception to the test management apparatus  100  through the SIP server  300  (steps S 399  and S 400 ). The test management apparatus  100 , which has received this information on permission of reception, transmits ACK (acknowledgement of session establishment) to the probe A  200  through the SIP server  300  (steps S 401  and S 402 ). 
     The processing unit  101  of the test management apparatus  100  detects completion of the session start (step S 403 ) and, then, outputs a test scenario transmission request (step S 404 ). The processing unit  101  RTP-packetizes this test scenario (step S 405 ) and transmits the RTP packet to the RTP-I/F unit  105  (step S 406 ). Prior to transmitting this RTP-packetized test scenario to the probe A  200 , the processing unit  101  transmits a data communication start request to the probe A  200  (step S 407 ). If data communication may be started in response to this data communication start request, information on permission of data communication start is transmitted from an RTP-I/F unit  409  of the probe A  200  to the test management apparatus  100  (step S 408 ). When it is not judged that OK at S 408  has arrived, the test management apparatus  100  transmits a session disconnection request to the probe A  200 . 
     When the information on permission of data communication start has arrived at the test management apparatus  100 , the processing unit  101  transmits the RTP-packetized test scenario to the probe A  200  (steps S 409  and S 410 ). In the probe A  200 , which has received the test scenario, the test scenario received is transmitted to the TCP-packet extracting unit  204  (step S 410 ). The test scenario RTP-depacketized by the TCP-packet extracting unit  204  is transmitted to the test-scenario-reception processing unit  201   c  (step S 411 ). 
     The test-scenario-reception processing unit  201   c  assembles a test scenario from a sequence of the test scenario received (step S 412 ) and transmits this test scenario to the text executing unit  201   i  (step S 413 ). 
     When the transmission of the test scenario ends, the processing unit  101  of the test management apparatus  100  detects completion of the test scenario transmission (step S 414 ). Subsequently, the processing unit  101  transmits a session end request to the probe A  200  through the SIP server  300  (steps S 415 , S 416 , and S 417 ). 
     When the probe A  200  receives the session end request, the probe A  200  transmits information on permission of session end to the test management apparatus  100  through the SIP server  300  (steps S 418  and S 419 ). Finally, the processing unit  101  detects this information on permission of session end (step S 420 ). When the processing unit  101  detects the session end, the processing unit  101  transmits information on completion of test scenario registration to the terminal apparatus  900  via the terminal-apparatus I/F unit  107  (steps S 421  and S 422 ). By executing steps S 407  and S 408  between step S 406  and S 409 , when a transmission destination is wrong when an RTP packet is transmitted to the probe A  200 , it is possible to adopt, as voice data, a bit configuration that does not cause noise to smoothly end a session without causing noise. 
     The invention according to the eighth embodiment has been devised to solve the following problem. When test data is transmitted to an apparatus that could be a reception side probe of the test data but is a wrong apparatus and, in particular, when the apparatus is an IP telephone, the test data is converted into voice data in this IP telephone. Since this voice data is not the original voice data, it is possible that the voice data reaches a receiver as noise. It is necessary to prevent such an accident and smoothly end operation. 
     As control information RTP-packetized and transmitted according to the first to the eighth embodiments, there are a test result, test start information, test control information (test suspension information, test resumption information, etc.), test scenario information, test end information, time synchronization information, firmware update information, and the like. However, the control information is not limited to these pieces of information. 
     According to the first to the eighth embodiments, as an example of application of the present invention, the voice quality evaluation test is described. However, it is possible to apply the present invention not only to the voice quality evaluation test but also to a node failure detection test, a communication test, a loop-back test, and the like. 
     According to the first to the eighth embodiments, the present invention is applied to the voice-quality evaluating system in which the test management apparatus  100 , the probes, and the SIP server  300  are arranged. However, it is possible to apply the present invention not only to the voice-quality evaluating system but also to a communication system in general for performing communication using a voice packet in which communication apparatuses other than the test management apparatus  100 , the probes, and the SIP server  300  are arranged. An RTP packet is used as a voice packet. However, it is possible to apply the present invention not only to the RTP packet but also to a voice packet in general. Moreover, intersystem communication control data is transmitted and received using a TCP packet. However, it is possible to apply the present invention not only to this TCP packet but also to a protocol in general that is capable of transmitting and receiving control data. 
     The first to the eighth embodiments have been explained. However, the present invention is not limited to these embodiments and may be carried out in more various different embodiments within the scope of the technical idea described in claims. Naturally, it is possible to simultaneously implement the first to the eighth embodiments. Effects of the present invention are not limited to the effects described in the first to the eighth embodiments. 
     According to an embodiment of the present invention, in the voice-quality evaluating system on the network for transmitting and receiving a voice packet, communication information for voice quality testing is embedded in a payload of the voice packet and transmitted and received. Thus, it is possible to easily perform the voice quality testing without changing a structure and setting of the network. 
     Furthermore, according to an embodiment of the present invention, in the voice-quality evaluating system on the network for transmitting and receiving a voice packet, a test scenario for voice quality testing is embedded in a payload of the voice packet and transmitted and received. Thus, it is possible to easily transmit and receive the test scenario without changing a structure and setting of the network. 
     Moreover, according to an embodiment of the present invention, the transmission path securing apparatus checks the connection source apparatus and secures a transmission path from the connection source apparatus to the connection destination apparatus. Moreover, communication information for securing the transmission path is embedded in a payload of a voice packet and transmitted and received. Thus, it is possible to easily secure a transmission path with the connection source apparatus checked. 
     Furthermore, according to an embodiment of the present invention, in the communication system that transmits and receives intersystem information on the network for transmitting and receiving a voice packet, the intersystem information is embedded in a payload of the voice packet and transmitted and received. Thus, it is possible to easily transmit and receive the intersystem information without changing a structure and setting of the network. 
     Moreover, according to an embodiment of the present invention, in the network in which a plurality of communication protocols are used jointly, it is possible to automatically select an optimum communication protocol and it is possible to prevent a mistake in setting a protocol and exclude connection by protocols, which are not permitted to make connection, to maintain security. 
     Furthermore, according to an embodiment of the present invention, in the communication system that transmits and receives intersystem information on a network for transmitting and receiving an RTP packet, the intersystem information is embedded in a payload of the RTP packet and transmitted and received. Thus, it is possible to easily transmit and receive the intersystem information without changing a structure and setting of the network. 
     Moreover, according to an embodiment of the present invention, when a lost sequence occurs, retransmission of an RTP packet including the lost sequence or the entire data is requested. Thus, it is possible to improve reliability of communication. 
     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.