KR20060088257A - Push to talk system for providing multimedia messaging service in communication system and management method thereof - Google Patents

Abstract

The present invention relates to a PTT system for providing an MMS service in a communication system and an operation method thereof. The PTT system according to the present invention provides an access network for initial access of the PoC client and the PoC client. Stores and manages the SIP / IP core that performs session establishment processing upon call setup request and the location information of GLMS and oC clients that transmit the list to the PoC server when needed by storing and managing individual and group lists for the PoC client. The PoC server transmitting and receiving the actual media between the PreCence server and the PoC client and temporarily buffering the media, if necessary, or when the calling party's PTT subscriber is needed or a specific receiver is selected from the receiving PTT subscriber. If the data of the PTT subscriber is not received, the data is stored separately. It characterized by configured by comprising a D-MMS (Dispatch- Multimedia Messaging Service). In the PTT service method according to the present invention, a first step in which a calling PoC client transmits a predetermined message to a PoC server for call setup to a specific group and an individual, and the PoC server receiving the predetermined message is a called PoC client. A second process of transmitting the message to the PoC client and waiting for an acknowledgment message, and if the PoC server receives a Decline message from the destination PoC client, requests for storage from the D-MMS unit; A third process of transmitting and receiving a response signal, a fourth process of the D-MMS storing transmission data from the originating PoC client, and a fifth process of the D-MMS transmitting the stored data to the destination PoC client Characterized by including the process. Since the present invention includes a D-MMS unit in the conventional PTT service, when a caller leaves urgent or important data, a receiver who does not receive the data can be received later, thereby providing a more reliable service.

PTT, PoC, GLMS, D-MMS

Description

PITITY SYSTEM AND MANAGEMENT METHOD PROVIDEING MULTI-MESSING SERVICES IN COMMUNICATION SYSTEMS {PUSH TO TALK SYSTEM FOR PROVIDING MULTIMEDIA MESSAGING SERVICE IN COMMUNICATION SYSTEM AND MANAGEMENT METHOD THEREOF}             

1 is a block diagram showing a configuration of a PTT system according to the present invention

2 is a signal flow diagram illustrating signal processing when a called party is not available in a PTT direct call according to the first embodiment of the present invention.

3 is a signal flow diagram illustrating signal processing according to a case in which a called party has previously set a call rejection function according to a second embodiment of the present invention.

4 is a signal flow diagram illustrating signal processing when a called party rejects a call according to a third embodiment of the present invention.

5 is a signal flow diagram illustrating signal processing according to a case in which a caller wants to directly connect to a called party's D-MMS according to a fourth embodiment of the present invention.

6 is a signal flow diagram illustrating signal processing according to a case where a specific subscriber is turned off or in a shadow area in a PTT group call according to a fifth embodiment of the present invention.

7 is a signal flow diagram illustrating signal processing according to a case in which a caller directly connects to a D-MMS part of a group in a PTT group call according to the sixth embodiment of the present invention.

The present invention relates to a messaging method and system therefor, and more particularly to a voice messaging system and method in a mobile communication system.

In general, a mobile communication system is a system developed to enable users to perform a call without restriction of a wired line. Therefore, the subscribers of the mobile communication system can carry the call anytime and anywhere while carrying the terminal. Such calls are based on voice calls, and have reached the stage of providing data communication due to the rapid development of mobile communication system and the needs of users. Next, the type of data communication provided by the mobile communication system will be briefly described.

The simplest form of data communication is the short message service. The short message service is a system that delivers a text message input by a calling user to a called terminal through a messaging system. In addition, there is a high speed multimedia service for data communication that can be provided in a mobile communication system. The mobile communication system has made many technical developments to provide such a high speed multimedia service. As a result, the standardization work for 1x EV-DO system and 1x EV-DV system is completed in 3GPP2, a synchronous standard. Reached. Many countries have now reached the point of providing service for 1x EV-DO systems.

Among the mobile communication systems, the 1x EV-DO system is a system that processes only high-speed data and cannot basically provide a voice service. This is because high speed data is provided in a packet form. Therefore, there is a demand for a method capable of providing a voice service using a packet form in not only the 1x EV-DO scheme but also other systems that provide high-speed data services. In order to provide a voice service in a mobile communication system that can provide a packet data service in response to such a demand, a technology for providing a voice service to users using packet data such as a VoIP service or a PTT service is provided. This is evolving.

Currently, the PTT service is provided using the 1: N communication method, and the 1: 1 communication method generally uses the VoIP form. However, PTT service may also provide 1: 1 service. Such a PTT service generally performs communication between users in a specific group. When a user acquires a voice and transmits a voice message, the other users unilaterally receive a voice message of the user who has obtained the voice. (half-duplex) is adopted.

However, the PTT service is also the same as the voice service, but because it communicates with several users, some specific users may not receive a voice message that is unilaterally delivered. For example, users existing in the group may not be able to listen to a message that is unilaterally delivered to a user, such as a user who is turned off or is not waiting for reception. In addition, the user who has obtained the right to speak does not know whether the message is correctly delivered without checking with each user. If the message to be delivered is very urgent or important, even though there are users who do not listen to the message, communication may be unilaterally, which may cause a problem that the reliability of the PTT service is degraded.

Accordingly, an object of the present invention is to provide a PTT system and a method of operating the same, which allow reliable data transmission when a caller transmits a message by a destination group or an individual.

It is another object of the present invention to provide a reliable PTT system and a method of operating the same, which can be received by both a called group or an individual when a caller transmits an urgent message.

The PTT system of the present invention for achieving the above object performs an access network (AN) for accessing a PoC client and a PTT service and performs session establishment processing upon initial registration and call establishment request of the PoC client. A Group and List Management Server that stores and manages a Session Initiation Protocol (SIP) / IP (Internet Protocol) core and a list of individuals and groups for the PoC client and transmits the list to a PoC server when needed; Presence server that stores and manages location information of PoC client and transmits it to PoC server if necessary, and PoC server and originating PTT subscriber that transmits and receives actual media between the PoC clients and temporarily buffers the media. Is required or one of the receiving PTT subscribers cannot receive data from the calling PTT subscriber. In this case, it is characterized by comprising a Dispatch-Multimedia Messaging Service (D-MMS) for storing the data separately.

The PoC server has a memory capable of buffering media received from the PTT subscriber.

The D-MMS transmits voice and message to the subscriber when the PTT subscriber stores the media.

PTT service providing method of the present invention for achieving the above object is a first step of transmitting a predetermined message to the PoC server for the call setup by the originating PoC client to a specific group and individual and the received message A second step of the PoC server confirming the destination PoC client to transmit the message to the PoC client and to receive an acknowledgment message; and when the PoC server receives a Decline message from the destination PoC client, the DC. A third process of transmitting / receiving a storage request and a response signal to an MMS unit, a fourth process of the D-MMS storing transmission data from the originating PoC client, and the D-MMS transmitting the stored data to a destination PoC client; And a fifth process of transmitting an alarm signal.

DETAILED DESCRIPTION Hereinafter, detailed descriptions of preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same components in the drawings represent the same numerals wherever possible. Specific details are set forth in the following description, which is provided to aid a more general understanding of the invention. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the following description, after providing a PTT system for providing a multimedia messaging service (MMS) according to the present invention, embodiments of the service that can be provided in the system will be described. Here, the MMS is an extended service form of a short messaging service (SMS), and refers to a service capable of attaching a large amount of multimedia data such as pictures, videos, background music, and voice as well as texts.

1 is a block diagram showing the configuration of a PTT system 100 according to the present invention.

Referring to FIG. 1, a push to talk over cellular (PoC) client 101 is a terminal capable of using a PTT service as well as a general mobile communication system, and the PcC client 101 is connected through an access network 103. Done. The access network 103 may be a CDMA / WCDMA-based cellular system, a wireless LAN, a mobile communication network such as HPi.

The SIP / IP core 105 performs subscriber registration and authentication. In addition, when the SIP / IP core 105 requests a connection request from the PoC client 101, the SIP / IP core 105 finds an appropriate PoC server 111. Accordingly, when performing SIP signaling such as registration procedure or call setup processing of the PoC client 101, the signaling processing signal always passes through the SIP / IP core 105 through a signaling path L1.

GLMS (Group and List Management Server) 107 is a server for storing and managing a database for the PTT service to manage the PoC specific group. That is, the GLMS provides an instant group talk function with other PTT service subscribers or groups. Accordingly, the GLMS manages a plurality of lists, and the list includes contact lists, group lists, and access lists. The contact list represents an address book for providing the instant group call function, and the group list represents a PoC specific group. Lastly, the access list is a list representing a rule on whether or not to allow a specific user to receive a PTT call. The access list is divided into an allow list and an reject list.

Presence Server (109) is a network element that manages the presence (Presence) information of the subscriber to provide the PTT service to collect, store, and Presence information for the PoC client 101, It serves to distribute. In this case, the presence information is information to know whether the subscriber is connected, etc. The PoC client informs the presence server of its own presence information when the periodic or state changes, and the presence server stores the information. Presence information of the PoC client is informed by the request of the server 111 or another PoC client. The presence server may manage the group's presence information in association with GLMS.

Next, the PoC server 111 and the dispatch multimedia messaging service unit (D-MMS) 113 are provided in the present invention, and the PoC server 111 is connected to the PoC client 101. The bearer path L2 that can transmit and receive the actual media is set. Here, the media refers to a large amount of multimedia such as audio and video data. Thereafter, the PoC service subscriber receives the address of the PoC service subscriber from the GLMS 107 and transmits the media to the called party's person or group existing in the external PoC network 115. In addition, the PoC server 111 has a predetermined memory in itself, and when the caller receives a signal indicating that the caller is an emergency or important message, the PoC server 111 temporarily stores the media transmitted by the caller. If the PoC server 111 receives a Decline message to the called party who has not received the data while transmitting the caller's data, the pre-stored data is stored in the D-MMS unit. 113 can be stored immediately.

The D-MMS unit 113 may be connected to the PoC server 111 and the external PoC network 115 to store a large amount of multimedia data capable of providing an MMS service. When the caller makes a 1: 1 communication or communication with a specific group, the caller may store data necessary for the D-MMS unit 113 when some specific subscribers cannot receive the call. Then, the D-MMS unit 113 notifies the called party that has not received the sender's data of the future by transmitting an alarm signal (Alert) to inform that there is unreceived data. The called party receiving the alarm signal may receive the caller's data by connecting to the D-MMS unit 113. In this case, the content included in the alarm signal may be a brief content of the caller's information and data, or may further include an emergency notification message. A detailed description thereof will be provided in the embodiments to be described later.

Next, a process of a service that can be provided using the PTT system 100 of the present invention will be described according to embodiments.

FIG. 2 is a diagram illustrating a signal flow for a case in which a called party is out of service in a PTT direct call according to the first embodiment of the present invention, and shows a case in which the called party is in a shaded area or turned off. Note that reference numerals 401, 403, 405, and 407 in FIGS. 2 to 5 to be described below have the same structure as those of 101, 105, 111, and 113 of FIG. 1, respectively, but use different reference numerals for convenience of description. Should be.

Referring to FIG. 2, the originating PoC client A 401 requests a direct call setup from the receiving PoC client B 411. The call establishment generally uses SIP signaling or the like. The protocol will be used. In the case of the SIP signaling, all signals always pass through the SIP / IP core through the SIP / IP core.

Referring to the signal processing according to the embodiment of the present invention, the originating PoC client A 401 first transmits an invitation request message (INVITE) to the receiving PoC client B 413 to establish a SIP / IP core in step 420. To A 203. In this case, the INVITE message includes an address list of a calling party and a receiving party, a type of calling medium, a service type, and protocol information necessary for obtaining a voice. In this case, the protocol required for obtaining the right to speak mainly uses a real-time control protocol (RTCP).

Upon receiving the INVITE message, the SIP / IP Core A 403 transmits the INVITE message to the PoC server A 405 in step 221. Thereafter, the PoC server A 405 checks the contents of the INVITE message to confirm the destination of the message, and then transmits the INVITE message to the SIP / IP core A 403 again in step 422. In step 423, the SIP / IP Core A 203 finds the SIP / IP Core B 209 of the network including the receiving PoC Client B 211 and transmits the INVITE message.

The receiving SIP / IP core B 411 receiving the INVITE message transmits the INVITE message to the PoC server B 409 of the corresponding network in step 424. Upon receiving the INVITE message, the PoC server B 409 checks the INVITE message in step 425 and transmits the INVITE message to the SIP / IP core B 209. In step 426, the SIP / IP Core B 411 checks the INVITE message, finds a receiving Poc client B 413, and transmits the INVITE message. The SIP / IP Core B 411 then waits to receive a RING signal, which is a response message. However, in this case, since the PoC client B 413 is in a shadowed area or powered off, the RING signal cannot be transmitted. Then, the SIP / IP Core B 411 retransmits the INVITE message for an unknown number of times. If the RING signal is not received thereafter, the SIP / IP Core B 411 determines in step 428 that the PoC Client B 413 The service failure message is transmitted to the PoC server B 409 by determining that the reception is impossible. Upon receiving the service failure message, the PoC server B 409 determines that the PoC client B 413 is out of service in steps 429 to 430.

A Global Failure message, such as a 603 Decline message, is sent to the originating PoC server A 405 to inform. At this time, if the PoC client A 401 includes the information indicating that the INVITE message is urgent or important data in advance, the PoC server A 405 attempts to connect to the D-MMS unit 407 in step 432. Send a service request (Servic Req) message. At this time, the protocol used may be SIP using INVITE, OK message, or similar protocol.

Upon receiving the service request message, the D-MMS unit 407 transmits a service response message to the PoC server A 405 in step 433, and the PoC server A 405 in steps 434 to 435. An OK message is transmitted to the PoC client A 401 for bearer connection with the PoC client A 401. At this time, in step 436, the D-MMS unit 407 notifies the PoC client B 413 using a voice or a message so that the originating PoC client B 413 knows.

Then, the PoC client A 401 stores the media including voice or necessary message in the D-MMS unit 407 through the PoC server A 405 in steps 437 and 438. When the D-MMS unit 407 stores the media transmitted by the PoC client A 401 in step 439, the D-MMS unit 407 sends an alarm signal to the PoC client B 413 using a notification method using a text message. Will be sent. In this case, the alarm signal may include calling information (caller ID, group ID, calling time, etc.) and information indicating that it is important data.

The second embodiment of the present invention is a case in which the called party has previously set the call rejection function. In this embodiment, as shown in Figure 3 as a process of being connected directly to the D-MMS unit 407 without a call setup request from the calling party.

Referring to FIG. 3, first, the receiving PoC client B 413 sets up the incoming call rejection in advance to the PoC server B 413 in step 500 through a registration process before call setting is made if necessary. do. Then, the originating PoC client A (401) receives the receiving side PoC through SIP / IP cores A and B (403, 409) from step 520 to step 524 to make a call setup request to the receiving side PoC client B (413). The server B 409 transmits an INVITE message. In the PoC server B 409, since the PoC client B 413 sets the call rejection in steps 525 to 527, the PoC server B 413 services the PoC server A 405 through a Global Failure message. It will tell you it's impossible. At this time, if the PoC server A 405 includes information indicating that it is urgent or important data in the INVITE message as in the first embodiment, the PoC server A 405 services the D-MMS unit 407 in step 528. The request message is transmitted, and in step 529, the service response message is received. Since step 530 to step 535 are the same as step 434 to step 439 of FIG. 4 will be omitted.

The third embodiment of the present invention is a case in which a called party rejects a call when a call establishment request is received or a case in which a called terminal is busy.

4 is a signal flow diagram illustrating a signal processing procedure according to a third embodiment of the present invention. Referring to FIG. 4, first steps 620 to 626 are omitted because the same steps 420 to 426 of FIG. 2 are the same. In the present embodiment, unlike the first embodiment, since the connection is possible, the destination PoC client B 413 transmits a RING signal, which is a response message, to the SIP / IP core B 411 in step 627. Then, if the process proceeds to step 633, the RING signal is transmitted to the PoC client A (401).

In step 633, the PoC client B 413 rings the phone. According to an exemplary embodiment of the present invention, when the user of the PoC client B 413 rejects a hand signal, rejects a hand signal, or calls, the user of the PoC client B 413 according to an embodiment of the present invention. Deny the response by pressing a predetermined button provided in the terminal of. Then, the PoC client B 413 transmits the global failure message, which is a rejection message, to the PoC server A 405 via the SIP / IP cores A and B 405 and 411 in steps 635 and 639. ) Will tell you that it is out of service. Since step 640 to step 647 is the same as step 434 to step 439 of FIG. 2 will be omitted.

The fourth embodiment of the present invention is a case in which the caller wants to connect directly to the called party's D-MMS.

5 is a signal flow diagram illustrating a signal processing process according to a fourth embodiment of the present invention. Referring to FIG. 5, first, a user of the originating PoC client A 401 presses a predetermined button on his terminal or selects a specific number to directly connect to the D-MMS unit 407 as in step 720. You will connect and try it yourself. In operation 721, the PoC client A 401 transmits an INVITE message for directly connecting to the D-MMS unit 407 to the SIP / IP core A 403. Upon receiving the INVITE message, the SIP / IP Core A 403 transmits to the originating PoC server A 405 in step 722. Then, the PoC server A 4055 transmits and receives a service request message and a service response message in steps 723 and 724. When the PoC server A 405 confirming the service response message transmits an OK signal in steps 725 and 726, the D-MMS unit 407 sends a voice and a message for announcement broadcast in step 727 to the PoC client A 401. ). In operation 728 and 729, the PoC client A 401 stores the media including voice or necessary data in the D-MMS unit 407 through the PoC server A 405. When the D-MMS unit 407 stores the media transmitted by the PoC client A 401 in step 439, the alarm signal shown in FIG. 2 is transmitted to the PoC client B 413 by an SMS notification method. ) Will be sent.

In the above-described embodiments, all of the processes shown in the PTT direct call are shown. In the following description, a PTT group call will be described. In the PTT group call, the same process as the PTT direct call will be omitted since it is only different in a 1: 1 relationship.

A fifth embodiment of the present invention is a case where a specific subscriber is turned off or in a shaded area in a PTT group call.

6 is a signal flow diagram illustrating a signal processing procedure according to a fifth embodiment of the present invention. In the present embodiment, in the case of a PTT group call, there are a large number of called parties. However, in the following description, for convenience of explanation, the called party is described as two PoC clients B and C (413, 813) in one group. That is, in the above embodiment, the PoC client C 813 is added.

Referring to FIG. 6, the originating PoC client A 401 first sends an INVITE message to make a call establishment request to the PoC clients B and C 413 and 813 included in the preset group in steps 820 to 822. To the PoC server A 403. After receiving the INVITE message, the PoC server A 403 confirms the group and the destination from the INVITE message in steps 823A and 823B, and then transmits the INVITE message to the PoC clients B and C 413 and 813, respectively. In the present embodiment, it is assumed that the PoC client B 413 is a terminal capable of a normal call and the PoC client C 813 has previously set up a call rejection. Therefore, since the PoC client B 413 receiving the INVITE message in step 823A is a general call procedure shown in the Open Mobile Alliance (OMA) standard until step 845, it will be omitted here.

On the other hand, since the PoC client C 813 has set the call rejection state in advance, the receiving PoC server C 809 receiving the INVITE message transmitted from the PoC server A 405 rejects in step 826B (Decline). A Global Failure message is sent to SIP / IP Core C (811). Then, the SIP / IP core C 811 transmits the PoC server A 403 to the PoC server A 403 by proceeding to steps 846 and 847 to inform that the PoC client C is in a call rejection state.

Meanwhile, when the PoC server A 405 receives the rejection message from the PcC client C 813, the PoC server A 405 stores the reject message in the D-MMS unit 407. However, since the PoC client A 813 cannot transmit again when the rejection message is late, the PoC server A 405 should have a predetermined memory to buffer the media.

That is, if the client A 401 transmits the service request and response message in steps 848 and 849 while transmitting the media to the client B 413, the PoC server A 405 stores the media in advance in step 850. It is copied to and stored in the D-MMS unit 407. After that, the D-MMS unit 407 stores the media so that the PoC client C 413 knows whether there is any unreceived media in step 851. The PoC client C 813 may be displayed on the display unit of the PoC client C 813 by using a voice.

In the present embodiment, the PoC client C 813 has set the call rejection state, but the caller may intentionally reject the call when the terminal is powered off and cannot answer or is busy. . In this case, since only the relationship of 1: 1 differs from the first embodiment and the third embodiment of the present invention, the actual signal processing is the same, and thus description thereof will be omitted.

A sixth embodiment of the present invention is a case in which a caller directly connects to a D-MMS part of a group in a PTT group call.

7 is a signal flow diagram illustrating a signal processing procedure according to a sixth embodiment of the present invention. In the present embodiment, in the case of group communication in 1: 1 communication in the fourth embodiment, the actual signal processing is performed almost the same.

Referring to FIG. 9, first, a user of the originating PoC client A 401 presses a predetermined button on his terminal or makes a specific number to make a direct connection to the D-MMS unit 407 as in step 920. You will connect and try it yourself. In step 921, the PoC client A 401 transmits an INVITE message for directly connecting to the D-MMS unit 407 to the SIP / IP core A 403. Upon receiving the INVITE message, the SIP / IP Core A 403 transmits to the originating PoC server A 405 in step 922. The PoC server A 4055 then transmits and receives a service request message and a service response message in steps 923 and 924. When the PoC server A 405 confirming the service response message transmits an OK signal in steps 725 and 726, the D-MMS unit 407 sends a guide message using voice or text in step 927 to the PoC client A 401. ). In operation 928 and 929, the PoC client A 401 stores the media including the voice or necessary message in the D-MMS unit 407 through the PoC server A 405.

The process is almost the same as in the fourth embodiment. However, in the present embodiment, the D-MMS unit 407 does not store the media for each called party but separately stores them in a group memory. Then, as shown in steps 930 and 931 of the D-MMS unit 407, the PoC client B and C 413 and 813 refer to the address of the called party included in the group from the PoC server A 407. The alarm signal (Alert) shown in FIG. 2 is transmitted by a notification method such as a message. In such an embodiment, the group D-MMS function may be used as a group voice bulletin board.

As described above, in the embodiment of the present invention, the multimedia service is provided with a D-MMS unit, but a service such as a short message service (SMS) for providing a text service or a voice mail service (VMS) for storing a voice message may also be provided. Can be.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, since the present invention includes a D-MMS unit in the conventional PTT service, when a caller leaves urgent or important data, a receiver who does not receive the data may later receive it, thereby providing a more reliable service. Next, in the present invention, a service provider or a user who receives a PTT service also has many effects.

1. User position

1) When the user is in a situation where the incoming call is impossible, not only can the user hear the contents stored in the D-MMS at a desired time, but also repeat the mood.

2) You can connect to D-MMS by simply pressing a certain button in a situation where call is difficult.

3) If a specific receiver fails to participate in the group call, the call history is stored in the D-MMS, so the caller does not have to repeat the same information later.

4) In a group call where a celebrity fan club management or advertisement can be used, a group D-MMS can be stored in a group call so that many group subscribers can connect and listen when desired.

2. Business position

1) Even if it is impossible to establish a PTT call between the caller and the called party, the caller may be connected to the D-MMS and the caller may be connected for repeated listening.

2) In case of extending to group D-MMS, various services are available when used as group voice bulletin board.

Claims (9)

Multiple SIP / Push to Talk Over Cellular (PoC) clients that can use the PTT service and the PoC client operate to perform Session Initiation Protocol (SIP) / IP (Internet Protocol) signaling during initial registration and call setup. In the Push to Talk (PTT) system comprising an IP core, An access network (AN) accessing the PoC client to provide a PTT service; A Session Initiation Protocol (SIP) / IP (Internet Protocol) core that performs session establishment processing upon initial registration and call establishment request of the PoC client; A group list management server for storing and managing a list of individuals and groups for the PoC client and transmitting the list to a PoC server when necessary; Presence server that stores and manages location information of PoC client and transmits to PoC server if necessary, A PoC server that transmits and receives actual media between the PoC clients and temporarily buffers the media; When a calling party PTT subscriber is required or when a specific receiver among the receiving PTT subscribers does not receive the data of the calling PTT subscriber, it is configured with a Dispatch-Multimedia Messaging Service (D-MMS) storing the data separately. The system described above. The method of claim 1, wherein the PoC server, And a memory capable of buffering media received from the PTT subscriber. The method of claim 1, wherein the D-MMS, The system transmits voice and messages to the subscriber when the PTT subscriber stores the media. Push-to-talk configured with a plurality of Push to Talk Over Cellular (PoC) clients that can use the PTT service and a Dispatch Multimedia Messaging Service (D-MMS) that stores data of the PoC client. In a method of providing a multimedia messaging service in a (Push to Talk: PTT) system, A first step of the originating PoC client transmitting a predetermined message to a PoC server for call setup to a specific group and individual; Receiving, by the PoC server, the receiving PoC client, transmitting the message to the PoC client, and receiving an acknowledgment message; A third step of transmitting / receiving a storage request and response signal to the D-MMS unit when the PoC server receives a Decline message from the called party PoC client; A fourth step of storing, by the D-MMS, transmission data from the originating PoC client; And the fifth step of the D-MMS transmitting the stored signal to the destination PoC client. The method of claim 4, wherein And the PoC client receiving the alarm signal checks the stored data by accessing the D-MMS. The method of claim 4, wherein The method as claimed in claim 1, wherein the predetermined message includes information indicating that the message is urgent or important data. The method of claim 4, wherein And transmitting, by the D-MMS unit, a transmission and reception signal to the originating PoC client using a voice or a message after transmitting and receiving the storage request and response signal in the third process. Push-to-talk configured with a plurality of PoC (Push to Talk Over Cellular) clients that can use the PTT service and a Dispatch-Multimedia Messaging Service (D-MMS) to store data of the PoC client. In a method of providing a multimedia messaging service in a (Push to Talk: PTT) system, When the calling PoC client directly stores the specific group and individual in the D-MMS, the PoC client transmits and receives a storage request and response signal directly to the D-MMS using the PoC server; Storing, by the D-MMS, transmission data from the originating PoC client; And transmitting, by the D-MMS, an alarm signal to the destination PoC client of the stored data. The method of claim 8, And the PoC client receiving the alarm signal checks the stored data by accessing the D-MMS.

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