KR20090002274A - Portable terminal and method for communicating using push to talk protocol thereof - Google Patents

Abstract

A portable terminal and a PTT(Push To Talk) communications method for easily progressing point-to-point communications of a specific portable terminal during PTT group communication are provided to perform point-to-point communications in a PTT group communication mode. A key input unit(105) comprises a PTT button(107). A controller(111) acquires a symbol within a group member on PTT group communications in a PTT group communications mode. A PTT module(113) selects a specific symbol between the given symbol and the specific symbol. The portable terminal corresponding to the selected symbol performs communication. The controller assigns number to the group member in the PTT group communications mode. The controller assigns a number to the group member. The PTT module performs point-to-point communications with the portable terminal corresponding to the inputted number.

Description

PORTABLE TERMINAL AND METHOD FOR COMMUNICATING USING PUSH TO TALK PROTOCOL THEREOF

1 is a diagram schematically illustrating a communication relationship between a mobile terminal and a push-to-talk server for push-to-talk communication according to the present invention.

2 is a block diagram schematically illustrating a portable terminal for push-to-talk communication according to the present invention.

3 is a flowchart schematically illustrating a push-to-talk communication method of a mobile terminal according to the present invention.

4A is a diagram illustrating a screen to which a number is assigned to a group member during push-to-talk group communication of a mobile terminal according to the present invention.

4B is a diagram illustrating a screen for performing one-to-one communication with a specific mobile terminal during push-to-talk group communication of the mobile terminal according to the present invention.

The present invention relates to a mobile terminal and a push-to-talk communication method thereof, and in particular, a mobile terminal capable of easily performing one-to-one communication with a user of a specific mobile terminal during PTT group communication. And a PTT communication method thereof.

In general, a mobile communication system of a mobile terminal divides an entire service area into a plurality of base station (BS) areas to configure cells, which are small service areas. The base stations are centrally controlled by a mobile switching center (MSC) to allow subscribers to make calls while moving between cells.

As a mobile communication technology is developed, various technologies for combining an IP (Internet Protocol) network and a mobile communication network using an Internet-based protocol have been developed. One such technology is called VoIP (Voice over IP), a packet-based voice service using IP.

This packet-based call service has a disadvantage in that a call setup time is relatively long because a call must be established through a mobile communication network and an IP network. In order to solve this disadvantage, it is possible to provide an interactive call service such as a group call and a private call by using the multi-cast function of the IP network. In this case, the interactive call service is a kind of call in which calls are made by users' interactions, for example, a PTT function as in a walkie-talkie. The group call refers to a multi-party call between users in a predetermined group of users, and the personal call refers to a one-to-one call between users in a predetermined group of users.

In the PTT communication, a user selects a group or a group of colleagues or friends displayed on the mobile terminal or a user who wants to make a voice call and then presses the PTT button while the user is logged in. Thereafter, after establishing a one-to-one or group communication path in a network providing PTT communication, it is possible to communicate with each other through the established communication path.

In this PTT group communication, a story of a person who obtains a voice is transmitted to users of the remaining mobile terminals in the group. Therefore, when one-to-one communication with a specific user belonging to a group is released, the PTT group communication needs to be released and then PTT communication with the specific user must be re-initiated.

Accordingly, an object of the present invention is to provide a mobile terminal and a PTT communication method thereof capable of performing one-to-one communication with a user of a specific mobile terminal while maintaining group communication between the remaining mobile terminals in the PTT group communication mode. .

Another object of the present invention is to assign a number to a group member in the PTT group communication mode in the PTT group communication mode, by selecting a specific number, a portable terminal capable of one-to-one communication with the user of the mobile terminal corresponding to the selected number; It is to provide a PTT communication method thereof.

The present invention for achieving the above object is a PTT communication method of a mobile terminal, in the PTT group communication mode, displaying a symbol on a member of the group in the PTT group communication, and selecting a specific symbol from the displayed symbol And performing one-to-one communication with the mobile terminal corresponding to the selected symbol.

According to another aspect of the present invention, there is provided a portable terminal, comprising: a key input unit including a PTT button, a control unit for giving a symbol to a group member communicating with the PTT group in a PTT group communication mode, and It includes a PTT module for selecting a specific symbol, and performs one-to-one communication with the mobile terminal corresponding to the selected symbol.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Before the detailed description of the present invention, the portable terminal will be described by way of example and for convenience of description, but the present invention is not limited thereto. That is, the portable terminal according to the embodiments of the present invention provides a convenience to the user and enables PTT communication. Preferably, the portable terminal is a mobile terminal, a mobile phone, a portable multimedia player (PMP), an individual. Applicable to all information communication devices and multimedia devices such as personal digital assistants (PDAs), smart phones, notebooks and personal computers, and applications thereof. will be.

Example

1 is a diagram schematically illustrating a communication relationship between a portable terminal for PTT communication and a PTT server according to the present invention.

Referring to Figure 1, the configuration of a system for PTT communication according to the present invention comprises a plurality of mobile terminals (100a, 100b, 100c), base stations (BS; Base Station, 130a, 130b), mobile switching center (MSC; Mobile) Switching Center, and 150 and the PTT server 170 is configured.

The mobile terminal 100 may use a voice call, a short message service (SMS), a multimedia message service (MMS), a built-in camera, and shoot a subject according to a user's request. Built-in MP3 player can play music according to user's needs.

In addition, the portable terminal 100 includes a PTT button according to the present embodiment, and PTT communication is possible according to the input of the PTT button. The mobile terminal 100 includes a PTT module that performs a PTT related operation including a PTT communication request to the PTT server 170. In addition, when the PTT communication is performed, the mobile terminal 100 wirelessly transmits a PTT communication request of an appropriately set format to the base station 130. In addition, the mobile terminal 100 may access the PTT server 130 and perform modifications such as creating, changing, and deleting group list information and personal information set by the user of the mobile terminal 100.

The base station 130 is connected to the switching center system 150, and the switching center system 150 is connected to the PTT server 170 through the data network. The switching center system 150 provides the PTT server 170 with the PTT communication request from the mobile terminal 100 through the base station 130, and the switching center system 150 includes the PTT communication request. And an IWF (Inter Working Function) for processing data packets.

The PTT server 170 performs a real time management operation of the PTT user group. That is, the PTT server 170 not only controls overall PTT user group, but also re-enters, maintains, and distributes a registration list for each user, call setup and separation of necessary systems and network resources, as well as PTT communication requests. The PTT server 170 may allow a right to speak to any one of the portable terminals 100 currently connected.

The PTT server 170 includes a PTT Over Cellular (POC) server 171 and a Group and List Management Server (GLMS) 173. The POC server 171 performs a communication function for a PTT service in a mobile communication network, and the GLMS 173 manages information of a PTT user and a group list of each user.

Hereinafter, a portable terminal for PTT communication according to the present embodiment will be described. 2 is a block diagram schematically illustrating a portable terminal for PTT communication according to the present invention.

Referring to FIG. 2, the portable terminal 100 according to the present invention has a configuration of an RF unit 101, a display unit 103, a key input unit 105, a memory unit 109, and a control unit 111.

The RF unit 101 performs a wireless communication function of the mobile terminal 100. The RF unit 101 includes an RF transmitter for upconverting and amplifying a frequency of a transmitted signal, and an RF receiver for low noise amplifying and downconverting a received signal.

The RF unit 101 starts an operation in response to a user's manipulation signal input through the PTT button 107 and performs PTT data processing for providing a PTT service. For example, when the PTT button 107 is input, the RF unit 101 waits for the reception of the PTT data and transmits the voice of the user input through the microphone.

The display unit 103 visually displays various information related to the state and operation of the portable terminal 100. The display unit 103 may use an LCD, in which case the display unit 103 includes an LCD control unit, an LCD display element, and the like. When the LCD is implemented using a touch screen method, the display unit 103 may operate as an input unit.

When the display unit 103 displays the group member in PTT group communication in the PTT group communication mode according to the present embodiment, a symbol, for example, a number, is assigned to the group member and displayed together. The display unit 103 distinguishes and displays a user of a portable terminal having a voice in the PTT group communication mode. For example, the user of the mobile terminal is displayed using a bar having a different color (see FIG. 4A). When one-to-one communication with a user of a specific mobile terminal is performed during the PTT group communication, the display unit 103 distinguishes and displays the mobile terminal, which has one-to-one communication, from other mobile terminals. For example, the user of the mobile terminal uses bars of different colors and displays text as one-to-one communication (see FIG. 4B).

The key input unit 105 receives a user's operation signal for controlling the operation of the portable terminal 100. The key input section 105 has a PTT button 107 according to the present embodiment. The PTT button 107 transmits a user's operation signal for using the PTT service to the control unit 111. To this end, the PTT button 107 is a dedicated key and may be provided separately in the portable terminal 100. Alternatively, the PTT button 107 may be one of the keys included in the key input unit 105.

The key input unit 105 performs an operation such as a PTT connection request, group selection for PTT group communication, key input for one-to-one communication among PTT group communication, and end of one-to-one communication. Here, the key input unit 105 manipulated for one-to-one communication during PTT group communication may be a number key assigned to a group member or a navigation key.

The memory unit 109 stores programs and information necessary for the operation of the portable terminal 100. The memory unit 109 may store a group list and members of the group list for PTT communication according to the present embodiment. Such group lists and members may be received via the PTT server 170.

The controller 111 controls the overall operation of each component of the mobile terminal 100. The controller 111 controls the PTT communication function of the mobile terminal 100 according to the present embodiment. The control unit 111 includes a PTT module 113. When the PTT button 107 is input, the control unit 111 requests the PTT connection to the PTT server 170 by driving the PTT module 113.

When the PTT module 113 receives a response to the PTT connection request, the PTT module 113 receives the set group list together, and the control unit 111 displays this on the display unit 103. When the controller 111 determines that the group for PTT group communication is selected through the key input unit 105, the controller 111 requests the PTT group communication to the PTT server 170 by driving the PTT module 113.

When the PTT group communication is performed, the controller 111 assigns a symbol to the group member in the PTT group communication. Here, the symbol may be a number. The controller 111 may allocate the numbers in order according to the frequency of transmission and reception of the communication event. The transmission / reception frequency of a communication event refers to a transmission / reception frequency in a communication event including all voice calls, text message transmissions, and voice calls in PTT communication. Alternatively, the control unit 111 may assign numbers in the order of the name of the group member or the number order of the portable terminal.

In addition, when a key for one-to-one communication, for example, a specific number key is input, the PTT module 113 requests one-to-one communication with the mobile terminal corresponding to the input number to the PTT server 170 to perform one-to-one communication. When performing the one-to-one communication, the PTT module 113 requests the PTT server 170 to maintain existing PTT group communication for mobile terminals that do not perform one-to-one communication in the PTT group. When the PTT module 113 ends one-to-one communication with a specific mobile terminal, the PTT module 113 returns to the existing PTT group communication and performs PTT group communication again.

As described above, the controller 111 and the PTT module 113 have been described as performing functions related to the PTT service, but are not limited thereto. That is, the controller 111 may include the PTT module 113 or the PTT module 113 may be provided in the portable terminal 100 separately from the controller 111 to perform functions related to the PTT service as described above. .

Hereinafter, the PTT communication method of the portable terminal according to the present embodiment will be described. 3 is a flowchart schematically illustrating a PTT communication method of a mobile terminal according to the present invention. 4A illustrates a screen in which a number is assigned to a group member during PTT group communication of the mobile terminal according to the present invention, and FIG. 4B performs one-to-one communication with a specific mobile terminal during PTT group communication of the mobile terminal according to the present invention. It is a figure which shows the screen to make.

1 to 3, referring to the PTT communication method of the mobile terminal according to the present embodiment, first, as shown in FIG. 3, the control unit 111 of the calling mobile terminal 100a uses the PTT button 107. Check whether the input (S301). The user of the calling mobile terminal 100a may input the PTT button 107 for PTT group communication or PTT one-to-one communication.

When the PTT button 107 is confirmed, the control unit 111 of the calling mobile terminal 100a drives the PTT module 113 to request a PTT connection to the PTT server 170 (S303).

Subsequently, the PTT server 170 checks the user of the mobile terminal 100a through the GLMS 173 and responds to the PTT connection request of the user of the mobile terminal 100a. In operation S305, the group list which is the PTT communication group subscriber information of the user of the mobile terminal 100a is transmitted.

Next, the control unit 111 of the calling mobile terminal 100a displays the group list received from the PTT server 170 on the display unit 103 (S307). Here, as described above, the group list set by the calling mobile terminal 100a user is not limited to being received from the PTT server 170 at the time of PTT connection. For example, during PTT connection, the control unit 111 may display the group list stored in the memory unit 109 on the display unit 103.

Thereafter, the control unit 111 of the calling mobile terminal 100a receives a group for PTT group communication (S309). The user selects a group for PTT group communication from the group list displayed in step S307 described above.

Subsequently, the control unit 111 of the calling mobile terminal 100a transmits the PTT group communication request message INVITE to the receiving mobile terminals 100b and 100c of the selected group (S311). The PTT communication request message includes information on IDs of the calling mobile terminal 100a and the receiving mobile terminals 100b and 100c.

In detail, the process 111 of the calling mobile terminal 100a drives the PTT module 113 to connect the PTT communication request message with the corresponding mobile terminal 100a in the form of a short data burst (SDB). The base station 130 is transmitted. Thereafter, a service option (SO_PTT) negotiation is performed with the corresponding base station 130 for the PTT service, and a traffic channel (TCH) setup is performed. Here, the Nego is a process of preparing a higher network session from the physical layer including the PPP session to the application layer.

Upon receiving the PTT group communication request message, the PTT server 170 checks the ID of the calling mobile terminal 100a in the PTT communication request message and transmits it to the first receiving mobile terminal 100b (S313). The PTT server 170 transmits a PTT communication request message to the base station 130 which is being serviced by the first receiving-side portable terminal 100b. Here, the base station 130 periodically transmits a paging signal (General Page) to the first receiving-side portable terminal 100b, and the first receiving-side portable terminal 100b responds to a paging signal (Page Response). Is transmitted to the base station 130. During this paging, the base station 130 transmits a PTT communication request message in the form of SDB to the first receiving-side portable terminal 100b.

Next, when the control unit 111 of the first receiving side mobile terminal 100b accepts the PTT group communication, the PTT module 113 of the first receiving side mobile terminal 100b sends a message indicating that the PTT group communication request is accepted. It transmits to the PTT server 170 (S315). Here, when the first receiving-side portable terminal 100b receives the PTT communication request message, the first receiving side portable terminal 100b displays this on the display unit 103. When the PTT group communication request message is transmitted to the first receiving side mobile terminal 100b, the control unit 111 of the first receiving side mobile terminal 100b receives the PTT group communication request message to the base station 130 normally. Notify transmits a signal.

In detail, when the PTT group communication request is accepted, the first receiving-side portable terminal 100b transmits the PTT group communication request acceptance message to the corresponding base station 130 in the SDB form. Thereafter, the first receiving-side mobile terminal 100b performs the traffic option setup for the PTT service in association with the corresponding base station 130 and performs traffic channel setup.

The PTT server 170 which has received the PTT group communication request acceptance message from the first receiving side mobile terminal 100b transmits it to the calling side portable terminal 100a (S317). The PTT server 170 transmits a PTT group communication request accept message through the base station 130 of the calling mobile terminal 100a.

Subsequently, as in steps S313 to S317 described above, the PTT server 170 transmits the PTT communication request message received from the calling mobile terminal 100a to the second receiving mobile terminal 100c (S319).

When the control unit 111 of the second receiving side mobile terminal 100c accepts the PTT group communication, the PTT module 113 of the second receiving side mobile terminal 100c sends a message indicating the acceptance of the PTT group communication request to the PTT server. Transmit to 170 (S321). The PTT server 170 which has received the PTT group communication request acceptance message from the second receiving side mobile terminal 100c transmits it to the calling side portable terminal 100a (S323). Here, in the present embodiment, the PTT group communication is performed with the two receiving side mobile terminals 100b and 100c as an example, but the present invention is not limited thereto, and the PTT group communication with the plurality of receiving side mobile terminals may be performed. have.

Next, PTT group communication is performed between the calling mobile terminal 100a and the receiving mobile terminals 100b and 100c (S325). Upon receiving the PTT communication request acceptance message, the control unit 111 of the calling mobile terminal 100a drives the PTT module 113 to complete the traffic channel setup. At this time, the control unit 111 of the calling mobile terminal 100a displays a message indicating that the PTT group communication request has been accepted from the receiving mobile terminals 100b and 100c on the display unit 103.

Subsequently, the control unit 111 of the calling mobile terminal 100a assigns a number to a member of the group in the PTT group communication, and displays it on the display unit 103 (S327). A screen in which numbers are assigned to members of a group in PTT group communication is shown in FIG. 4A. As shown in FIG. 4A, in the PTT group communication, the control unit 111 of the calling mobile terminal 100a assigns a number to a member of the group in the PTT group communication. In order to assign numbers, the control unit 111 sequentially assigns numbers according to the frequency of transmission and reception of communication events. The transmission and reception of a communication event may include both a voice call in a general wireless communication, a text message transmission and reception, a voice call in a PTT communication, and the like.

Here, the user (present) of the portable terminal 100d having the right to speak is displayed separately from the user of the other portable terminals 100b and 100c. For example, it is represented by bars of different colors. The mobile terminal 100e, which belongs to a group set by the user of the calling mobile terminal 100a but does not currently perform PTT group communication, is distinguished from the mobile terminals 100b, 100c, and 100d that are in PTT group communication. do. For example, it is represented by an icon of a different color. In the present embodiment, the group member is described as if the number assignment is made only in the calling party's mobile terminal 100a, but the present invention is not limited thereto. That is, in the PTT group communication in all the mobile terminals 100, a number may be assigned to the group member. In the PTT group communication, an example in which a number is assigned to a group member is described, but is not limited thereto. The control unit 111 may assign specific symbols to the group members and distinguish and display each member.

Next, the control unit 111 of the calling mobile terminal 100a recognizes that a specific number is selected (S329). The user may want one-to-one communication with a specific user (withdrawal) in the group during the PTT group communication through the above-described process. In this case, the user selects a number assigned to the user who wants one-to-one communication among the number of members displayed in the above-described step S327. As shown in FIG. 4B, the user may select the number key 2 assigned to the second receiving-side portable terminal 100c. This process is described as performing one-to-one communication by inputting a number key assigned to a group member, but is not limited thereto. The user may select a user of the mobile terminal for one-to-one communication using a navigation key and input a confirmation key to perform one-to-one communication with the user of the corresponding mobile terminal.

When a specific number key is input, the control unit 111 of the calling mobile terminal 100a requests the PTT server 170 for one-to-one communication with the selected second receiving mobile terminal 100c (S331). The one-to-one communication request message includes information on the IDs of the calling mobile terminal 100a and the second receiving mobile terminal 100c.

Upon receiving the one-to-one communication request message, the PTT server 170 checks the ID of the calling mobile terminal 100a in the one-to-one communication request message and transmits it to the second receiving mobile terminal 100c (S333).

When the control unit 111 of the second receiving side mobile terminal 100c accepts one-to-one communication, the PTT module 113 of the second receiving side portable terminal 100c sends a message indicating that the one-to-one communication request is accepted, the PTT server 170. It transmits to (S335).

The PTT server 170 receiving the one-to-one communication request acceptance message from the second receiving side mobile terminal 100c transmits it to the calling side portable terminal 100a (S337).

When receiving the one-to-one communication acceptance message from the PTT server 170 with the second receiving mobile terminal 100c, the control unit 111 of the calling mobile terminal 100a drives the PTT module 113 to transmit the PTT server 170. The mobile terminal 100b requests to maintain PTT group communication (S339). The PTT module 113 of the calling mobile terminal 100a performs a PTT such that other mobile terminals 100b except for the second receiving mobile terminal 100c to perform one-to-one communication continue to perform PTT group communication as before. Request this to the server 170.

The PTT server 170 receiving the PTT group communication maintenance request message of the other mobile terminals 100b transmits the PTT group communication to the mobile terminals 100b other than the second receiving terminal 100c that performs one-to-one communication. This is controlled to be maintained (S341).

Next, during the PTT group communication of the other mobile terminals 100b, the calling mobile terminal 100a and the second receiving mobile terminal 100c perform one-to-one communication (S343). The screen of the calling mobile terminal 100a is shown in FIG. 4B when one-to-one communication with the specific receiving mobile terminal 100c is performed during the PTT group communication of the other portable terminals 100b. As shown in FIG. 4B, during the PTT group call, the display unit 103 of the calling mobile terminal 100a indicates that one-to-one communication with the second receiving mobile terminal 100c is being performed. Here, the user (withdrawal) of the mobile terminal 100c in which one-to-one communication is being performed is displayed separately from the user of the other mobile terminals 100b, 100d, and 100e. For example, it displays bars of different colors and text indicating that it is a one-to-one communication.

Here, the display unit 103 of the calling mobile terminal 100a and the second receiving mobile terminal 100c in which one-to-one communication is performed is displayed with a screen as shown in FIG. 4B. However, in the display unit 103 of the other portable terminals 100b and 100d performing PTT group communication, the calling mobile terminal 100a and the second receiving mobile terminal 100c are rejected (DND; Do Not Disturb). It is displayed as.

On the other hand, although not shown in the figure, as described above, if the calling mobile terminal 100a and the second receiving mobile terminal 100c terminate while performing one-to-one communication, these mobile terminals 100a and 100c Return to the existing PTT group communication. That is, the controllers 111 of the calling mobile terminal 100a and the second receiving mobile terminal 100c terminate the PTT module 113 at the end of one-to-one communication with each of the mobile terminals 100a and 100c. The PTT server 170 requests the PTT group communication to the PTT server 170 and returns to the existing PTT group communication.

Meanwhile, the portable terminal and the PTT communication method thereof according to the present invention are not limited to the above-described embodiments and may be variously modified within the scope not departing from the technical spirit of the present invention. This will be readily apparent to those skilled in the art.

According to the present invention, since one-to-one communication with a specific person can be performed by inputting a number key while the PTT group communication is not interrupted during the PTT group communication, one-to-one communication can be easily performed during group communication and the security of the PTT group communication is maintained. Function can be enhanced. When the one-to-one communication is terminated, the PTT group communication can be easily performed again by returning to the existing PTT group communication, thereby improving user convenience.

Claims (18)

Displaying a symbol on a member of the group in the PTT group communication in a push to talk (PTT) group communication mode; And selecting a specific symbol among the displayed symbols and performing one-to-one communication with the portable terminal corresponding to the selected symbol. The method of claim 1, wherein the displaying process comprises: And assigning a number to a member of the group in communication with the PTT group and displaying the number. The method of claim 2, wherein the displaying process comprises: And a number is assigned to a member of the group in the PTT group communication in order of frequency of transmission and reception of a communication event. The method of claim 2, wherein the one-to-one communication is performed. And a specific number of numbers assigned to the members of the group, and one-to-one communication with the mobile terminal corresponding to the input number. The method of claim 2, wherein the one-to-one communication is performed. PTT communication method of the mobile terminal, characterized in that the portable terminals other than the portable terminal performing the one-to-one communication perform the PTT group communication. The method of claim 5, wherein performing one-to-one communication, Requesting one-to-one communication with the mobile terminal corresponding to the selected number to the PTT server; Performing one-to-one communication with the mobile terminal corresponding to the selected number upon receiving a one-to-one communication request acceptance message of the mobile terminal corresponding to the selected number from the PTT server; And requesting to maintain the PTT group communication of the mobile terminals other than the mobile terminal performing the one-to-one communication with the PTT server. According to claim 1, And returning to the PTT group communication after the one-to-one communication is terminated. The method of claim 1, wherein performing one-to-one communication, The PTT communication method of the mobile terminal, characterized in that the mobile terminal in the one-to-one communication is displayed in the rejected state to the mobile terminal in the PTT group communication. The method of claim 1, wherein performing one-to-one communication, And displaying the portable terminal in the one-to-one communication with the other portable terminals of the group member. A key input unit including a PTT button, A controller for giving a symbol to a group member in the PTT group communication in the PTT group communication mode; And a PTT module that selects a specific symbol from the given symbols and performs one-to-one communication with the portable terminal corresponding to the selected symbol. The method of claim 10, wherein the control unit, And a number is assigned to a group member in the PTT group communication in the PTT group communication mode. The method of claim 11, wherein the control unit, And assigning a number to a group member communicating with the PTT group in order of frequency of transmission and reception of a communication event. The method of claim 11, wherein the key input unit, Input a specific number among the numbers assigned to the members of the group, And the PTT module performs one-to-one communication with the mobile terminal corresponding to the input number. The method of claim 11, wherein the PTT module, When the one-to-one communication is performed, the mobile terminal other than the mobile terminal performing the one-to-one communication request the PTT server to proceed with the PTT group communication. The method of claim 14, wherein the PTT module, When the specific number is selected, the PTT server requests one-to-one communication with the mobile terminal corresponding to the selected number, and when accepting the one-to-one communication request from the mobile terminal corresponding to the selected number, the mobile terminal corresponding to the selected number And a one-to-one communication with the mobile terminal. The method of claim 10, wherein the PTT module, And returning to the PTT group communication after the one-to-one communication ends. The method of claim 11, wherein the PTT module, And requesting, by the PTT server, display units of the one-to-one communication terminals to be displayed in a reject state on the display unit of the portable terminals in the PTT group communication. The method of claim 11, wherein And a display unit for displaying the portable terminal in one-to-one communication with other portable terminals of the group member.

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