KR102642214B1 - Method for providing push-to-talk communication service and apparatus therefor - Google Patents

Abstract

A method and device for providing PTT communication service are disclosed. According to one embodiment, a method and device for providing a PTT communication service according to an embodiment are provided by a mobile radio that determines in real time whether the other party to whom the mobile radio wants to talk is logged on to the mobile PTT service provided by the PTT server. It provides a member registration confirmation function that displays, and a group/all call function during individual calls that allows group or all calls during individual calls between mobile radios.

Description

{Method for providing push-to-talk communication service and apparatus therefor}

The present invention relates to wireless communication technology, and more specifically to multi-call support radio technology.

Since the radio is designed to transmit signals in both directions between two communicating points, while sending a signal at one point, only reception of the signal is possible at the other point. In order for the receiving side to send a signal, a button input is required. It uses a communication method of the Push-to-talk (PTT) function, which requires explicitly changing the transmission direction.

Compared to mobile phones, a walkie-talkie has a smaller time difference between the time the call is made by the transmitter and the time the call is received by the receiver. In other words, there is no need to connect the call and ring the bell like with a mobile phone. For example, if the calling party speaks by pressing the radio PTT, the caller's voice can be heard from the radio speaker on the receiving party within a short period of time.

As such, the number of users of walkie-talkie radios is increasing due to their ease of use and low cost, and when you press PTT to transmit, the corresponding voice is immediately heard on the receiving radio, which is very useful.

According to one embodiment, a method and device for providing a PTT communication service that supports a member registration confirmation function and a group/all call function during an individual call are proposed.

A method of providing a PTT communication service according to an embodiment includes the steps of the PTT server receiving a PTT communication service registration request message from a first mobile radio, verifying the PTT communication service registration request, and completing the PTT communication service registration if verification is successful. It includes transmitting a message to the first mobile radio, and transmitting a service list including the activity status of group members registered in the PTT communication service provided by the PTT server to the first mobile radio.

The PTT communication service registration request message may include the IMEI number, name, and group name of the mobile radio.

The service list may include a service name, group name, and member list, and the member list may include the log-on status and log-off status of group members using the PTT communication service.

The PTT communication service providing method may further include transmitting a message informing group members of the log-on status of the first mobile radio.

The method of providing a PTT communication service may further include the step of transmitting a message notifying the log-off status of the first mobile radio to PTT communication service members when the first mobile radio registered in the PTT communication service is turned off.

The method of providing a PTT communication service may further include the step of transmitting a message notifying the log-on status of the second mobile radio to the first mobile radio when a second mobile radio that is not registered in the PTT communication service is registered in the PTT communication service. You can.

A method of providing a PTT communication service includes receiving a PTT individual call request for a second mobile radio registered in the PTT communication service from a first mobile radio registered in the PTT communication service, and receiving a PTT individual call request from the first mobile radio. It may further include transmitting to a second mobile radio and controlling an individual call connection between the first mobile radio and the second mobile radio.

The PTT communication service provision method includes receiving a group call request from a third mobile radio during a PTT individual call between a first mobile radio and a second mobile radio, and transmitting the group call request to the first mobile radio and the second mobile radio. The method may further include controlling a group call connection between groups including a first mobile radio, a second mobile radio, and a third mobile radio.

A method of providing a PTT communication service includes the steps of receiving a PTT individual call request between a first mobile radio and a second mobile radio of a third mobile radio during a PTT individual call between a first mobile radio and a second mobile radio, and the third mobile radio. It may further include controlling an additional individual call connection of the radio with the first mobile radio or the second mobile radio.

A method of receiving a PTT communication service according to another embodiment includes the steps of a mobile radio requesting PTT communication service registration to a PTT server, receiving a PTT communication service registration completion message from the PTT server, and registering a PTT communication service in the PTT communication service. It includes receiving a service list including the activity status of group members from the PTT server, and displaying the received service list.

In the step of displaying the service list, the log-on and log-off status of group members using the PTT communication service can be displayed.

The method of receiving PTT communication service may further include the step of immediately outputting a call-unable tone from the mobile radio itself when a call is requested to a group member in a logged-on state.

The PTT communication service reception method includes the steps of receiving a group call request for a new mobile radio from the PTT server during a PTT individual call with another mobile radio, and mixing and outputting the existing call voice and the new voice call voice during the group call. It may further include.

The PTT server according to another embodiment includes a service register that verifies the PTT communication service registration request from the first mobile radio and transmits a PTT communication service registration completion message to the first mobile radio when verification is successful, and registers in the PTT communication service. A call connection control unit that controls call connections between group members, a list management unit that manages a service list containing the activity status of group members for the PTT communication service provided by the PTT server, and a service list that transmits and receives messages. It includes a communication unit that transmits to the first mobile radio.

When receiving a group call request from a third mobile radio during a PTT individual call between the first mobile radio and the second mobile radio, the call connection control unit transmits the group call request to the first mobile radio and the second mobile radio, and transmits the group call request to the first mobile radio and the second mobile radio. You can control group call connections between groups including mobile radios, second mobile radios, and third mobile radios.

According to the PTT communication service provision method and device according to an embodiment, member registration that displays on the mobile radio in real time whether the other party the mobile radio wants to call is logged on to the mobile PTT service provided by the PTT server. By providing a confirmation function, mobile radio users can check logged on members through the member registration confirmation function, so there is no need to make a call to the other party they want to call. Even if a call is made, the mobile radio itself immediately displays that the call is not available, allowing the user to confirm that the other party is not logged on. Accordingly, network traffic can be reduced and the processing burden on the PTT server can be reduced.

In addition, the method and device for providing PTT communication service enable individual/group/all calls at the same time even during individual calls between mobile radios, so users can use the PTT call service at any time.

1 is a diagram illustrating the configuration of a PTT communication service providing system according to an embodiment of the present invention;
Figure 2 is a diagram showing the detailed configuration of a PTT server according to an embodiment of the present invention;
Figure 3 is a diagram illustrating a screen of a mobile radio that provides a member registration confirmation function according to an embodiment of the present invention;
Figure 4 is a diagram illustrating the concept of the group/all call function during an individual call according to an embodiment of the present invention;
Figure 5 is a diagram showing an example of using the Compact VoIP protocol according to an embodiment of the present invention;
6 is a diagram illustrating a member registration confirmation process according to an embodiment of the present invention;
7 is a diagram illustrating a service list according to an embodiment of the present invention;
Figure 8 is a diagram illustrating a multi-currency process according to an embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to provide common knowledge in the technical field to which the present invention pertains. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In describing the embodiments of the present invention, if it is judged that a detailed description of a known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted, and the terms described below will be used in the embodiments of the present invention. These are terms defined to reflect the function of and may vary depending on the user's or operator's intention or customs. Therefore, the definition should be made based on the contents throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention illustrated below may be modified into various other forms, and the scope of the present invention is not limited to the embodiments detailed below. Examples of the present invention are provided to more completely explain the present invention to those skilled in the art.

Figure 1 is a diagram illustrating the configuration of a push-to-talk (PTT) communication service provision system according to an embodiment of the present invention.

Referring to FIG. 1, the PTT communication service providing system 1 includes a PTT server 2 and a plurality of mobile radios 3. Figure 1 shows n mobile radios (3-1, 3-2, 3-3, ..., 3-n).

The mobile radio (3) is an IP-based Push To Talk (IP-PTT) device that provides 1:1 and 1:N voice services using Internet Protocol (IP) in a mobile communication network. am. Mobile communication networks can be 3G, LTE (Long Term Evolution), 4G, 5G, Wi-Fi, etc.

The voice service is a PTT service that provides voice signals to the mobile radio (3) using the PTT function based on VoIP (Voice Over Internet Protocol) service provided using IP technology. VoIP service is a packet data communication that carries voice signals as packet data between mobile radios (3). The PTT service enables easy and fast communication by pressing the PTT button, which is a button to switch between sending and receiving, and speaking, without going through processes such as dialing or making a phone call. The PTT button with a call sending/receiving switching function can be replaced with a VOX (Voice activated Transmission) function. Meanwhile, although the description was limited to voice call services, it can be expanded to other communication services such as text messaging services.

The PTT server (2) sets up a call between the sending mobile radio and the receiving mobile radio and forms a voice call channel to provide a voice call service between the mobile radios. The PTT server (2) can be connected to the mobile radio (3) through an Internet network. The receiving mobile radio may be individual or multiple in a group.

The PTT server 2 according to one embodiment provides a member registration confirmation function and individual/group/all call functions during individual calls.

The member registration confirmation function is a function that displays on the mobile radio (3) in real time whether the other party to whom the mobile radio (3) wants to talk is logged on to the mobile PTT service provided by the PTT server (2). Since the user of the mobile radio (3) can check the logged on member through the member registration confirmation function, there is no need to make a call to the other party. Even if a call is made, the mobile radio 3 itself immediately indicates that the call is not available, allowing the user to confirm that the other party is not logged on. Accordingly, network traffic can be reduced and the processing burden on the PTT server 2 can be reduced.

The individual/group/all call function during an individual call is a function that allows individual/group/all calls during an individual call between mobile radios. Since general SIP-based mobile radios do not support additional individual or group call services during an individual call, the previous individual call must be terminated to make an additional individual call, group call, or general call. In contrast, since the individual/group/all call function during an individual call according to one embodiment applies the Compact VoIP protocol, additional individual calls, group calls, or all calls are possible at the same time even during an individual call, so the user can make a PTT call. The service is always available.

Figure 2 is a diagram showing the detailed configuration of a PTT server according to an embodiment of the present invention.

Referring to Figures 1 and 2, the PTT server 2 includes a processor and a communication unit 24, and the processor includes a service registration unit 21, a list management unit 22, and a call connection control unit 23.

The communication unit 24 transmits and receives messages with a mobile radio connected to the PTT server 2.

Upon receiving a PTT communication service registration request from a predetermined mobile radio, for example, the first mobile radio (3-1), through the communication unit 24, the service registration unit 21 verifies the PTT communication service registration request and performs verification. If successful, a PTT communication service registration completion message is generated and transmitted to the first mobile radio (3-1) through the communication unit (24). The PTT communication service registration request message may include the IMEI number, name, and group name of the mobile radio.

The list management unit 22 manages a service list including the activity status of group members for the PTT communication service provided by the PTT server 2. The service list includes a service name, group name, and member list, and the member list may include the activity status including the log-on status and log-off status of group members using the PTT communication service.

When the list management unit 22 processes service registration according to the service registration request of the first mobile radio 3-1, it generates a message notifying the log-on status of the first mobile radio 3-1, and sends it to the communication unit ( 24), it can be transmitted to the second mobile radio (3-2) and the third mobile radio (3-3), which are group members.

When the first mobile radio (3-1) registered in the PTT communication service is turned off, the list management unit 22 generates a message notifying the log-off status of the first mobile radio (3-1), and sends it to the communication unit 24 ) can be transmitted to the second mobile radio (3-2) and the third mobile radio (3-3), which are PTT communication service members.

When a second mobile radio (3-2) that is not registered in the PTT communication service is registered in the PTT communication service, the list management unit 22 generates a message notifying the log-on status of the second mobile radio (3-2), This can be transmitted to the first mobile radio (3-1) through the communication unit 24.

The call connection control unit 23 controls call connections between group members registered in the PTT communication service. At this time, call connection includes individual calls, group calls, and all calls.

For example, in an individual call, the call connection control unit 23 connects the first mobile radio (3-1) registered to the PTT communication service through the communication unit 24 to the second mobile radio (3-2) registered to the PTT communication service. When receiving a PTT individual call request for, the PTT individual call request of the first mobile radio (3-1) is transmitted to the second mobile radio (3-2) through the communication unit (24), and the first mobile radio (3-1) -1) and controls the individual call connection of the second mobile radio (3-2).

For example, in a group call, the call connection control unit 23 requests a group call from the third mobile radio (3-3) during a PTT individual call between the first mobile radio (3-1) and the second mobile radio (3-2). When received through the communication unit 24, a group call request message is generated and delivered to the first mobile radio (3-1) and the second mobile radio (3-2) through the communication unit 24, and the first mobile radio (3-1) is transmitted to the second mobile radio (3-1). Controls group call connections between groups including the mobile radio (3-1), the second mobile radio (3-2), and the third mobile radio (3-3).

In comparison, during a PTT individual call between the first mobile radio (3-1) and the second mobile radio (3-2), the first mobile radio (3-1) or the second mobile radio of the third mobile radio (3-3) When a request for an individual call with the radio (3-2) is received through the communication unit 24, the call connection control unit 23 generates an individual call request message, which the third mobile radio (3-3) wishes to call. 1 is transmitted to the mobile radio (3-1) or the second mobile radio (3-2) through the communication unit 24, and the first mobile radio (3-1) or the second of the third mobile radio (3-3) Controls additional individual call connections with mobile radios (3-2).

Figure 3 is a diagram illustrating a screen of a mobile radio that provides a member registration confirmation function according to an embodiment of the present invention.

Referring to Figures 1 and 3, the mobile radio 3 provides activity information, including whether members registered in the PTT server 2 are logged on, through a member registration confirmation function. For example, as shown in FIG. 3, on the screen of the mobile radio 3, members (ChaYJ, LeeJH) currently logged on to the service, as indicated by reference numerals 310 and 320, can be distinguished from members who have logged off. Display the icon.

If the calling member wants to make a call to a called member who is not logged on, the mobile radio 3 does not make a call to the called member, and the mobile radio 3 itself can inform the called member that the call is unavailable. The general method is that the calling member calls and informs the called member that the call is unavailable if the called member does not answer the phone. However, according to the present invention, the calling member's mobile radio itself announces that the call is unavailable without the calling member making a call. There is a difference in

Figure 4 is a diagram illustrating the concept of a group/all call function during an individual call according to an embodiment of the present invention.

More specifically, Figure 4 shows that during an individual call between team member A holding a first mobile radio (3-1) and team member B holding a second mobile radio (3-2), the third mobile radio (3-3) ) shows a scenario in which a manager (team leader) holding a phone number requests a group call from group members.

In a typical PTT service, the manager cannot call a group member during an individual call between team members A and B. In other words, a group call is possible after the call between A and B ends.

However, the PTT service according to one embodiment allows simultaneous group calls at the request of the manager (team leader) even during individual calls between team members A and B. At this time, A hears B's voice and the Manager's voice together.

Figure 5 is a diagram illustrating an example of using the Compact VoIP protocol according to an embodiment of the present invention.

The PTT server according to one embodiment does not follow SIP (Session Initiation Protocol: RFC3261), a VoIP-related standard, but follows the Compact VoIP protocol based on 1:N communication. The Compact VoIP protocol has a fast response time due to fewer transactions and provides excellent performance, especially for multi-party calls. Based on the Compact VoIP protocol, it can provide two-way HD Voice, standardized text transmission and reception, and rich voice recording functions. In addition, it is convenient to use as it provides real-time information on whether the service member is registered with the PTT server. It is easy to install, operate and maintain, and the service fee is economical.

According to the Compact VoIP protocol, when the first mobile radio (3-1) presses the PTT button (PTT press) and requests a call connection with the second mobile radio (3-2) (TALKreq) (510), the PTT server ( 2) transmits a call connection response (TALKcfm) (520) to the first mobile radio (3-1) and requests a call connection to the second mobile radio (3-2) (TALKind) (530). Accordingly, an individual call is made between the first mobile radio (3-1) and the second mobile radio (3-2) (540).

Subsequently, when the first mobile radio (3-1) releases the PTT button (PTT release), the communication connection between the first mobile radio (3-1) and the second mobile radio (3-2) is released (RELEASE )(550).

Figure 6 is a diagram illustrating a member registration confirmation process according to an embodiment of the present invention.

Referring to FIG. 6, the first mobile radio (3-1) includes its IMEI number (865036049474784), name (ChaYJ), and group name (Development Team) in the service registration request (RequestReq) message to request service registration. and transmits it to the PTT server (2) (601).

The PTT server 2 checks and verifies this and, if it is a normal request, delivers a registration completion (RegisterCfm) message to the first mobile radio 3-1 (602).

Subsequently, the PTT server 2 transmits service information (full call service name, group name/member list) to the first mobile radio 3-1 as a NotifyList (service list) (604), and the second group member A message (NotifyLogOn) notifying the log-on status of the first mobile radio (3-1) is delivered to the mobile radio (3-2) and the third mobile radio (3-3) (603). The service list will be described later with reference to FIG. 7.

When the registered first mobile radio (3-1) presses the PTT button (611) and requests (TALKreq) (612) a private call connection with the second mobile radio (3-2), the PTT server (2) A call connection response (TALKcfm) (613) is transmitted to the first mobile radio (3-1), and an individual call connection is requested to the second mobile radio (3-2) (TALKind) (614). Accordingly, an individual call connection is established between the first mobile radio (3-1) and the second mobile radio (3-2) (615).

During an individual call between the first mobile radio (3-1) and the second mobile radio (3-2), the third mobile radio (3-3) presses the PTT button (PTT press) (621), and the PTT server (2) When a group call connection request (TALKreq (group)) 622 is made, the PTT server (2) sends a group call connection request (TALKind) to the first mobile radio (3-1) and the second mobile radio (3-2). and transmit (623, 624) respectively, and transmit the call response (TALKcfm) to the third mobile radio (3-3) (625). Accordingly, during an individual call between the first mobile radio (3-1) and the second mobile radio (3-2), a group call connection with the third mobile radio (3-3) is established (626).

Figure 7 is a diagram illustrating a service list according to an embodiment of the present invention.

Referring to Figure 7, NotifyList (service list) includes a service name, group name, and member list. The member list includes the log-on status and log-off status of group members using the PTT communication service.

For example, in Figure 7, you can see that the full call service name is service,jcore,jcore, and the group name is composed of Management Team, Development Team, Production Team, Marketing Team, and After Service Team.

You can see that subscriber ChaYJ is the Development Team, members logged on to the service are ChaYJ, LeeJH, and Hwan is logged off.

If subscriber ChaYJ powers off, the log-off status is displayed by sending NotifyList(ChaYJ, 0) to the service (jcore) member. If Hwan powers on and registers in the PTT server (2), the log-off status is displayed. The log-on status is notified by passing it to NotifyList(Hwan, 1).

Figure 8 is a diagram illustrating a multi-currency process according to an embodiment of the present invention.

In the existing SIP-based PTT service, as with mobile phones, additional new calls (group calls or general calls) cannot be made while in an individual call state, so a new call must be made after the call ends or a new call must be made after the existing individual call has ended. .

In comparison, the PTT service according to one embodiment allows multiple calls at the same time rather than activating only one call, so that new calls (group calls, all calls) are made even in existing individual calls. At this time, voice processing (voice from existing calls and voice from new calls) is mixed in the mobile radio itself.

More specifically, as shown in FIG. 8, the first mobile radio (3-1) requests a call connection with the second mobile radio (3-2) (GRAB_REQ (PTT #2) (801) to the PTT server ( 2), the PTT server 2 transmits the call connection request (GRAB_IND (PTT #1)) of the first mobile radio (3-1) to the second mobile radio (3-2) (802). PTT The server (2) transmits (803) a connection request success message (GRAB_SUCCESS) to the first mobile radio (3-1), and establishes an individual connection between the first mobile radio (3-1) and the second mobile radio (3-2). The call is connected (804).

Subsequently, during an individual call between the first mobile radio (3-1) and the second mobile radio (3-2), when the third mobile radio (3-3) requests a group call connection (GRAB_REQ (GroupCall)) (811), , the PTT server (2) transmits a group call request (GRAB_IND (GroupCall)) to the first mobile radio (3-1) and the second mobile radio (3-2), respectively (812, 813). Next, the PTT server ( 2) transmits (814) a connection request success message (GRAB_SUCCESS) to the third mobile radio (3-3), and the first mobile radio (3-1), the second mobile radio (3-2), and the third mobile A group call is made between radios (3-3) (815). In this process (810), the group call requested by the third mobile radio (3-3) is performed even when the second mobile radio (3-2) is on an individual call. is a process of allowing. At this time, the second mobile radio (3-2) refers to the source and mixes the voice of the first mobile radio (3-1) and the voice of the third mobile radio (3-3).

In comparison, during an individual call between the first mobile radio (3-1) and the second mobile radio (3-2), the third mobile radio (3-3) sends the second mobile radio (3-2) to the PTT server (2). ), the PTT server (2) creates an individual call request message with the second mobile radio (3-2), delivers it to the second mobile radio (3-2), and sends it to the third mobile radio (3-2). Controls additional individual call connection of the radio (3-3) with the second mobile radio (3-2).

So far, the present invention has been examined focusing on its embodiments. A person skilled in the art to which the present invention pertains will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

Claims (15)

In a method of providing a Push To Talk (PTT) communication service, a PTT server,
Receiving a PTT communication service registration request message from a first mobile radio;
Verifying the PTT communication service registration request and, if verification is successful, transmitting a PTT communication service registration completion message to the first mobile radio;
Transmitting a service list including the activity status of group members registered in the PTT communication service provided by the PTT server to the first mobile radio; and
Controlling the connection so that a group call or an entire call can be made simultaneously during an individual call between mobile radios;
A PTT communication service providing method comprising: The method of claim 1, wherein the PTT communication service registration request message is
A method of providing PTT communication service, characterized by including the IMEI number, name, and group name of the mobile radio. According to claim 1, the service list is
Contains service name, group name, and member list,
A method of providing a PTT communication service, wherein the member list includes the log-on status and log-off status of group members using the PTT communication service. According to claim 1, the method of providing PTT communication service is
transmitting a message informing group members of the log-on status of the first mobile radio;
A PTT communication service providing method further comprising: According to claim 1, the method of providing PTT communication service is
When the first mobile radio registered in the PTT communication service is powered off, transmitting a message notifying the log-off status of the first mobile radio to the PTT communication service members;
A PTT communication service providing method further comprising: According to claim 1, the method of providing PTT communication service is
When a second mobile radio that is not registered in the PTT communication service is registered in the PTT communication service, transmitting a message notifying the log-on status of the second mobile radio to the first mobile radio;
A PTT communication service providing method further comprising: According to claim 1, the method of providing PTT communication service is
Receiving a PTT individual call request for a second mobile radio registered in the PTT communication service from a first mobile radio registered in the PTT communication service;
Transferring a PTT individual call request from a first mobile radio to a second mobile radio;
Controlling individual call connections between the first mobile radio and the second mobile radio;
A PTT communication service providing method further comprising: The method of claim 1, wherein controlling the connection comprises
Receiving a group call request from a third mobile radio during a PTT individual call between a first mobile radio and a second mobile radio;
Forwarding a group call request to a first mobile radio and a second mobile radio; and
Controlling a group call connection between a group including a first mobile radio, a second mobile radio, and a third mobile radio;
A PTT communication service providing method comprising: The method of claim 1, wherein controlling the connection comprises
Receiving a PTT individual call request from a third mobile radio with the first or second mobile radio during a PTT individual call between the first mobile radio and the second mobile radio; and
Controlling an additional individual call connection of the third mobile radio with the first or second mobile radio;
A PTT communication service providing method comprising: In a method of receiving PTT communication service, a mobile radio,
Requesting PTT communication service registration to a PTT server;
Receiving a PTT communication service registration completion message from the PTT server;
Receiving a service list including the activity status of group members registered in the PTT communication service from the PTT server;
displaying a list of received services; and
When a call request is made to a group member whose activity state is logged off, immediately outputting a call unavailable tone from the mobile radio itself without making a call;
A PTT communication service reception method comprising: The method of claim 10, wherein the step of displaying the service list includes
A PTT communication service reception method characterized by displaying the log-on and log-off status of group members using the PTT communication service. delete The method of claim 10, wherein the method of receiving PTT communication service is
Receiving a group call request for a new mobile radio from the PTT server during a PTT individual call with another mobile radio; and
Mixing and outputting existing call voice and new voice call voice during a group call;
A PTT communication service reception method further comprising: a service register that verifies a PTT communication service registration request from the first mobile radio and, if verification is successful, transmits a PTT communication service registration completion message to the first mobile radio;
a call connection control unit that controls call connections between group members registered in the PTT communication service;
a list management unit that manages a service list including the activity status of group members for the PTT communication service provided by the PTT server; and
A communication unit that transmits and receives messages and transmits a service list to the first mobile radio; Includes,
The call connection control unit
A PTT server that controls the connection so that group calls or all calls can be made simultaneously during individual calls between mobile radios. The method of claim 14, wherein the call connection control unit
When a group call request from a third mobile radio is received during a PTT individual call between the first mobile radio and the second mobile radio, the group call request is transmitted to the first mobile radio and the second mobile radio, and the first mobile radio and the second mobile radio are transmitted to the group call request. A PTT server that controls group call connections between groups including mobile radios and third mobile radios.