Method and apparatus for managing MCPTT service

1. A first MCPTT client for managing a Mission Critical Push-to-Talk (MCPTT) service, the first MCPTT client comprising:

a networking device; and

a processing unit configured to control the networking device to:

transmit an MCPTT request message to a second MCPTT client, and

receive, from the second MCPTT client, an MCPTT response message in response to the MCPTT request message,

wherein the MCPTT request message is one of an MCPTT call back request message requesting the second MCPTT client to place a first MCPTT call to the first MCPTT client or an MCPTT remotely initiated call request message allowing the second MCPTT client to initiate a second MCPTT call without the second MCPTT client's user initiating the second MCPTT call,

wherein the MCPTT call back request message comprises information for urgency level of the MCPTT call back request message and information for time of the MCPTT call back request message,

wherein the MCPTT remotely initiated call request message comprises an instruction on whether the second MCPTT client's user is notified or not, and

wherein the first MCPTT call and the second MCPTT call are established between the first MCPTT client and the second MCPTT client based on the MCPTT request message and the MCPTT response message.

2. The first MCPTT client of claim 1 ,

wherein the MCPTT call back request message includes priority information, and

wherein the MCPTT response message includes the priority information.

3. The first MCPTT client of claim 2 , wherein the second MCPTT client is notified to call back with the priority information including a time at which the first MCPTT client sent the MCPTT call back request message.

4. The first MCPTT client of claim 2 ,

wherein the second MCPTT client is configured to send an MCPTT call back response message after receiving an input from a user of the second MCPTT client,

wherein the MCPTT call back response message includes an indication corresponding to a calling back functionality, and

wherein the first MCPTT client notifies a user of the first MCPTT client with the indication corresponding to the calling back functionality, in response to the MCPTT call back request message sent to an MCPTT server.

5. The first MCPTT client of claim 1 , wherein the MCPTT remotely initiated call request message includes at least one of a private call, priority information, an implicit floor control, a notify indication, a not notify indication, or information related to call back to one of the first MCPTT client or a third MCPTT client.

6. The first MCPTT client of claim 5 , wherein the MCPTT response message includes at least one of the priority information or an implicit floor request.

7. The first MCPTT client of claim 5 ,

wherein the MCPTT response message is sent autonomously by the second MCPTT client without obtaining an input from a user of the second MCPTT client when the MCPTT remotely initiated call request message includes the not notify indication, and

wherein the MCPTT response message is sent after receiving the input from the user of the second MCPTT client, when the MCPTT remotely initiated call request message includes the notify indication.

8. The first MCPTT client of claim 1 , wherein the first MCPTT client is configured to notify a user of the first MCPTT client with an indication of the MCPTT response message, in response to the MCPTT remotely initiated call request message sent to an MCPTT server.

9. The first MCPTT client of claim 1 , wherein the MCPTT remotely initiated call request message includes at least one of a private call, priority information, an implicit floor control, a notify indication, a not notify indication, or a group identifier (ID).

10. The first MCPTT client of claim 9 ,

wherein the MCPTT response message includes at least one of the priority information, the group ID, or an implicit floor request, and

wherein an MCPTT server is configured to identify one or more MCPTT clients in a group associated with the group ID.

11. The first MCPTT client of claim 10 , wherein the MCPTT server is configured to notify one or more users of the one or more MCPTT clients with an indication of the MCPTT response message, in response to the MCPTT remotely initiated call request message sent by the MCPTT server.

12. The first MCPTT client of claim 9 , wherein the MCPTT response message is sent autonomously by the second MCPTT client without obtaining an input from a user of the second MCPTT client when the MCPTT remotely initiated call request message includes the not notify indication.

13. The first MCPTT client of claim 9 ,

wherein the MCPTT response message is sent after receiving an input from a user of the second MCPTT client, when the MCPTT remotely initiated call request message includes the notify indication, and

wherein the first MCPTT client is configured to notify a user of the first MCPTT client with an indication of the MCPTT response message, in response to the MCPTT remotely initiated call request message sent to an MCPTT server.

14. A method for managing a Mission Critical Push-to-Talk (MCPTT) service by the first MCPTT client, the method comprising:

transmitting an MCPTT request message to a second MCPTT client; and

receiving, from the second MCPTT client, an MCPTT response message in response to the MCPTT request message,

wherein the MCPTT request message is one of an MCPTT call back request message requesting the second MCPTT client to place a first MCPTT call to the first MCPTT client or an MCPTT remotely initiated call request message allowing the second MCPTT client to initiate a second MCPTT call without the second MCPTT client's user initiating the second MCPTT call,

wherein the MCPTT call back request message comprises information for urgency level of the MCPTT call back request message and information for time of the MCPTT call back request message,

wherein the MCPTT remotely initiated call request message comprises an instruction on whether the second MCPTT client's user is notified or not, and

wherein the first MCPTT call and the second MCPTT call are established between the first MCPTT client and the second MCPTT client based on the MCPTT request message and the MCPTT response message.

15. The method of claim 14 ,

wherein the MCPTT call back request message includes priority information, and

wherein the MCPTT response message includes the priority information.

16. The method of claim 15 , wherein the second MCPTT client is notified to call back with the priority information including a time at which the first MCPTT client sent the MCPTT call back request message.

17. The method of claim 15 ,

wherein the second MCPTT client is configured to send an MCPTT call back response message after receiving an input from a user of the second MCPTT client,

wherein the MCPTT call back response message includes an indication corresponding to a calling back functionality, and

wherein the first MCPTT client notifies a user of the first MCPTT client with the indication corresponding to the calling back functionality, in response to the MCPTT call back request message sent to an MCPTT server.

18. The method of claim 14 , wherein the MCPTT remotely initiated call request message includes at least one of a private call, priority information, an implicit floor control, a notify indication, a not notify indication, or information related to call back to one of the first MCPTT client or a third MCPTT client.

19. The method of claim 14 , wherein the first MCPTT client is configured to notify a user of the first MCPTT client with an indication of the MCPTT response message, in response to the MCPTT remotely initiated call request message sent to an MCPTT server.

20. The method of claim 14 , wherein the MCPTT remotely initiated call request message includes at least one of a private call, priority information, an implicit floor control, a notify indication, a not notify indication, or a group identifier (ID).