Method and device for requesting permission to send media, and method and device for controlling Push-To service

1. A method for controlling transmission of media data, comprising:

initiating a session-based PT (Push-To) service between a PT client and a PT server that has established a PT session using Session Initiation Protocol (SIP) techniques;

starting, by the PT client, a timer when a media burst revoke message including time information is received from the PT server,

where the timer is a client-operated retry-after timer that operates during which the PT client cannot request a permission to send media data to the PT server, and

wherein the time information is a value of a server-operated retry-after timer;

receiving, by the PT client, a media burst idle message from the PT server after the client-operated retry-after timer is started,

wherein the media burst idle message is received from the PT server that has started a stop talking grace timer and that has received last media data and a media burst release message from the PT client before expiry of the stop talking grace timer; and

stopping, by the PT client, the client-operated retry-after timer before the client-operated retry-after timer expires, when the media burst idle message is received from the PT server, such that the PT client can request a permission to send media data to the PT server.

2. The method of claim 1 , wherein a value of the client-operated retry-after timer is set based on the time information included in the media burst revoke message.

3. The method of claim 2 , wherein the server-operated retry-after timer is a T 9 timer.

4. The method of claim 1 , further comprising:

transmitting, by the PT client, last media data and the media burst release message to the PT server,

wherein the transmitting step is performed after the client-operated retry-after timer is started but before the client-operated retry-after timer is stopped.

5. The method of claim 1 , further comprising;

transmitting, by the PT client, a media burst request message to the PT server, after the client-operated retry-after timer is stopped.

6. The method of claim 1 , wherein the client-operated retry-after timer is a T 12 timer.

7. A PT (Push-To) client device comprising:

a communication module to perform transmission and reception of signals and information;

at least one timer to perform timer operations; and

a controller that cooperates with a PT server in order to, initiate a session-based PT (Push-To) service between the PT client device and the PT server that has established a PT session using Session Initiation Protocol (SIP) techniques;

start the timer when a media burst revoke message including time information is received from the PT server, wherein the timer is a client-operated retry-after timer that operates during which the PT client device cannot request a permission to send media data to the PT server, and wherein the time information is a value of a server-operated retry-after timer;

receive a media burst idle message from the PT server after the client-operated retry-after timer is started, wherein the media burst idle message is received from the PT server that has started a stop talking grace timer and that has received last media data and a media burst release message from the PT client device before expiry of the stop talking grace timer; and

stop the client-operated retry-after timer before the client-operated retry-after timer expires, when the media burst idle message is received from the PT server, such that the PT client device can request a permission to send media data to the PT server.

8. The PT client device of claim 7 , wherein the client-operated retry-after timer is a T 12 timer.

9. The PT client device of claim 7 , wherein the controller is able to send a media burst request message to the PT server after the client-operated retry-after timer is stopped.

10. The PT client device of claim 7 , wherein the PT client device is a PoC (Push-to-talk over Cellular) client device.

11. The PT client device of claim 7 , wherein the server-operated retry-after timer is a T 9 timer.

12. A talk burst control method for a session-based PT (Push-To) service between a PT client and a PT server, the method comprising:

transmitting, by the PT client, a TBCP Talk Burst Request message for getting a permission to send a Media Burst to the PT server;

receiving, by the PT client, a TBCP Talk Burst Granted message in response to the TBCP Talk Burst Request message from the PT server;

transmitting, by the PT client, media data to the PT server,

wherein the media data is transmitted through a session between the PT client and the PT server;

receiving, by the PT client, a TBCP Talk Burst Revoke message including time information from the PT server;

starting, by the PT client, a timer when the TBCP Talk Burst Revoke message including the time information is received from the PT Server,

wherein the timer is a client-operated retry-after timer during which the PT client cannot request a permission to send media data to the PT server, and wherein the time information is a value of a server-operated retry-after timer; and

transmitting, by the PT client, last media data and a media burst release message to the PT server, wherein said transmitting step is performed after the client-operated retry-after timer is started but before the client-operated retry-after timer is stopped; and

stopping, by the PT client, the client-operated retry-after timer before the client-operated retry-after timer expires, when a TBCP Talk Burst idle message is received from the PT server, such that the PT client can request a permission to send media data to the PT server.

13. The method of claim 12 , wherein a value of the client-operated retry-after timer depends on the time information included in the TBCP Talk Burst Revoke message.

14. The method of claim 12 , wherein the server-operated retry-after timer is a T 9 timer.

15. The method of claim 12 , further comprising:

transmitting, by the PT client, a media burst request message to the PT server, after the client-operated retry-after timer is stopped.

16. The method of claim 12 , wherein the client-operated timer is a T 12 timer.