fig2 is a signaling diagram illustrating the flow of signaling messages in a first exemplary embodiment of the present invention . poc client a 31 and poc client b 32 are engaged in a person - to - person call under the control of a poc server 33 . person - to - person calls usually follow a communication pattern in which a first poc user talks and then the other poc user responds . thus , each poc client transmits every second talk burst . in the example shown in fig2 , the users alternate , their speech , with poc client a talking first , poc client b talking next , and then poc client a talking again , and so on . this embodiment takes this alternative speech pattern into account by accessing a communication pattern model or algorithm in the tbc mechanism in order to provide faster response time to the next talker . to improve the latency time for the predicted next talker , the invention provides the predicted next talker with a pre - granted permission to talk . the pre - granted permission to talk may be signaled from the poc server to the poc client using a new tbc protocol message during the idle - state when no voice is exchanged in the poc session , but the poc session is ongoing . thus , the poc client receiving media is always pre - granted permission to talk after the previous talk burst has ended ( i . e ., after the tb release message is received in the poc server ). the poc client handset may then indicate to the user that he has been given pre - granted permission to talk . when the poc client having the pre - granted permission to talk presses the ptt button , he is immediately given permission to talk without any additional signaling to the poc server . thus the sts delay time is greatly reduced . when the poc server receives media from the poc client having pre - granted permission to talk , the poc server sends a tb taken message to the other poc client indicating that the pre - granted poc client now has permission to talk , and forwards the media to the other poc client . the example illustrated in fig2 shows that an initial talk request from poc client a 31 may follow steps 34 - 38 , which are essentially the same as steps 14 - 18 of fig1 . following the tb release message 18 , however , instead of sending a tb idle indication to each poc client , the poc server 33 sends a tb idle indication 39 to poc client a 31 and a tb pre - granted message 41 to poc client b 32 . poc client b now has pre - granted permission to talk . thereafter , when poc client b presses the ptt button , user b immediately receives an rts indication and can immediately begin talking . when the voice stream 42 is received by the poc server , the poc server sends a tb taken message 43 to poc client a indicating that poc client b now has permission to talk , and forwards the media to poc client a . when poc client b 32 is finished talking and releases the ptt button , a tb release message 44 is sent to the poc server 33 . based on the predicted alternating speech pattern , the poc server 33 sends a tb idle indication 45 back to poc client b , and sends a tb pre - granted message 46 to poc client a . poc client a now has pre - granted permission to talk . thereafter , when poc client a presses the ptt button , user a immediately receives an rts indication and can immediately begin talking . when the voice stream 47 is received by the poc server , the poc server sends a tb taken message 48 to poc client b indicating that poc client a now has permission to talk , and forwards the media to poc client b . when poc client a 31 is finished talking and releases the ptt button , a tb release message 49 is sent to the poc server 33 . based on the predicted alternating speech pattern , the poc server 33 sends a tb idle indication 50 back to poc client a , and sends a tb pre - granted message 51 to poc client b . thus the method continues to alternate providing pre - granted permission to talk to each of the poc clients . it should be noted that in this scenario the voice stream itself has to trigger the radio access network to go from the dormant state to the active state ( if needed ). this delay will influence the turnaround time ( tat ), which is defined as the time period between the point in time when a poc user releases the ptt button and when the poc user can hear the other poc user begin to speak . however , a longer tat is typically less annoying than a longer sts . fig3 is a signaling diagram illustrating the flow of signaling messages in a second exemplary embodiment of the present invention . in this embodiment , a poc user engaged in a person - to - person call transmits two talk bursts in a row rather than alternating with the other poc user . the example illustrated in fig3 shows that an initial talk request from poc client a 31 may follow steps 34 - 37 . upon the transmission of the tb release message 38 , the poc server 33 sends a tb idle indication 39 to poc client a and a tb pre - granted message 41 to poc client b . thereafter , when poc client b presses the ptt button , user b immediately receives an rts indication and can immediately begin talking . when the voice stream 42 is received by the poc server , the poc server sends a tb taken message 43 to poc client a indicating that poc client b now has permission to talk , and forwards the media to poc client a . when poc client b 32 is finished talking and releases the ptt button , a tb release message 44 is sent to the poc server 33 . based on the predicted alternating speech pattern , the poc server 33 sends a tb idle indication 45 back to poc client b , and sends a tb pre - granted message 46 to poc client a . poc client a now has pre - granted permission to talk . thereafter , poc client b unexpectedly presses the ptt button and sends a tb request message 53 to the poc server . in this embodiment , the poc server immediately sends a tb granted message 54 to poc client b , granting permission to talk . the poc server also sends a tb taken message 55 to poc client a , essentially rescinding the pre - granted permission to talk and informing poc client a that another poc client now has permission to talk . when the poc server receives the voice stream 56 from poc client b , the poc server forwards the voice stream to poc client a . fig4 is a signaling diagram illustrating the flow of signaling messages in a third exemplary embodiment of the present invention . in this embodiment , like fig3 , a poc user engaged in a person - to - person call transmits two talk bursts in a row rather than alternating with the other poc user . the steps of this embodiment are the same as fig3 from step 34 through step 53 when poc client b unexpectedly presses the ptt button and sends a tb request message 53 to the poc server . in this embodiment , the poc server first sends a tb taken message 58 to poc client a , essentially revoking the pre - granted permission to talk and informing poc client a that another poc client now has permission to talk . the poc server then waits for poc client a to return a tb acknowledgment message 59 before sending a tb granted message 60 to poc client b , granting permission to talk . when the poc server receives the voice stream 61 from poc client b , the poc server forwards the voice stream to poc client a . in another embodiment , the users may be engaged in a group communication . one of the users may be a prioritized poc user , who may be a dispatcher or the group owner . the object of this embodiment is to optimize the sts delay of the prioritized poc user . the solution provided by this embodiment is that the prioritized poc user is always given pre - granted permission to talk upon the completion of a talk burst , regardless of whom was sending the completed talk burst . fig5 is a signaling diagram illustrating the flow of signaling messages in a fourth exemplary embodiment of the present invention . in this embodiment , poc client a 63 and poc client b 64 are engaged in a person - to - person call under the control of a poc server 65 . the example begins at step 66 , where poc client a experiences a very short sts delay because he has been pre - granted permission to talk in previous steps not shown in fig5 , but shown for example , in fig2 - 4 . the voice stream 67 is then transmitted to poc client b 64 until poc client a finishes talking and sends a tb release message 68 to the poc server 33 . the poc server then follows the person - to - person speech pattern model , which assumes that the poc clients will alternate speaking . thus , a tb idle message 69 is sent to poc client a , and a tb pre - granted message 71 is sent to poc client b . simultaneously , the poc server starts a pre - granted permission timer , which expires at 72 . the timer measures a maximum duration of the pre - granted permission to speak . the typical person - to - person speech pattern model first expects a reply on each talk burst , but if no reply is given after a certain time interval , there is equal probability that the next talk burst will come from poc client a or poc client b . therefore , upon expiry of the timer , the poc server sends a tb revoke message 73 to poc client b revoking the pre - granted permission to speak . the poc server also sends another tb idle message 74 to poc client a because poc client b must acknowledge the tb revoke message before the poc server can conclude that the pre - granted permission to speak is removed . in the illustrated embodiment , poc client b acknowledges the tb revoke message with a tb release message 75 . as illustrated , after the expiry of the timer and the revocation of the pre - granted permission to speak , poc client b 64 sends a tb request message 76 requesting permission to speak . the poc server 33 returns a tb granted message 77 to poc client b . the poc server also sends a tb taken message 78 to poc client a 63 notifying poc client a that poc client b has been granted the right to speak . thereafter , the radio bearer between the clients is activated , and the voice stream 79 is carried from poc client b to poc client a . when poc client b releases the ptt button , a tb release message 80 is sent to the poc server . the poc server then sends a tb idle message 81 to poc client b , and sends a tb pre - granted message 82 to poc client a . in one embodiment , a tb pre - granted indication is included in the tb idle message . the poc server “ pumps ” tb idle messages to all poc clients during the idle period so the tb revoke message 73 sent to remove the pre - granted permission may be sent instead of a tb idle message and thus not create extra traffic . it should be noted that the reply ( here the tb release message 75 ) creates one extra message in the uplink . however , if tbc protocol messages are sent reliable ( for example using tcp ), the tb release message may be removed . it should also be noted that the pre - granted permission timer may be utilized for both person - to - person calls as well as group communications and prioritized users . the timer may be utilized to revoke the pre - granted permission to talk whenever the user with the pre - granted permission waits too long to begin talking . fig6 is a simplified block diagram of a poc server 33 modified in accordance with the apparatus of the present invention . in addition to the normal means for communicating with clients and forwarding media , the poc server includes a pre - granted permission timer 84 , a pre - granted selector 85 containing a communication pattern model 86 , and a tb granted controller 87 . when poc client a finishes talking , a tb release message 88 is sent to the poc server . the message is routed to the pre - granted selector 85 , which uses the communication pattern model 86 to issue a tb pre - granted message 89 to poc client b and a tb idle message 91 to poc client a . when poc client b finishes talking , a tb release message 92 is sent to the poc server . the message is routed to the pre - granted selector , which uses the communication pattern model to issue a tb pre - granted message 93 to poc client a and a tb idle message 94 to poc client b . if poc client b then requests to speak out of turn , the poc server receives a tb request message 95 from poc client b . this message is routed to the tb granted controller 87 . the tb granted controller issues a tb granted message 96 to poc client b and revokes the pre - granted permission given to poc client a by sending a tb taken message to poc client a , as shown in the embodiments of fig3 and 4 . those skilled in the art will readily appreciate that the present invention may be implemented using either hardware , or software , or both , and further , software implementations may vary using different languages and data structures . the present invention is not limited to a specific language and / or class of languages , nor is it limited to any single data structure implantation . the present invention may of course , be carried out in other specific ways than those herein set forth without departing from the essential characteristics of the invention . the present embodiments are , therefore , to be considered in all respects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein .