Patent ID: 8311567

Claim:
A method for managing a pre-established session in a push-to-talk over cellular (PoC) server, the method comprising the steps of: establishing a pre-established session between a PoC user equipment (UE) and the PoC server; determining if there is a pre-established session between the PoC UE and the PoC server when a PoC session invitation request message is received from a first PoC server; storing a pre-established session ID according to the pre-established session when there is the pre-established session; transmitting, to the PoC UE, a PoC session re-invitation request message including the pre-established session ID; transmitting, to the PoC UE, a connection message including a PoC session ID; and transmitting, to the inviting PoC client, a PoC session termination message including information for terminating PoC session between the inviting PoC UE and the PoC UE, when a PoC session termination request message is received from the PoC UE, wherein the PoC session termination request message includes the information for terminating PoC session between the inviting PoC UE and the PoC server, and information for maintaining the pre-established session between the PoC UE and the PoC server.