A device, comprising: a memory; and at least one processor configured to: transmit, to a first server, an allocation request requesting allocation of a group communication session with a plurality of devices; receive, from the first server, an allocation response in response to the allocation request, the allocation response including credential information for the device to use to join the group communication session, the credential information comprising a session key; transmit, to a second server, an allocation bind request with the credential information to join the group communication session; receive, from the second server, an allocation bind success response in response to the allocation bind request, the allocation bind success response indicating that the device has joined the group communication session; transmit a join notification to the plurality of devices via a third server to provide notification that the device has joined the group communication session; receive another join notification from at least one of the plurality of devices, the other join notification notifying the device that the at least one of the plurality of devices has joined the group communication session; transmit, to the second server, an information request requesting information on the at least one of the plurality of devices, wherein the information request includes the session key; and receive, from the second server, an information response responsive to the information request, the information response including the information on the at least one of the plurality of devices. a memory; and at least one processor configured to: transmit, to a first server, an allocation request requesting allocation of a group communication session with a plurality of devices; receive, from the first server, an allocation response in response to the allocation request, the allocation response including credential information for the device to use to join the group communication session, the credential information comprising a session key; transmit, to a second server, an allocation bind request with the credential information to join the group communication session; receive, from the second server, an allocation bind success response in response to the allocation bind request, the allocation bind success response indicating that the device has joined the group communication session; transmit a join notification to the plurality of devices via a third server to provide notification that the device has joined the group communication session; receive another join notification from at least one of the plurality of devices, the other join notification notifying the device that the at least one of the plurality of devices has joined the group communication session; transmit, to the second server, an information request requesting information on the at least one of the plurality of devices, wherein the information request includes the session key; and receive, from the second server, an information response responsive to the information request, the information response including the information on the at least one of the plurality of devices. transmit, to a first server, an allocation request requesting allocation of a group communication session with a plurality of devices; receive, from the first server, an allocation response in response to the allocation request, the allocation response including credential information for the device to use to join the group communication session, the credential information comprising a session key; transmit, to a second server, an allocation bind request with the credential information to join the group communication session; receive, from the second server, an allocation bind success response in response to the allocation bind request, the allocation bind success response indicating that the device has joined the group communication session; transmit a join notification to the plurality of devices via a third server to provide notification that the device has joined the group communication session; receive another join notification from at least one of the plurality of devices, the other join notification notifying the device that the at least one of the plurality of devices has joined the group communication session; transmit, to the second server, an information request requesting information on the at least one of the plurality of devices, wherein the information request includes the session key; and receive, from the second server, an information response responsive to the information request, the information response including the information on the at least one of the plurality of devices.