This invention is to enable transfer of a right to speak in an audio teleconference in view of usability. In this invention, a PoC server is introduced to achieve new functions, such as transfer of the right to speak, reservation to acquire the right to speak, and deprivation of the right to speak. The PoC server has a teleconference presence manager, a teleconference manager, and a teleconference audio communication manager. The right to speak is managed in a presence data storage of the teleconference presence manager. The teleconference presence manager directly manages the presence data storage, but the teleconference manager manages transfer of the right to speak. In addition, the teleconference manager manages reservation of the right to speak by a storage for a reservation list of the right to speak. The teleconference audio communication manager carries out routing of audio data. At that time, only audio data received from a user holding the right to speak is transferred.