The present invention relates to a telecommunications apparatus and a method, a storage medium, and a program for determining whether or not an other side communicating apparatus is near in a network. In a transmitting apparatus, a transmitting unit transmits a sending-message, and a control unit receives a response message to the sending-message, which includes acknowledgement information based on shared data and transmission information in the sending-message. The transmitting apparatus also includes a first judging unit that judges whether a response time of the acknowledgement message is less than a predetermined time. A receiving apparatus includes a generating unit that generates the acknowledgment information and transmits the response message to the transmitting apparatus.