Patent ID: 7697510

Claim:
A communication terminal device connected to a center device via an Internet Protocol (IP) network, the communication terminal device comprising: a microphone periodically picking up a sound automatically that is generated by the communication terminal device independent of communication with the center device; means for periodically picking up a non-audible audio frequency signal selected from the group consisting of a signal tone, a voice communication signal and a facsimile communication signal of a modem transmitted in the communication terminal device to a receiving device in accordance with a predetermined operation independent of communication with the center device; means for converting the picked up audio frequency signal into a digital audio signal; means for transmitting the converted digital audio signal to the center device via the IP network; means for storing a recording management table storing a pre-determined transmission time; and means for determining whether or not the transmission time stored in the recording management table has arrived, wherein when the transmission time stored in the recording management table has arrived, the audio frequency signal is converted into the digital audio signal and transmitted to the center device.