1. Field of the Invention
The invention relates to an apparatus for intercepting communication data of a communication terminal apparatus connected to a communication network such as the Internet, an Intranet, or the like.
2. Description of Related Art
Besides the techniques in the communication field that aim at the improvement of the ability and performance of communication, there are techniques which function as countermeasures or aim at the prevention of disaster and/or crime. The techniques providing countermeasures or aiming at the prevention of disaster and/or crime are mainly developed by request of public agencies. For example, such techniques include “immediate search of transmitter of emergency report”, “trace back”, “communication intercept”, and the like.
In recent years, in association with the development of the Internet and Intranets, techniques for performing voice communication by using those communication networks are proposed. That is, in recent years, in place of a voice communication network using a conventional fixed telephone network, voice communication by the Internet, an Intranet, or the like are used widely. Owing to the expansion of the voice communication using the Internet, an Intranet, and the like, the establishment of an integrated network which integratedly handles a voice and data has been realized.
Even in the integrated network, it is necessary to realize the functions sought by public agencies as mentioned above, that is, “immediate search of transmitter of emergency report”, “trace back”, “communication intercept”, and the like.
The communication intercepting technique used in the conventional fixed telephone network, however, cannot be applied to voice communication using the Internet, an Intranet, or the like due to the following reason.
In the voice communication of the fixed telephone network, a communication route is fixed for a period of time from a connection of a call to a release thereof. To intercept the communication using the fixed telephone network, therefore, it is sufficient to “fixedly” intercept the communication at a specific position on the communication route connecting two telephones to be observed.
In the communication using the Internet, an Intranet, or the like, on the other hand, communication data is transmitted and received in packets, and it's operation is based on an assumption that the communication route is dynamically changed even during connection of a call. Therefore, it is impossible to fixedly intercept the communication at a specific position.