Communication charge manageable digital communication unit and a method of managing communication charge

A communication unit in a digital data communication network in which communication charge data is transmitted to a calling side via a data communication line at the time of termination of the communication, said data communication line being capable of transferring data in a mode selected among a plurality of communication modes each having different data bit transfer rate, and said communication charge being determined depending on a selected communication mode for the communication, comprising:

• a communication terminal including a plurality of terminal units operable in differing communication modes, each terminal unit having a unique subaddress allotted thereto, and coupled to said data communication line via a first line;
• first detection means coupled to said first line for detecting communication charge data transmitted on said first line;
• generating means coupled to said first line and said communication terminal, for generating the unique subaddress allotted to a terminal unit requesting a calling in response to a call request from said terminal unit requesting the calling;
• second detection means for detecting the subaddress from said generating means and the communication mode selected;
• store means coupled to said first detection means and said second detection means for individually storing communication charge data for each respective subaddress;
• and
• updating means coupled to said first detection means, said second detection means and said storage means for updating the communication charge data corresponding to the subaddress thus detected and stored in said storage means by adding the communication charge data detected by said first detection means to the corresponding charge data stored in said storage means.

A communication unit in a digital data communication network in which communication charge data is transmitted to a calling side via a data communication line at the time of termination of a communication, comprising:

• a communication terminal coupled to said data communication line via a first line and capable of communication in a plurality of communication modes including communication modes having different data bit transfer rate;
• first detection means coupled to said first line for detecting a communication charge data transmitted on said first line;
• generating means coupled to said communication terminal for generating a mode identification data specifying a communication mode to be used in a requested communication upon a calling;
• second detection means for detecting the mode identification data generated by said generating means;
• storage means for individually storing communication charge data for each respective communication mode;
• and
• updating means coupled to said first detection means, said second detection means and said storage means, for updating communication charge data corresponding to the mode identification charge data detected by said first detection means to the corresponding communication charge data stored in said storage means.

A communication method in a digital data communication network transmitting communication charge information to a calling side at the time of communication termination via a data communication line, said communication network comprising communication terminals coupled to said data communication line via a first line, said method comprising the steps of:

• generated an identification information from among a plurality of predetermined identification information at the time of calling from one of said communication terminals;
• generating a unique subaddress allotted to said one of said communication terminals at the time of calling, said subaddress including a mode of communication to be employed at said one of said communication terminals;
• extracting the subaddress and the identification information;
• detecting the communication charge information at the time of communication termination;
• and
• updating a stored content of a memory region corresponding to said identification information and a stored content of a memory region corresponding to the subaddress in response to said detected communication charge information and said extracted identification information and subaddress, said step of updating including the steps of accessing the corresponding memory regions and adding said detected communication charge to the stored content of the corresponding memory regions.