Abstract:
A communication terminal apparatus is used in a network system in which a sub address is affixed to a subscriber apparatuses from each other. A proper incoming call indicating tone is registered beforehand in correspondence with a sub address, and an incoming call indicating tone which has been registered in accordance with the sub address is output when a terminating call is received. In consequence, a called terminal can be discriminated by the incoming call indicating tone. Further, a desired incoming call terminating tone can be heard.

Description:
CROSS REFERENCED RELATED APPLICATIONS 
     This application is a Continuation-In-Part of application Ser. No. 07/283,857 filed Dec. 13, 1988 abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a communication terminal apparatus, more particularly, to a communication terminal apparatus used in a network system operated with a subscriber number affixed with a sub address to enable a plurality of communication terminal apparatuses to be discriminated from each other. 
     2. Description of the Prior Art 
     Conventionally, communication terminal apparatuses (hereinafter referred to as terminals) such as telephones are used jointly by a plurality of users. However, incoming call indication ring of telephones or the like do not indicate which person is being called, and the user does not know the called person until he gets the call. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a improved communication terminal apparatus. 
     Another object of the present invention is to provide a communication terminal apparatus which is capable of eliminating the aforementioned problem of a conventional apparatus and which enables a desired ringing tone to be heard. 
     A further object of the present invention is to discriminate a sub address by the sub address discriminating means and to output an incoming call indicating tone from an incoming call indicating tone outputting means corresponding to the sub address when a terminating call is received. The proper incoming call indicating tone is registered beforehand by an incoming call indicating tone registration means in correspondence with the sub address. 
     A further object of the present invention is to provide a communication terminal apparatus in which a called person can be discriminated by the incoming call indicating tone and further, a desired incoming call indicating tone can be heard. 
     The above and other objects, advantages and features of the present invention will become more readily apparent from the following specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a digital telephone set used in an embodiment of the present invention; 
     FIG. 2 is an external view of the digital telephone set of FIG. 1; 
     FIG. 3 shows the connection of an ISDN; 
     FIG. 4 shows a number system for the ISDN; 
     FIG. 5 is a flow chart of an incoming call indication tone registration process; and 
     FIG. 6 is a flow chart of a ringing tone generating process. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention will be described in detail with reference to the accompanying drawings in which the communication terminal apparatus according to the present invention is applied to a digital telephone set connected to an integrated services digital network (ISDN) system. 
     Referring first to FIG. 3 which shows the connection of the ISDN system, a network termination 1 is connected to a plurality of terminal apparatuses 4 to 11 by an ISDN bus 2. The network termination 1 is connected to an ISDN switching system (not shown) by a subscriber line 3. The terminal apparatuses 4, 8, 10 and 11 comprise general digital telephone sets, the terminal apparatuses 5 and 9 comprise facsimile devices, the terminal apparatus 6 is a telex device, and the terminal apparatus 7 is digital telephone device of the present embodiment. 
     FIG. 2 shows the external view of the digital telephone set of the present embodiment. In FIG. 2, the digital telephone set has a digital telephone set body 21, a handset 22, key buttons 23 from which a telephone number or the like is input, and a speaker 24 for producing an incoming call indication tone or the like. 
     FIG. 1 is a block diagram of the digital telephone set of the present embodiment, showing the structure thereof. The digital telephone set includes a micro processing unit 31 (hereinafter referred to as an MPU) for controlling the digital telephone set in accordance with a predetermined control program, an internal bus 32 for the MPU 31, a ROM 33 for storing the control program, a memory 34 for storing a registered incoming call indicating tone, the memory 34 also serving as an auxiliary memory, a sound converting unit 35 (hereinafter referred to as a CODEC), a handset 36, a speaker 37, a key operation unit 38 (hereinafter referred to as an OPU), a communication control unit (hereinafter referred to as a CCU), and an ISDN bus 40. A power source (not shown) supplies power to the units of FIG. 1 independent of hook state as is well known in the art. 
     FIG. 4 shows a number system used in the ISDN. The number includes a subscriber number portion F1, and a sub address portion F2. 
     Next, the operation of this embodiment will be described. 
     FIG. 5 is a flow chart of the operation of registering an incoming call indicating tone which corresponds to a sub address. First, connection/disconnection of a hook switch which is attained by lifting up or placing the handset 36 is detected in step S1. If it is detected that the switch has been connected, the flow goes to a normal call origination processing. If it is detected that the switch is disconnected, it is detected whether or not the key operation needed for starting the registration of a sound corresponding to a sub address (e.g., the key input in order of #→*→1) is performed in step S2. If no key is operated, the flow returns to step S1 to continue supervision of a hook and keys. 
     If it is detected that the keys required to start registering a sound are operated, a sub address which has been input using keys in step S2 is stored in the memory 34 in step S3. Next, it has been confirmed that the handset 36 is off from the cradle in step S4a. In step S4, the aural input from the handset 36 is converted to a digital data by the CODEC 35, the resultant digital data is registered in the memory 34 in correspondence with the sub address. Any aural source such as a tone producing device well known in the art may be employed. Then the handset 36 is set on the cradle in step S4b, thereby completing a registration process, the flow thereby returning to step S1. 
     FIG. 6 is a flow chart of the process of generating a ringing tone when a terminating call is received. 
     In step S11, it is detected whether or not a terminating call is received. If a terminating call occurs, the flow goes to step S12 where a sub address is discriminated from a sub address field in a terminating call signal and sound information registered in the memories 34 is retrieved by the MPU 31. Subsequently, in step S13, the aural information retrieved in step S12 among the aural information registered in step S4 in the process shown in FIG. 5 is delivered to the CODEC 35, and a ringing tone is then produced from the speaker 37. Next, it is determined whether or not the hook is on in step S14. The process returns to step S13 to continue producing a ringing tone from the speaker so long as it is determined that the hook is on. Once the hook becomes off, the ringing tone stops, completing a normal connection operation. 
     In the present embodiment, the present invention is applied to a telephone set. However, it can also be applied to any of communication terminal apparatuses other than the telephone set. 
     As will be understood from the foregoing description, in the case where one telephone set is operated in a household or the like in the system where a sub address can be affixed to one subscriber number, as in the ISDN, and where a plurality of terminals are accommodated on one subscriber line, since various ringing tones can be set in the memory corresponding to the number of sub addresses, a call receiver corresponding to a ringing tone can be made ready for receiving a call. This can eliminate an overhead needed for exchanging a telephone speaker which occurs in a charging state, reducing the communication cost. 
     While but one embodiment of the present invention has been described, it will be apparent to those skilled in the art that various modifications and variations may be made therein without departing from the spirit and scope of the invention as claimed.