ISDN terminal adapter for access from analog signal equipment of four-wire full duplex type to ISDN

A terminal adapter for use in access from an analog signal equipment to ISDN (Integrated Services Digital Network), said analog signal equipment having a first and a second port for transmitting an outgoing analog signal and for receiving an incoming analog signal, respectively, and to be connected to a first and a second analog public telephone line, respectively, so as to use said first and said second analog public telephone lines as a transmitting line and a receiving line, respectively, and said ISDN including an ISDN subscriber's line to be connected to said terminal adapter, said ISDN subscriber's line transmitting a TDM (Time Division Multiplex) signal which comprises first and second communication information channels for conveying communication information and a control channel for conveying a control signal for data link establishment and call control, said terminal adapter comprising:

• input circuit means to be connected to said first port for receiving said outgoing analog signal as a received analog signal;
• analog-digital converting means coupled to said input circuit means for converting said received analog signal to an outgoing digital signal;
• interface circuit means to be connected to said ISDN subscriber's line for transmitting an outgoing TDM signal to and receiving an incoming TDM signal from said ISDN subscriber's line, said interface circuit means coupled to said analog-digital converting means for delivering said outgoing digital signal into a particular one of said first and said second communication information channels of said outgoing TDM signal, said interface circuit means deriving, as an incoming digital signal, a signal of the particular communication channel of the incoming TDM signal;
• digital-analog converting means coupled to said interface circuit means for converting said incoming digital signal into a converted analog signal;
• and
• output circuit means to be connected to said second port of said analog signal equipment and coupled to said digital-analog converting means for delivering said converted analog signal as said incoming analog signal to said second port of said analog signal equipment.