| 摘要 |
PURPOSE: An apparatus for sensing an incoming loop using line battery reversal on answer and a method thereof are provided to accurately judge loop status of a receiving part without an erroneous connection. CONSTITUTION: A control device loops on a relay toward a trunk line(S1). The control device controls a dial sender to send a dial(S2). A busy tone and ring back tone sensor checks an input signal for detecting a busy tone or ring back tone(S4). In the case of the busy tone, the control device judges whether a connection is a retrial, so that the control device loops off and retries the dial(S6-S8). If not the retrial, the control device loops off and terminates(S9). In the case of the ring back tone, the control device judges whether the signal is an LBRA(Line Battery Reversal on Answer)(S5). If the LBRA, the control device executes all kinds of control functions and thereafter loops off(S10).
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