| 摘要 |
PURPOSE:To respond the additional information at a terminal side after discrimination, by inserting the additional information at the point of time of incoming call for the transmission and reception of signals between terminal exchangers from the incoming call to the response. CONSTITUTION:The information from a terminal is converted to a data bit 12 through a line T of a terminal interface line and the control from the terminal is converted to a signal bit 11 through a line respectively via a line terminator. The information from an exchanger is converted to a data bit 12 through a line R and to a signal bit 22 through a line I respectively via a line terminator. In a terminal of vacancy, the line R is at level 1 and the line I is at off-state. When an incoming call is present from the exchanger to the terminal, an additional information character preceding a suitable number of SYN characters is transmitted on a data bit 21. The characters are transmitted on the line R and a BEL character is continuously transferred while keeping the character synchronism to transmit it on the line R. The terminal side discriminates the additional infromation and responds to it as required. |
