| 摘要 |
PURPOSE:To shorten a recovery time by standardizing connection patterns of an automatic switchboard by making a call-back connection when a subscriber who has performed call-back connection operation to a trunk line which is in the holding state in the call-back connection responds again to the trunk line. CONSTITUTION:When subscriber EXTA is to respond again to a held trunk line, the route of subscriber EXTA, line link frame LF and call signal trunk RGT is formed with subscriber EXTA in the off-hook state, and the trunk-line return connection pattern shows a call-back connection. When a ring-back tone is sent from trunk RGT to subscriber EXTA and subscriber EXTA answers, the route of EXTA, LF, trunk line tunk COT, and the trunk line is formed. When subscriber EXTA in the off-hook state is connected to trunk RGT, the same route with the on- hook state is formed. Thus, the connection patterns are standardized and the recovery time is shortened. |
