| 摘要 |
PURPOSE:To increase the service to telephone subscribers, by dialing the number predetermined from the extension through the use of call back trunk to hold the trunk line. CONSTITUTION:When an extension EXT desires the holding of trunk line during the communication with trunk line via a switch frame LF and trunk line trunk COT, hooking or dialing is made at the extension EXT side. Thus, the trunk COT starts the marker MKR. Further, the marker MKR is connected to the trunk via a vacant call back trunk CBT and a call back link CBL. Next, the extension EXT dials the specific number as the trunk line hold number HD. Further, when the extension EXT desires the restart of communication with the trunk line, if the handset of the extension EXT is hooked off, the marker MKR connects the trunk CBT and the link CBL to the trunk COT. Thus, the trunk line is held to increase the service to telephone subscribers. |
