| 摘要 |
PURPOSE:To record data on an incomplete call economically, by deciding that a call is an incomplete call through a call recording device on the basis of the time length of a pseudo call signal, and then performing prescribed recording regarding it. CONSTITUTION:To the signal line from a call connecting trunk ICT to a call recording device OCM, a pseudo answer signal shorter than a prescribed time is sent out when an optional call is disregarded before a called subscriber answers. The device OCM decides on an incomplete call from the continuation time of said pseudo answer signal. The completion time is regarded as abandoned time and data on that is recorded through a magnetic tape device MTS. Thus, even the incomplete call is recorded without increasing the number of signals lines between many trunks ICT and the device OCM in a telephone exchange. Therefore, call recording of the telephone exchange is performed economically and accurately. |
