| 摘要 |
PROBLEM TO BE SOLVED: To provide a transmission line obstacle detection system, capable of reducing equipment expenses by using JJ20-11 of a transmission line and also utilizing a Dp channel. SOLUTION: In a network configuration in which a Dp channel common line signal system is utilized, a link establishment sequence as link establishment condition is divided at a network side and a user side and a line is established on by receiving both messages of 'DL(download)-setting-display' and 'DL- setting-completion'. |
