Leased (Dedicated) Line Recovery System under utilized (Action taken)

From Fiscal year 1993 Audit Report

NTT's Leased line Recovery Service under-utilised many transmission circuits, for which the installation cost totaled ¥192 million.


Service Description

  1. Nippon Telegraph and Telephone Corp. (NTT) provides a "Leased Line Service" (LLS) which enables subscribers to rent and exclusively occupy communication lines for transmitting various communication media such as computer and facsimile data, and human voice between the subscriber’s computer center and data terminals. As of 31 March 1994, NTT provided approximately 1,010,000 contracted LLS communication lines nationwide.

  2. Since Fiscal Year 1982, NTT has installed LLS Line Remote Testing System (RTS). This system saves LLS line maintenance manpower by quickly identifying the places where problems and failures occur. The cumulative RTS acquisition cost as of 31 March 1994 amounted to ¥33,800 million. The RTS accommodates LLS Line Remote Testing Machines (RTMs), and the Junction Board Circuit (JB Circuit) of RTMs must be connected to each subscribers line to detect faulty sections in LLS lines quickly and to help resolve the problem. There were 868,944 NTT JB Circuits as of March 31, 1994.

  3. In FY 1992, NTT started to install a digitized Transmission System in its branch offices which performs the same function as RTMs. NTT branch offices connect subscribers' LLS lines either to RTM JB Circuits or to this new system.

Audit Findings

  1. The Board examined RTM JB Circuits occupation rate in 23 NTT branch offices. The audit found that:
  1. JB Circuits which were not connected to subscribers' LLS lines as shown below:
  2. Percentage of unused circuits

    Branch offices

    Less than 30% unused

    7 offices

    30% - 50% unused

    13 offices

    More than 50% unused

    3 offices


    Of these 23 branch offices' 89,906 JB Circuits, only 55,065 circuits were connected to subscribers' LLS lines.

  3. Of these 34,841 unused circuits (86,906 – 55,065), 32,086 circuits were unused even 6 months after they were installed in RTMs;

  4. Of the total 218,042 LLS lines that these 23 branch offices had to connect to RTM JB Circuits, 160,827 lines were still not connected to JB Circuits;

The Board determined that NTT failed to connect 23,000 subscribers lines and leave the same number of JB Circuits unused, taking into account the necessary number of reserve circuits. The cost incurred for these unused circuits amounted to ¥192.00 million.

  1. The Board found that these were because:
  1. NTT branch offices were not active in connecting the subscribers' LLS lines to RTM JB circuits because:
  1. Branch offices did not sufficiently establish and adjust plans for subscriber line connection to RTM JB Circuits or the new system;
  2. NTT headquarters failed to grasp nationwide LLS line connection, and consequently failed to offer appropriate instruction to branch offices.
  1. Based on the Board’s findings, the NTT headquarters in November 1994 issued an administrative circular to branch offices instructing them to:
  1. promote LLS line connection with subscribers' consent;
  2. establish and adjust connection plans to RTM JB Circuits or the new system;
  3. submit LLS line connection reports regularly.



TMB = Transmission Machine Building

RTS = GCS Line Remote Testing System

LCE = Local Call Exchange

TCE = Trunk Call Exchange



Back to Publications Index