PDF of this tutorialTypically, line-test systems consist of test-system controllers (TSCs), remote measurement units (RMUs), and, oftentimes, a voice-response system (VRS). The TSC functions as the management center of the system to analyze line-test results and, together with other data sources, provides call-center receptionists or other users with simple local language statements on fault location. Meanwhile, the RMUs perform line tests in response to a test request from a TSC. It dials the line to be tested using the exchange test access mechanism, tests the line, and then passes the test results back to the TSC for processing. Once test results are recorded and analyzed by the TSC, dispatch recommendations can be sent to a carrier's operations support system (OSS). The VRS allows field personnel to access the system using a standard DTMF telephone test handset and perform line tests or other fault location sequences from the field without contacting staff at a central office or repair center.
Over the years, suppliers of line test systems have added new technology to locate faults in the POTS network more quickly and accurately. Two of the most significant innovations include use of software-intensive, DSP–based measurement systems and expert system-based analysis. These two technologies enable cost reduction through the ability to see faults in a changing network, improve fault segmentation, and provide shorter test time (see Figure 4).
Figure 4. Maintenance-Cost Reduction
However, as the next section will describe, the real value of this technology is only now becoming evident as the traditional voice-centric network carries more and more data.
