電話電圧検出 - MicroScanner2

Figure 1 below shows that telephone voltage is detected on pair 4, 5.

Length is not shown because the voltage interferes with length measurements.

Figure 1 Telephone Voltages Detected

Warning
The tester is not intended to be connected to active telephone inputs, systems, or equipment, including ISDN devices. Prolonged exposure to the voltages applied by these interfaces may damage the tester.