What should the meter read when measuring a POTA with the phone off the hook?

What should the meter read when measuring a POTA with the phone off the hook?

• A. 7-9VDC
• B. 0V
• C. 12V
• D. 120V AC

Answer: (A)

When the phone/line is off the hook in this POTA setup, the circuit is closed and current flows through the line supervision network. That causes a small DC bias to appear across the line, not a full supply or an AC waveform. The typical reading you’d expect is a modest DC level around 7–9 volts. This shows the line is active and loaded in the off-hook state. A reading of 0V would indicate no load or a shorted condition, 12V would be higher than the normal loop bias for this test, and 120V AC isn’t used on these low-voltage telephone lines.

When the phone/line is off the hook in this POTA setup, the circuit is closed and current flows through the line supervision network. That causes a small DC bias to appear across the line, not a full supply or an AC waveform. The typical reading you’d expect is a modest DC level around 7–9 volts. This shows the line is active and loaded in the off-hook state. A reading of 0V would indicate no load or a shorted condition, 12V would be higher than the normal loop bias for this test, and 120V AC isn’t used on these low-voltage telephone lines.