What might indicate that a telephone line has a grounding issue?

A persistent humming or buzzing noise on a telephone line is a strong indicator of a grounding issue. This type of interference often results from electrical interference that occurs when there is inadequate grounding. Proper grounding provides a path for stray electrical currents to be safely dissipated, and when this is disrupted, it can introduce noise into the line.

The presence of consistent buzzing or humming may be a direct consequence of electrical equipment using the same circuit or improperly grounded equipment nearby, which creates a loop that affects the audio clarity. This type of noise is typically audible during a call and can interfere with communication, indicating the electrical and grounding problems that might need to be addressed.

While the other choices can signal various issues with the telephone line, they do not specifically point to grounding problems as clearly as the persistent humming or buzzing sound does.