How do you measure for voltage on a home telephone line?

To measure voltage on a home telephone line, you'll need a multimeter set to the DC voltage range. Connect the multimeter probes to the two wires of the telephone line, typically the tip (positive) and ring (negative) wires. A properly functioning phone line should show a voltage between 40 to 60 volts when the phone is on-hook (not in use). Always ensure safety by avoiding contact with the wires and using insulated tools.