How do you fix Panasonic KX-TGD320 handsets that say Check phone line?

Follow these steps

1. 1

   Power-cycle the base and handsets

   Unplug the base unit power adapter, turn all handsets off, wait 30 seconds, plug the base back in, then turn handsets on and wait for them to link.

   You should see: Handsets resync to the base and errors may clear.

2. 2

   Reseat the wall phone cord

   Confirm a working wall line cord is firmly in the base LINE jack—not a wrong port—and test dial tone from the working handset.

   You should see: Dial tone is present and Check phone line may clear on other handsets.

3. 3

   Clean cradle contacts for the weak handset

   Wipe metal charge contacts on the cradle-only handset and cradle with a dry cloth, charge 30 minutes, then retest away from the cradle.

   You should see: The handset stays on and works untethered, or still fails.

4. 4

   Re-register problem handsets

   Follow the KX-TGD320 manual to register/deregister handsets to the base for units that still error while one handset works.

   You should see: Each handset shows a normal link to the base without Check phone line.