I have gotten a line in use signal when there is a break in my phone wiring. Thus the first step is to determine what has failed - the phone base, handset, the cord, the jack, household wiring or outside line.
I prefer to use an old corded phone (no power brick around or other basic failure issues) with a different phone wire for diagnostics of the wiring. First plug in the spare phone at the jack where the Panasonic phone is connected. Do you get a normal dial tone with this other phone? If not, try another jack. If you still have no dial tone, find the service box where your telephone service comes in. If you are lucky, the terminals in this box will have RJ-11 jacks. In that case, plug in your test phone and check for dial tone. If there is still no dial tone, contact your phone company, they will repair the line for free.
If there is a dial tone at the service box, then it's an interior wiring problem. Check any exposed wiring for breaks. You can remove the faceplate for the telephone jacks to check for loose wires. Most faceplates use either keystones with the wires pushed into the terminal pins (need a punch-down tool to push in a wire - these are available at home improvement stores) or screw-type terminals (loosen the screw, strip the individual conductor and wrap around the screw then retighten). If the bad wire is inside the wall, you may want a professional to find and fix the problem. Your phone company will do this for a fee.
If your test phone had a dial tone at the original jack, then make sure that the base was plugged in and has power. Check if the power transformer is warm or cold. If it is cold, the transformer has failed and the base has no power. The transformer is part number: PQLV207 (output 6.5 V DC, 0.5 A) Try using the new phone cord that you used with the test phone. Make sure that the handset battery is fully charged and the handset is registered to the base. (I've had handsets loose their registration during an extended power outage.) If the battery is more than a year old, replace it. If you have a new battery and the handset battery will not stay charged, the charger may be bad.
If your phone is under warranty and has failed, let Panasonic fix it. Otherwise, you should replace the phone if the phone has failed. These units are not user serviceable.
The manual for the phone is available here:
http://www2.panasonic.com/consumer-electronics/support/Phones-Fax/Telephones/DECT-6-0-Phones/model.KX-TG1033S .
I hope this helps.
Cindy Wells
(who has had the Line In Use message at the following times: road crew dug up phone line, DSL filter failed, rodents chewed on underground incoming wires. All of the above were fixed by a phone company technician. My test phone gives me fast busy signal or no sound at all since it doesn't have a line in use signal.)
