My phone displaying "No Line" for weeks.

My phone has been displaying "No Line" for a while. Weeks. (I don't use it very often). I don't think there's an interruption in service, I think it's not connected properly. I have both green lights steady on the modem. I have an ethernet from the PC to the modem, a cable from the modem to the cable jack, and a phone jack from the phone to the modem. and all are plugged in. No issues with wi-fi, PC, TV, etc. Just no phone. No dial tone.