"LINE IN USE" FLASHING LIGHT ON CONSTANTLY W/NO LINE IN USE
I suggest you make arrangements to have a technician visit my residence to correct the problem. I am wondering if changing to fibre optic may have caused this. My old answering device still indicates "line in use". It does not have a flashing red light. This may have been going on for a long time without my knowledge.
I can be reached during working hours on my cell 941-773-3034. or, at my home phone after 5 PM.
Experience in troubleshooting and performing hardware replacements in PCs, smartphones, basic cell phones,...
Don, are you able to use the phone and make outgoing calls, or receive calls? If you have tried the devices on other phones and they are working it could be the device its currently connected to is not properly functioning, or is still connected on the line without hanging up completely.