Hi Bettyk1408, welcome to the community! Thank you for posting.
Sorry to hear of these issues with your landline!
When you receive the 'line cord error' is this happening when you pick up the phone?
Would you be able to confirm you have the handset connected via the adapter provided, and into one of the 'TEL' sockets on the back of the hub? For more instructions on this, and some images for reference please see here.
If this is all set up correctly but you are still without a landline service please do let us know and we will send you a PM to confirm a few details and get a technician booked in for you as soon as possible.
All the best.
Molly