Need a land line in basement home office

Does a land line phone have to be directly connected to the router in my house?  My router is upstairs next to my primary TV, however I need a desk phone in my basement. 

Without putting a phone at the router and placing a remote/secondary portable phone in my basement, how can I get a desk phone in my basement home office with my router upstairs?

*note: I have horrible reception at home & "Wifi Calling" drops my calls after about 2-3min due to a "known Apple iPhone issue".