My phone outlet is on the front wall and my modem and phone is 13' away on a cabinet in another corner. I think I have one 15' cord for the dsl and a 6 & 10 for the phone.
Haven't measured them but they don't have a lot of excess & they are tucked behind the sectional.

Before we got the wireless we had a cable running along the floor & thru the kitchen, hallway and to the far corner of the dining room.
laminate floors so taped cable down & covered it with rugs

Our layout had about a 25' run of cable so you should be fine - we just had to cross the kitchen & hallway which was not ideal.
if you can go behind furniture good deal.