If it's the phone line connected between the Sky box and your phone socket that you're concerned about, any phone line extension will do the job.
---------- Post added at 13:40 ---------- Previous post was at 13:37 ----------
It looks like you have one of these in use already, all you need is a longer one, or else add another one into the cable run that's already there.
http://www.maplin.co.uk/5m-telephone...ual-outlet-921