Can I use Cat5/Cat6 instead of phone cables

Blue and Blue white are center pair too. If you punch everything down into an RJ 45 jack (ehternet jack) then an RJ 11 (phone jack 2 pair) can plug into an RJ 45 jack and use center 2 pair. Lines up perfectly. Then the line can be used for RJ 45 or RJ 11 purposes. Good Luck!