Zyxel EX5501-B0

I bought a ZYxel router modelEX5501 BO. The seller told me that it was an open router. When the router arrived at my address, I determined that it was a router for the Telia operator, and I could not access it via IP address (192,168 .01) .How did the seller cheat me and I can't get to it, is there a way to put open firmware in it or how could I use it as an AP depending on the situation? 
. Please for any help.
Thank you.