Cordless Telephone Bridge

I'm trying to figure out how (or if) I can use an old cordless phone as a tranciever, wiring in an rj11 jack to the phone's reciever to essentially make a cordless phone "bridge" so that I can use my desk phone in an area without phone cabling by plugging it into the cordless phone's reciever. I've tried the phone over power adapters and haven't had great luck with 'em, so I'm trying to think outside the box. Anyone have a suggestion or two?