I would look at the possibility of using some of the existing wire within the home, as suggested by Ernie Bornn-Gilman on 02/11/04. I just Retro installed a ZR-8630 with the spare 3 conductors in the phone systems wiring, now it did mean that the keypads ended up in odd locations(next to the nightstand, above the counter in the galley, etc. etc.)but it works. If you contact me or any of the other guy's here in Tech Support at Niles, yes we could explain to you how to make the Keypads run on 3 conductors or even a 2 cond sheilded !!