Hardware :: Using Cat 5 Wire For Telephones?

So, I've bought a new house (well, a very old house), and I'm having some work done on it, which includes getting Cat-5 and other comm. wiring installed.

I was thinking of dispensing with phone wiring, since I imagine in 5-10 years phones (cat-3 wiring) will be irrelevant and we'll be on VOIP. Instead, I figured I could get each room wired for 2 or 3 cat-5 (ethernet) jacks. In the meantime, I would use an adapter so I could plug a phone into the ethernet jack. Then at the patch panel in the basement, I'd use the same jack, and wire the phones together.

1) Does that adapter exist? I think it would be an RJ11 to RJ45 adapter.

2) Any problems with this plan? Obviously I'd be careful about which jack is for which, because I imagine that the ring signal wouldn't be so good to send to a computer.