There may be an extra step to put your house number into Google Voice. I had ported my house phone from AT&T to the local cable company (in a bundle) and they didn't play nicely, so I moved it to Sprint, my cell phone company and I had a cell phone for the house for a year. That was when I moved it to Google Voice. I think the house number can be ported, but I'm not 100% certain, and the rules in your area may be different.

What you might want to do is to port your existing house number to a new cell phone, and then port your existing cell number to Google Voice - if that contract is up then it is the arrangement that would be most affordable. Google Voice will forward your old cell number calls to your new cell phone. This would save the step of porting the house to a cell phone and paying a penalty for cancelling the cell contract early (if you deal with a contract).

The point is, line up your ducks - figure out what can move where according to your various services in the area. Right now I have Google Voice answer my house phone and if I don't pick up the call on my cell phone it takes a message. I could also have Google Voice be the voice mail for my cell phone. There are some advantages to that (blocking, etc., and you can do varying messages for different numbers calling in.)

Poke around in the Google Voice Blog.

SRS