You can run a phone line off an existing jack to another jack. Just match up the colors on the wire. If you are not willing to challenge those creepy-crawlies that inhabit small crawl spaces (and I don't blame you there!), you might consider running the phone wire behind the baseboard. If you remove the baseboard, you can take the wire from one room to another simply by drilling a hole through the bottom of the wall, and then replacing the baseboard over the whole (do make sure to remove the baseboard on both sides of the wall so you don't end up with a hole drilled through one of them.) Sometimes, if you are VERY careful, you can simply push the phone wire underneath the baseboard (especially if you have carpet) and run it around the room that way, but do be very careful because phone wire is delicate and it doesn't take much to break the circuit. Obviously, if you go to all this trouble to run the wire and the circuit gets broken, the phone won't work in the new jack, and you will not be a happy camper.