Now, I have a question: Why do people think that they need to run CAT5 cable for voice? That is the functional equivalent of running 8/3 Romex for a bathroom fan. Talk about overkill and wasted money. Voice (phone lines) arrive to the premises via "category nothing" cable that runs for miles and miles. Using CAT5 or better for the last 100 feet isn't going to do anything to improve the signal quality. It will certainly empty wallets a bit faster though.
Running cat 5 for that last 100 feet makes sense in future possibilities. It is pretty hard to upgrade premis wiring after the drywall is on. Sure if all you ever carry is simple voice then cat 5 is way over the top. If your telco starts adding TV or Video or Internet as Telus is doing here then installing cat 5 can have a payoff for the customer. Our Telco specs cat 3 as a minimum and that beats Z station wire. The cost of cat 5 over cat 3 is around 3 to 7 cents a meter. On a house that is not that much more.
