No, phone wires only use 2 wires. On the RJ45 its pins 4&5 ( the 2
middle pair) as the other poster said. It should be color coded as
white/blue and blue white. We use RJ 45's at work for phones and they
work fine.
Now if you want to be creative, if you think of going to put in a 2
line phone in the future, you need to wire an additional pair to the
jack. In this case it would be pins 3 and 6 ( I believe its color
coded white/green and green white). So now you would have 2 dial tones
on the jack that would work with a 2 line phone if you ever plugged
one in.