Intranet connection both voice and data

We are the process of setting up a intranet with our branches. We want to have both voice and data going across the lines. Two the branches are large enough to require T-1 lines but the other only has two phones and three computers. What would bethe best choice for the line to this branch. I have been told frame relay or switched-56 and can not make the decision which one is best with least cost and work best for both voice and data.