For a point to point configuration,with only dial up internet, the best way will be to get two Aplio phones. They are sold on e-bay all the time for around $50 to $70 dollars each.
You start making a normal call, you will pay for the first minute. Once you are on the line, one of the two of you press the big Aplio buttom on the box. The Aplio boxes will drop the normal (and expensive) PSTN call, and “dial” one to each other trought the internet. phone rings and voila, you could talk for hours for what the local internet cost on both ends.
If you need any more info on these Aplios, post on this forum. I have about 12 of them on diferent places and working like champs.