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If they think they do, then an interconnection is set up between X and Y. However, if one party feels that they do NOT derive equal value by interconnecting with the other, than that party usually balks.

This doesn't make any sense at all. Why should X care how much value Y gets out of the deal at all?! This is like saying that Burger King should charge hungrier people more for a Whopper.

It is called price descrimination and it does happen, not at burger king though. For example, those who arrive at certail site via Overture referals end up paying more for goods, compared to those who come from comparsion sites. Alex