To be clear, under long-haul interswitching, the agency is provided with considerable discretion to set the rate. You are correct that it is not a prescriptively pro-rated rate. The agency is given a number of factors to consider in setting the rate, which include the distance as well as other factors, including, for example, the operational requirements of the shipper.
However, it is important to note as well that the rate set is a blended rate. For the first 30 kilometres, it is a cost-based regulated interswitch rate with the balance set by the agency under the approach I just outlined.