A methodology for optimizing the access charges paid by a long distance carrier involves the use of a "sizing" operation to determine the optimal balance between direct trunks and access tandems (on a per LATA basis) so as to provide minimal access charges. Once the sizing has been completed, a mixed integer program is used to find the optimal MUX assignments for each LATA. The sizing operation is then re-visited, based on the MUX assignments, to determine if adjustments are required to reduce costs. Any changes in the sizing are then reviewed in the MUX assignment mixed integer program. The end result is a definition of the quantity of direct trunks, access tandem trunks and overflow minutes-of-use charges for each end office, as well as the number of high capacity facilities required for each MUX.