All voice network operators are continually looking for ways to cut the cost of delivering outgoing long distance calls. The best way to do this is to use 2 or more Inter-Exchange Carriers (IEC, in FCC-speak) or what you and I might call “long distance service providers,” and cherry pick the cheaper provider for each dialed destination. This approach is called “Least Cost Routing.” Seems simple, right? Well, it’s not, really.
First there is the tyranny of numbers. A Least Cost Routing application typically will use the Local Exchange Routing Guide (LERG) to determine all possible dialed destinations. The LERG defines roughly 450,000 destinations. For each destination you might have a cost proposal from several IEC. We tried evaluating 8 IEC.