Least Cost Routing is the process of selecting and routing call traffic to the lowest cost destination for each call. This process ranks each available route from lowest to highest cost in real time (using either LRN, or dialed number), then attempts to connect the call starting with the lowest cost, failing over down the line until either the call connects or all available options have been exhausted. Profit protection can also be calculated during this process and may stop calls from routing to destinations based on the profitability or lack thereof. The purpose of Least Cost Routing is to ensure calls are profitable, and to execute at the lowest possible cost for each call attempt. It also gives your network the opportunity to complete a call that one provider may have failed, by route advancing.
In this example, the green rates are carriers that will be used as routing options in the order of lowest to highest rate, whereas the red carrier rates will not be routed to due to profit protection. The profit protection % can be set to any numeric value, even a negative one if desired.