Back when the Bell system had a near-monopoly on telephone service in the United States, just about every call -- whether across town or across the country -- was handled entirely by Bell networks. In the 21st century, a single call can end up being carried across multiple networks. Telecommunications companies sort out the costs of carrying such traffic with carrier access billing systems.
A "Simple" Phone Call
Companies that provide voice and data services are referred to in the telecom industry as "carriers." A phone call may start on one carrier's network, end on a different carrier's network and cross several networks in between. Every call takes up a little bit of bandwidth on the networks -- and carriers are in the business of selling bandwidth, not giving it away for free.
Carrier Access Billing
Carrier access billing is the process of determining which other carriers have gained access to a particular carrier's network, how much bandwidth they used, and how much they owe for that usage. Some carriers handle their own access billing, and an array of companies offer specialized billing services to smaller carriers. And accurate billing is critical. According to ATS Inc., a billing contractor based in West Virginia, carrier access billing can be responsible for as much as 70 percent of a local phone carrier's revenue.