Even though most companies would list the phone bill as one of their top expenses, few take the time to have someone look over the bill for errors. A study found that 80 percent of U.S. businesses have errors on their phone bills that are never found or reported.

The problem comes from the long-standing system phone companies use to track their services and billing. The system is split into two sections: The section that keeps track of what services a customer has, and the section that bills the customers. “The process itself is inherently faulty,” says professional Frank Stoczko. “It’s quite often the case that there’s faulty entry between the two systems, which results in faulty billing.” Stoczko says a customer may get a feature (such as caller ID) and then cancel it, but the phone company may only cancel it from the service section of the billing system. Then, customers are being charged for a service they no longer have.

According to Stoczko, billing errors have been occurring since the dawn of telecommunications, and certain phone providers can be almost relied on to make trademark mistakes. “As soon as I see who the telephone company [on the bill] is, I look for those specific things, because, invariably, those kinds of errors are repetitive; they happen quite often,” he said.

Without actually stating that phone companies make these erroneous charges on purpose, Stoczko does point out that it is in the phone companies’ interest to allow these mistakes to be made. ” [Telecoms] will just let mistakes go and wait for clients to come back and ask for a refund for that money,” he said. “They will pay them that money, while the other customers’ [overcharges] will just be pocketed.”

However, some of the phone companies overcharge through legitimate services that are not really necessary. One such service is an insurance premium for in-house wiring that some companies charge a flat fee for (maybe $4 or $5 a month). Stoczko says it is a good idea to get rid of services like this, because it is a service that probably won’t ever see use. “[Consumers] pay for the insurance for the entire time they have telephone service