It is often said that we live in a "service economy," meaning that a disproportionate amount of the stuff our economy produces is services, as opposed to manufactured goods or agricultural products. In a service economy, most of what people buy is not tangible goods but intangible services: the service of being transported from Point A to Point B, the service of having your money efficiently managed, or the service of having your voice transmitted to someone else on the other side of the country, just to name some examples.
If factories manufacture goods, then call centers manufacture customer service. They take the raw materials (technology and time), add the labor of customer service agents, and produce good (or bad) service.
But where the idea of a factory is over a century old, and manufacturing process and quality control is well understood, call centers have only been around a few decades, and companies are still struggling with the best way to measure the quality of the service delivered.
In many ways, the call center industry is still at the same stage as Henry Ford's Model-T factories: working to maximize the number of calls handled per hour at the lowest possible expense. Quality measurement is still a slippery enough concept that it is too easy to just focus on cost.
But just as car manufacturers discovered in the 1970's that quality matters, some companies are beginning to wake up to the fact that customer service quality matters to customers. Measuring customer service quality isn't as straightforward as making sure the size of a ball-bearing is within manufacturing specifications, but it can be done. Companies like Apple Computer and jetBlue Airlines have learned that they can be profitable even in brutally competitive industries by being the service leader.