Image: Customer service worker © Beau Lark, Corbis

A call to a customer service department is, in many cases, enough to spike a customer's blood pressure.

There are long hold times, irritating music or, worse, repeated advertisements. After connecting to a call center, perhaps one staffed by reps with foreign accents, you will probably be rushed into a quick and easy "fix" that may, or may not, solve the problem, since many call centers rate their reps' success by how many customers they handle in a set amount of time.

Why are so many customer calls handled so poorly?

Peter Leppik is the CEO of Vocal Laboratories, also known as Vocalabs, a Minnesota company that digs deep into what some companies do right, and wrong, when it comes to customer-support calls. Rather than cast a broad net, his firm's approach to its National Customer Service Survey -- ongoing research on customer satisfaction with phone-based customer service -- focuses in depth on three vertical markets: computer technical support, mobile phone customer service and major national consumer banks.

What phone support should -- or can -- accomplish varies from industry to industry, sector to sector. For retailers, for example, customers may complain about being routed to a centralized support center. But the alternative, having staff answer phones at each location, distracts staff from being on the floor helping in-person customers.

The computer marketplace

The computer marketplace has its own unique challenges.

"There are a lot of things that can be fully automated," Leppik says. "But with tech support there are actually very few things that can be fully automated."

Apple, year after year, has been lauded by customers and consumer groups for having stellar customer support, and overall Vocalabs' research bears out that reputation.

"In most industries there are one or two companies that really get it," Leppik says. "In terms of tech support, Apple has a reputation that is justified. The statistics we have collected show that they are significantly ahead of their peers."

What Apple has done right, and where others flounder, is in the "strategic decision that they are going to compete on the basis of customer service," Leppik says.

It is a lesson other companies might want to emulate.

"You don't necessarily have to spend a whole lot more money providing a level of service, but what's important is that everybody on that front line understands that what the company does is important," Leppik says. "There are a lot of companies that do not feel like that customer service is important. They send the jobs to India. (For others), they are giving the message to employees that what they are doing is strategically important and the company cares and is watching."

Despite accolades, Apple does occasionally stumble and could be losing its edge as competitors make improvements.

Vocalab's 2011 surveys found that Apple continues to lead Dell and Hewlett-Packard in customer-service quality for phone-based technical support. But customers are reporting more problems with the automated part of their calls.

In telephone interviews immediately following a support call, 58% of Apple customers were "very satisfied" with the experience during the first six months of 2011, compared with 47% of Dell customers and 53% of HP customers. Apple's satisfaction score is down 15 points from a year ago, though, while HP has improved nine points over the past two years.

Customers remain highly satisfied with Apple's support agents, with 77% of customers in the first six months of last year being "very satisfied" with their technician, compared with 56% of Dell customers and 61% of HP customers.

The automated part of the call is a different story, with only 24% of Apple customers being "very satisfied" with that part of the experience, trailing Dell's 36% and HP's 40%. In this survey period, 40% of Apple customers reported a problem with the automated part of the call, nearly double the 21% rate from a year earlier.

"Apple used to be well ahead of the pack in tech support," Leppik said at the time of the study. "Now it would be fair to say that they are merely at the front of the pack. Apple used to lead on nearly every metric for support quality. Now there are several metrics where Apple is tied with its competition, or even trails."

Mobile providers

Leppik cites Sprint as an example of a company that has made customer-service improvements -- and the difficulty a company can have trying to maintain that edge.

"Sprint historically has had very poor customer service," he says. "At the beginning of 2010, they made a decision that they were going to improve their service level, and we saw their numbers go way up."

Sprint made impressive service gains during 2010, moving from the bottom of Vocalabs' rankings in 2009 to being statistically tied for first place in many key metrics.

"They were still kind of mediocre, but compared to where they had been, they were doing a whole lot better," Leppik says. "But then, in 2011, I don't know what their thinking was exactly, but it was very obvious that they had turned their focus on customer service to other things, and the numbers went right back down. That's an example of what happened when customer service is a flavor of the month."

Leppik stresses that he has no firsthand knowledge of Sprint's internal strategy decisions regarding customer support. The company, however, appears to be making the common mistake of treating this aspect of customer service as a "project, not process."

Click here to become a fan of MSN Money on Facebook

"I think a lot of this goes back to the view of customer service as infrastructure," he says. "You build infrastructure, and then it's there and you don't have to keep building it every year. But customer service really is not infrastructure. In a lot of companies it is the only time a customer actually communicates directly with the company. That has far more power on that customer's perception than anything else the company can really do.

"The thing about customer service, as a strategy, is that you can't do it for a short period," he adds. "It is something that can be very powerful, but it takes time to change the overall perception of a company. It takes a lot of repeated positive customer experiences. It takes a lot of time for that word-of-mouth shift. If you are looking at this quarter's financial results, it's not always obvious that the investment is paying off."

In October research, Vocalabs found that AT&T recovered in the quality of customer service, while Sprint continued to lose ground.

More from TheStreet: