Apple is still ahead of PC competitors Dell and HP in customer satisfaction when it comes to its telephone tech support, but the company’s numbers have been slipping over the last 18 months, according to a new report from Vocallabs.

The research firm said that the number of Apple customers reporting that they were “Very Satisfied” with their phone tech support fell to 54 percent during the last half of 2011. That’s down from 58 percent in the first half of 2011, and well down from the 73 percent of customers who said the same thing in the first half of 2010.

While that’s a precipitous drop, and possibly an area of concern for Apple, it was enough to keep the company ahead of Dell (44 percent) and HP (49 percent). Both of those companies held relatively flat over the last 30 months, as shown in the chart below. Both companies also saw similar drops to Apple’s in the last half of 2011.

Source: Vocallabs
(Click the image for a larger version)

Another figure released by Vocallabs concerned satisfaction with the agent that customers spoke to. Here again, Apple’s numbers slipped over the last 18 months from 82 percent saying they were “Very Satisfied” in the first half of 2010 to 72 percent in the second half of 2011.

In this case, however, Apple is crushing Dell and HP, both of whom received only 52 percent during the same period, and neither of whom has been over 61 percent during the last 30 months. HP’s numbers decreased some nine percentage points in the last half of 2011, almost as much as Apple’s ten percent decline.

Apple is also leading its competitors in overall customer satisfaction. According to Vocallabs, Apple had 56 percent of its customers say they were “Very Satisfied” with Apple. That’s a ten percent decline over the last 18 months, as shown in the chart below, but it’s ahead of Dell’s 47 percent and HP’s 43 percent.

Source: Vocallabs
(Click the image for a larger version)

As shown in the bottom portion of the chart, Apple is crushing its competitors in customer willingness to recommend its products to family and friends. 83 percent of respondents said they would recommend Apple products, while only 68 percent of Dell’s customers said the same thing. 66 percent of HP’s customers said they would recommend that company.

One factor contributing to that could be that only 0.95 percent of Apple’s customers complained about their agent’s ability to speak English, while eight percent of Dell’s customers offered a complaint and more than ten percent of HP’s customers did the same. Both Dell and HP have outsourced much of their tech support to call centers outside the U.S., while Apple has not.

For clues on specific areas where Apple has been experiencing problems, Vocallabs offered the chart below, which shows that tech support resolution and the ease of reaching a support agent both declined from 2010 to 2011. At the same time, complaints about the automated portion of support calls and the wait to get to an agent both increased.

Source: Vocallabs
(Click the image for a larger version)

Vocallabs derives its data by asking people to call a phone number controlled by the firm, rather than calling the above-mentioned companies directly. Those calls are then forwarded to Apple, Dell, HP and whatever other vendors Vocallabs is following, allowing Vocallabs to independently monitor the call’s progress. Customers are then given a follow up phone call after the tech support call is complete in order to ask their opinions about the call.

One bit of contextual information is that Apple’s Mac sales have been growing in leaps and bounds during the last several years, and the December quarter of 2011 alone saw more Macs sold than in all of 2001. That means that Apple has had to drastically expand its support infrastructure to accommodate all those new customers.

Considering the number of people new to the Mac that includes, the real surprise here may be that Apple has been able to maintain tech support satisfaction as high as it has, rather than the decline reported by Vocallabs. That said, this is something the company will have to continue to improve if it wants to maintain its long-standing industry leading edge in customer satisfaction and loyalty.