A major U.S. carrier contacted Kevin Burden to ask if he had noticed anything strange in the BYOD market lately.

As a matter of fact Burden, director of mobility at Strategy Analytics, had picked up on a peculiar anomaly. Although BYOD was still rapidly growing, the number of corporate-liable device purchases was going up as well. In the third quarter of 2013, 35 percent of sales of smartphones used for business were corporate-liable, compared with 32 percent in the same quarter a year prior and 31 percent in the first quarter of 2013.

The report estimates that a total of 73 million smartphones were purchased during the third quarter by business users or by businesses for their employees, marking a 34 percent increase in total volumes from a year earlier.

The possible shift in momentum comes after 2012, which Burden called the year for BYOD.

“It wasn’t like BYOD wasn’t happening before 2012, but when 2012 hit, BYOD seemed to be a buzzword and every company was getting in on it,” Burden said.

Burden said that surge carried over into 2013 but toward the end of the year, as Strategy Analytics tracked BYOD sales through operators and distributers, a noticeable uptick in corporate-liable smartphone purchases emerged. That conflicted with the firm’s prediction that corporate-liable purchasing would slowly slide down to a new sustainable number.

So when the call came from a carrier that confirmed the unusual bump in corporate-liable device sales, Strategy Analytics started putting together possible explanations for the phenomenon.

Burden said one possible reason is that corporations may have held off on corporate purchasing in order to see how the BYOD trend would play out, and now for various reasons, have begun to pick up where they left off.

Another possible reason Burden explained was something that showed up in his firm’s user surveys that suggests business users were less enthusiastic about BYOD now that they had it.

“Now we’re all waking up and going, ‘What did I sign up for? This is my device, my plan and the company’s getting all this additional productivity out of me, I have to be on call all the time, I can’t hide any longer. What did I get out of this? I get to use my own device? Wait a second,’” Burden said.

Burden said revolt by the users may be wording it too strongly but it’s close to what he’s seen with many major tech companies that are rolling back their BYOD initiatives. But in some cases where users pulled back their devices from BYOD programs, their companies simply filled in a corporate-liable device in order to maintain the same levels of productivity and access.

But Burden confirmed one reason he knows for sure that affecting BYOD’s growth is the relatively slow adoption in Western Europe. He attributed this to European carriers’ very separate billing systems for corporate and consumers, causing some concern that BYOD could cause subscriber migration away from corporate accounts, a very predictable source of revenue. The absence of device subsidies in Europe makes it much easier for consumers to jump from carrier to carrier in search of the best value.

In turn, that makes it difficult for companies in other parts of the globe to rollout worldwide BYOD initiatives when they can’t break into Western Europe. Burden is confident that European carriers will eventually merge their billing systems, but in the meantime, it could be holding back multi-national companies.

Looking ahead, Strategy Analytics expects that BYOD will continue to grow but the current rethinking of corporate-liable devices that’s going on could keep those sales increasing as well. Burden said that Strategy Analytics at the end of this month will be putting a survey into the field to hopefully shed some light on the subject.

If the BYOD buzz is really starting to wear off, then it will be enlightening to see what business users think of the practice now. But Burden is confident in the numbers and has confirmed within the industry that something strange is happening in the world of enterprise purchasing.