SquareTrade also mined its claim data for Research in Motion's BlackBerry, and found that the company's hardware failed at a 6.3% annual rate, triple that of the iPhone 4 and almost double that of HTC.

All failure rates excluded claims for accidental damage, such as shattered screens caused by dropping a smartphone.

"As long as you're sticking with the iPhone, Motorola and HTC, you'll be fine," said Tseng. "Those are the most reliable smartphones around."

But what grabbed Tseng's attention was the major improvement in reliability since SquareTrade last examined its claim data in November 2008.

Then, BlackBerrys failed at a whopping 11.9% rate in each 12-month span, while 5.6% of Apple's iPhone 3G phones -- its newest at the time -- failed in the same period.