On a tour for journalists attending the International CTIA conference yesterday, Nokia engineers demonstrated sophisticated tests on many of its devices, including smartphones and more traditional cell phones.

The engineers dropped, twisted, steamed, dunked, scraped, vibrated and generally tried to destroy the phones to show the processes that Nokia uses in 10 device testing labs around the world.

In one test, a small piece of plastic used for what is termed a 'window' on a phone display was propped up on a stand with pressure precisely applied from a metal bar above. Nearby computers measured and recorded what pressure was applied, bending the window to the point of breakage, which sounded like a quick 'pop'.

The precisely applied pressure on the window is like "an elephant wearing a stiletto standing on a phone," said Mike Myers, a mechanical test engineer at the lab.

Other tests involved robots that continuously pushed phone buttons, opened slider phones or scraped surfaces to find out when painted on numbers started to fade.

There were also a variety of drop tests: A pendulum swung around to bash a Nokia 6650 phone, while another boxlike device rolled phones for hours. In a more sophisticated drop test, a robot arm lifted a phone to a height of about 7 feet, dropping it into a chamber where it landed on a concrete pad. A high speed camera recorded the drop to record how the phone hit the pad for clues to what could cause breakage.

"We test things to failure," Myers said, noting that the button pressing robots will speed up the use of a phone by an average user, applying hundreds of thousands of button pushes over five days.

Nokia has developed many of its own tests atop a group of international standards used for testing phones and small electronic devices. One of the more unusual tests involved pieces of cloth pockets that rotated in a drum, in which the engineers placed a phone with keys and pennies to simulate what might be happening in a man's trouser pockets while carrying a phone.

Chris Rubie, manager of the environmental testing lab, showed an enclosed tray that was made to vibrate violently, with dust thrown in with cell phones that danced like jumping beans.

"What happens for most of us is that we come home and pull the phone out of our pockets and toss it on the table," Rubie said. "So we're interested in seeing how dust and cotton from clothing gets into the seams of a phone."

Nokia also simulates more commonly reported problems, including a user dropping a phone in a toilet or making a call in the rain, but the testing devices employed don't resemble bathroom fixtures. One device applies heat and steam to simulate jungle swelter at 95% humidity. Another simulates a downpour while other tests chill and bake phones from -40°C to 120°C, Rubie said.

A separate failure analysis lab is designed to look at problems in phones at the microscopic level, making use of equipment including a scanning electron microscope that can detect cracks in solder joints as tiny as 300 nanometers. A single piece of paper would be about 250 times as thick as a crack of that size, said Mike Wellborn, manager of the failure analysis lab.

"Sometimes a failure is too small to see," Wellborn said.

Wellborn showed an actual case he investigated over several days, where testing engineers had noticed the repeated failure of a hinge on a flip phone under development. Microscopic 3D analysis was able to show that air packets inside the molded magnesium hinge area were weakening the hinge. Nokia passed on this information to its supplier for correction.

Nokia has long prided itself on high quality phones, and recently began a campaign to show off its hardware resilience, as well as its software prowess, to wireless carriers that sell to buyers who are less familiar with the products.

Ira Framer, product portfolio manager for Nokia North America, remarked that Nokia's goal is to be "No. 1 in the U.S."

Rubie said the testing labs help to make Nokia phones "robust" for most consumer usage. However, he said he was not authorised to say how many years of average use any certain phone model can expect to last. Obviously, some users will present extremes that go beyond the limits of Nokia's testing, "like the farmer who drops his cell phone off the tractor onto a dusty field and jumps off the tractor onto it," he said.

But Rubie said there is a complex analysis in developing phones, involving the costs of materials and production, but also what carriers and, ultimately, consumers are willing to spend. The process involves tradeoffs between quality and price, he said.

One testing manager, who works for a major mobile network and was not authorised to speak to the press, said phones can frequently last four or five years under average use, but so many innovations have come to phones in recent years that users are eager to move to a different model more frequently, often as soon as their two year contract expires or when a battery fails.

As a result of innovations in web browsing and interfaces, carriers are constantly updating the supply of phones they offer, picking devices from different manufacturers, the testing manager said. One way faulty products are filtered out is when a carrier sees too many returns of devices from a specific manufacturer.

"The next time that manufacturer comes to us and says we have a hot new phone, they might go to the back of line behind the others," they said.