Japanese women are so fond of their phones, they even use them in the shower, say manufacturers. This makes waterproofing a must -- also good against rainstorms and accidents while texting on the toilet.
Panasonic and Fujitsu are touting their waterproof and dust-proof phones as they seek to charm the overseas market at the world's biggest mobile phone show in Barcelona this week.
"In Japan, you can't sell a phone if it's not waterproof. About 90 to 95 percent of all phones sold now are already waterproof," Panasonic executive Taro Itakura told AFP at the Mobile World Congress.
"Why? This is very unique -- young Japanese women prefer to use their cellphones even when taking their showers," Itakura said.
"Cellphones have become 'must products'."
Panasonic is looking to re-enter the European market after pulling out in 2005 to concentrate on its domestic sales.
"The reason we decided to come back is that there have been a lot of changes in this industry with the introduction of the smartphone," which has become a "global product," he said.
"In order to survive in this industry as a manufacturer, we, Panasonic, have to be strong in terms of global competition."
It is not known whether Europeans share the Japanese fondness for phoning in the shower, but Itakura hopes they will consider the benefits for chatting in the rain.
A third of damages to phones comes from water, said Florian Sohn, a Panasonic marketing specialist for Europe.
"You may drop the phone in the bathroom, or bring it close to water when you wash your hands or it may fall inside toilets," he said.
Dust-proofing meanwhile can appeal to customers such as construction workers, he added.
Fujitsu, which has a fifth of the Japanese smartphone and tablet markets, also sets great store by waterproofing.
"The mobile phone is with us 24 hours a day. It accompanies us to the bathroom, to the shower, or under the rain. So it is a necessity for the phone to be robust," Nobuo Ohtani, Fujitsu corporate senior vice president, told AFP.
While better known abroad for their laptops, the Japanese giant is now also trying to sell phones to Western markets.
In Barcelona, it showcased its range of phones already available in Japan, as well as a new "quad-core" phone with extra processing power.
Besides being waterproof, the phone also appeared crack-resistant when hammered repeatedly with a falling steel ball.
Ohtani said Fujitsu's smartphones will also offer "human-centric technology" that makes the devices easier to view or hear, a particular advantage for the elderly user.
This technology includes sensors that raise or lower the volume of a call, or even slow down speech if the caller is speaking too quickly.
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