Newly released research claims that almost half of all mobile phone text messages received in the U.S. are now spam, up from 18 percent just a year ago.

According to mobile firm Wireless Services Corporation, the increased amount of unsolicited SMS messages is attributed to the growing sophistication of spammers worldwide.

"Everyone hates spam, whether it lands in your e-mail inbox or mobile phone," said Rich Begert, president and chief executive at Wireless Services Corporation. It is also costly to US consumers who are billed for the unwanted messages, he added. Spam tricks include scams to trick users into making expensive calls and worms that change device settings and attack other phones.

FCC has listed sites that send spam, and wants them to stop sending spam in 30 days

FCC Lists Sites That Send Cell Phone Spam

and the condition in Korea is worse

Serious SMS Spam in Korea