BOSTON, Mass. – Credit unions who have abandoned the idea of wireless Internet banking because of low adoption rates might not want to let the dust gather too thick on those plans. A new survey by the Yankee Group shows that 12% of young adults in the United States are "totally wireless." Nearly half of the 18- to 24-year-olds surveyed have "significantly replaced" landline phone use with wireless, and 28% plan to completely sever the tie over the next five years. That contrasts with less than 4% of adult respondents over the age of 24 who have abandoned their corded phones, the nationwide survey showed. "The mobile phone has become the essential means of communications, making the landline phone a supplemental and increasingly non-essential item, particularly among young adults and college students who are often not home and who frequently change address," says Linda Barrabee, a senior analyst with the Boston-based Yankee Group research and advisory firm. "Young adults are leading this movement because they seek to stay connected and are more open to changing traditional communications habits," Barrabee says.