Cellphone users are increasingly failing to meet installment contract obligations for the devices and are thus damaging their credit ratings, a Tokyo-based credit information firm told The Japan Times Tuesday.

As of February, about 1.55 million people, or 3.4 percent of everyone who purchased cellphones by installment, failed to pay their bills for three months or longer, according to Credit Information Center Corp.

The number is 1.6 times higher compared with some 920,000 people using such contracts, or 2.4 percent, in December 2010, when the law obliged businesses to provide customer credit information to data firms, including CIC.