The US telco’s practice of refusing to update versions of Android has been dubbed a “deceptive” business practice in a US court. The American Civil Liberties Union filed a federal complaint saying that telcos should keep the software on tens of millions of Android smartphones updated. The complaint said that the dodgy practice means that phones are vulnerable to hackers.

Only one in four Android phones worldwide has the latest generation of the operating system, called Jelly Bean, according to statistics kept by Google, and more than 45 percent run on software first released more than two years ago. Older versions sometimes receive security patches provided by Google, though the process of delivering these to consumers is inconsistent across the dozens of different Android smartphones made by several major manufacturers.

The ACLU filed the complaint with the Federal Trade Commission, which has taken a lead role in overseeing the burgeoning technology industry and reached a settlement with smartphone maker HTC America in February over charges that it had failed to secure user information on smartphones.

The complaint names and shames Verizon Wireless, AT&T, Sprint Nextel and T-Mobile USA.