The University of California has joined more than 40 California government entities suing several wireless service providers for allegedly violating their contracts and overcharging government customers by more than $100 million.

The suit alleges that AT&T, Sprint, T-Mobile and Verizon have failed to inform the government entities about which rate plans would be the most cost-effective — something they are contractually obligated to do, said UC Office of the President spokesperson Rebecca Trounson in an email.

A whistleblower originally filed the suit in 2012 at the Sacramento County Superior Court on behalf of the government plaintiffs, according to a court document.

The government plaintiffs allege that by failing to periodically inform them about which rate plans would cost the least, the companies have caused the plaintiffs to sustain at least $500 million in damages.

An AT&T representative declined to comment, and Verizon, Sprint and T-Mobile representatives could not immediately be reached for comment.

Contact Maxwell Jenkins-Goetz at [email protected].