Sprint Corp and the U.S. government said on Monday they will face off in court over how much money law enforcement agencies owe the wireless provider for help the company was required to give investigators who wanted to tap phone calls. The Obama administration filed a suit in U.S. District Court in San Francisco on Monday, alleging that Sprint overcharged the government $21 million for expenses it incurred while complying with court-ordered wiretaps and other surveillance help. Sprint said it plans to defend the matter vigorously. Telecommunications companies, including Sprint, are routinely asked to assist with investigations by helping facilitate phone surveillance such as wiretaps or so-called pen registers, which record data about phone calls, though not their content. They are allowed to request reimbursements for related reasonable expenses. In the case, San Francisco U.S. Attorney Melinda Haag alleged that Sprint knowingly submitted false claims to the FBI, Drug Enforcement Administration, Marshals Service and other law enforcement agencies from January 1, 2007 to July 31, 2010, inflating costs by about 58 percent.