Sprint filed the lawsuit at the District Court of Kansas on Monday May 22. It claims that IBM failed to make productivity improvements, and owes it at least $6.4m in uncompleted work.

The five-year application-development and maintenance contract was first signed in September 2003, and was extended in July 2004, but the Sprint CIO who organized the deals, Michael Stout, left the company last year.

Although the amount of money involved in the lawsuit is small, it signals a potential breakdown in the relationship between the two companies, which also have a multi-billion-dollar customer-service agreement. However, a Sprint spokesperson told Computer Business Review that despite the lawsuit, the companies are continuing to work harmoniously together.

A number of major outsourcing deals have resulted in legal action over the last two years, including a $2bn deal between CSC and Sears, which the retailer is attempting to have canceled.