The complaint was filed by four smartphone owners. The names of the companies involved in the lawsuit include Apple, Carrier IQ, AT&T, Sprint, T-Mobile, HTC, Samsung and Motorola. They have all admitted that their smartphones include Carrier IQ software.

The carriers are claiming that the software is being used only for network diagnostics purposes while the smartphone makers have are saying that they integrated Carrier IQ only because the carriers specifically asked them to do so.

Carrier IQ, based in Mountain View, California, develops and sells software designed to help wireless service providers and cell phone makers identify and diagnose service and quality-related problems, such as dropped calls and battery drain. The software can be used to collect data for analyzing service quality, device quality and what Carrier IQ calls mobile customer experience.

The company has been facing a strong controversy after Trevor Eckhart showed last month how the software could be used to conduct highly intrusive tracking and data collection of smartphone users. The researcher, Trevor Eckhart, described how the software is difficult to detect, difficult to remove and programmed to run by default on millions of smartphones without the users' knowledge or consent.

Apple, which plans to issue an update to remove Carrier IQ software from all its iPhones, on Monday declined to comment on the lawsuit citing the ongoing litigation.