Actually; it appears that all of the mobile phone providers are giving customer data to law enforcement agencies without warrants.
Its just that Sprint has come right out and said that they do it. According to a report on "Security and privacy analysis" by Christopher Soghoian, a PhD candidate at Indiana University, the information includes calls made (to whom and when) and calls received, web sites visited, web searches, and the exact GPS location of the phones when these things were done. Soghoian says that, "Sprint Nextel provided law enforcement agencies with its customers' (GPS) location information over 8 million times between September 2008 and October 2009."
Sprint has apparently set up a website for law enforcement agencies where police can find out pretty much anything they want about a cell phone's use just by entering a search for the number, No warrants required!
Soghoian has a tape of a Sprint executive describing the tools that they make available to police, so Sprint is the one out in the open here, but it seems that all of the mobile service providers have been pretty much bullied into this by ... anti-terrorists?
This is nuts; and way not American. Part of the "Patriot Act" mentality that anything is OK for the anti-terrorism cause. Nah. If we say that, then the terrorists have won. Big time.