How and what data does the FBI collect from telecommunications companies?

The article on Vice explores how the FBI accesses phone data from the three largest American carriers: AT&T, T-Mobile, and Verizon. It reveals that the agency employs various techniques to obtain information about users' locations, calls, and text messages. Many of these practices are not publicly known, and customers are rarely informed that their data might be shared. There's also controversy about how much data is collected and stored by these carriers and how long that data is retained. Critics point out that such actions could infringe on citizens' privacy and lead to potential abuses by government agencies.