Cellphone carriers answered at least 1.1 million requests from law enforcement agencies seeking information on caller locations, text messages and other data for use in investigations last year, according to the carriers’ reports.

The New York Times reports that most of the requests were for information from a specific customer account, but law enforcement agencies also received information from 9,000 “tower dumps,” in which agencies are granted access to data from all phones connected to a cell site during a specific period of time.

These reports underscore law enforcement agencies’ reliance on wireless phone records.

They were requested by Senator Edward J. Markey (D-Mass.) from seven carriers, including AT&T, Verizon Wireless, Sprint and T-Mobile US. Senator Markey says that he plans to introduce legislation in the coming weeks that would provide stronger privacy protections for consumers, including the requirement of a warrant for police to get cellphone location information from carriers as proof that it would help undercover evidence of a crime, NYT reports.