In the first public accounting of its kind, cellphone carriers reported that they responded to a startling 1.3 million demands for subscriber information last year from law enforcement agencies seeking text messages, caller locations and other information in the course of investigations.
The reports also reveal a sometimes uneasy partnership with law enforcement agencies, with the carriers frequently rejecting demands that they considered legally questionable or unjustified. At least one carrier even referred some inappropriate requests to the F.B.I.
The information represents the first time data have been collected nationally on the frequency of cell surveillance by law enforcement. The volume of the requests reported by the carriers — which most likely involve several million subscribers — surprised even some officials who have closely followed the growth of cell surveillance.