It's not completely illegal for police departments to obtain your cellphone records from wireless carriers without a warrant. So, they do it. A lot.
Wireless carriers seem happy to comply, perhaps because they get to charge lots of money every time someone asks for something, and the ACLU has found out how much money this is.
If you're a law enforcement agency of some sort, you have a nice fat à la carte menu of wiretapping, data harvesting, and electronic tracking items to choose from. Here are the going rates as of 2009, broken down by service and then by carrier:
Wiretapping, per target
- AT&T: $325 activation fee, $15 per day for data and audio
- Verizon: $500 flat fee
- Sprint: $400 per market area, $10 per day, $2,000 monthly cap
- T-Mobile: $50 administrative fee, $700 per month
Voicemail and text message access, per target
- AT&T: $150 for voicemail
- Verizon: $50 for text messages
- Sprint: $120 for pictures or video, $60 for email, $60 for voicemail, $30 for text messages
Location information and real-time tracking, per target
- AT&T: $100 activation fee, $25 per day
- Sprint: $30 per month
- T-Mobile: $100 per day
Tower dumps (which provide a list of all numbers accessing a cell tower)
- AT&T: $75 per tower per hour, two hour minimum, rounded up
- Verizon: $30 to $60 per tower per hour
- Sprint: $50 per tower
- T-Mobile: $150 per tower per hour
There are two things that we should probably mention in the carriers' defense: one is that in emergency situations, they always provide all of this information for free. And two, most of them claim that they're not actually making any money, just recouping the cost of getting the information out of their system. However, the fees are so varied that you have to wonder if that's really true, and this is potentially a huge cash cow (especially for T-Mobile, by the looks of it).