Major U.S. cellphone providers received more than $20 million from law enforcement agencies in conjunction with more than 1.1. million user information requests in 2012, according to documents released Monday by Sen. Ed Markey, D-Mass.

Five of the seven companies queried by Markey offered precise or ballpark figures for the revenue they received from law enforcement in 2012.

AT&T said it received $10,298,000, T-Mobile USA said approximately $11 million, Verizon Wireless said less than $5 million, U.S. Cellular said $241,000 and C Spire said $55,000.

Cricket and Sprint Nextel did not provide figures.

The companies are legally entitled to charge for "reasonable expenses" incurred complying with police.

But that doesn't mean companies bills alike. For example, Cricket bills police $5.50 per number for text message retrieval, whereas T-Mobile bills $50.

Verizon asks $50 for five days of text message content and Sprint charges $30 per hour of employee work.

For cellphone tower dumps, which give police access to the call information of everyone whose cell signal was routed through a tower in a specific period of time, the pricing is more distinct. Verizon charges nothing for a tower dump, whereas Cricket bills $185 and AT&T charges $75. T-Mobile offers two rates for tower dumps: $100 for raw data or $150 for numbers and "corresponding subscriber information."

AT&T received orders for 600 tower dumps in 2012, compared to 10 for Cricket. T-Mobile said it doesn't track individual search categories and Verizon did not provide a specific number.

It's difficult to say why the pricing differs. However, it's possible larger companies are able to perform the functions with greater ease.

"In the majority of instances," said Verizon Wireless General Counsel William Petersen, the company "does not seek reimbursement for responding to law enforcement requests."

In addition to text message retrieval, the other surveillance services Verizon Wireless bills for are wiretap, pen register and trap and trace orders.

Each of the companies cited their legal entitlement to be reimbursed.

"Cricket is frequently not paid on the invoices it submits to law enforcement," noted Robert Irving, the company's chief legal and administrative officer.

"Sprint collects fees that are fully permitted by law," said the company's vice president for government affairs, Charles McKee, in a letter to Markey. "We would be happy to meet with you to discuss this issue further."

Markey, who asked the companies a series of questions about surveillance services, said he plans to introduce legislation to standardize company data retention policies and force tower dumps to be more tailored.

"We need a Fourth Amendment for the 21st century," Markey said in a statement. "Disclosure of personal information from wireless devices raises significant legal and privacy concerns, particularly for innocent consumers."

The data requests reported Monday by Markey were in most cases made by local, state or federal law enforcement with a search warrant or subpoena.

The data does not include information voluntarily divulged by the companies about international calls placed by Americans. The New York Times reported Nov. 7 that AT&T has a $10 million annual contract with the Central Intelligence Agency for access to its overseas call data.

The data also omits the bulk collection of American phone records by the National Security Agency. The NSA indiscriminately collects phone metadata from companies using Foreign Intelligence Surveillance Court orders. The NSA says those records are only searched as part of terrorism-related investigations.

The American Civil Liberties Union, which is suing to stop the NSA phone-record collection, expressed concern Monday and urged reform to the 1986 Electronic Communications Privacy Act, which allows police access to electronic communications older than 180 days without a warrant.

"Our mobile devices quite literally store our most intimate thoughts as well as the details of our personal lives," said Christopher Calabrese, legislative counsel at the ACLU's Washington Legislative Office. "The idea that police can obtain such a rich treasure trove of data about any one of us without appropriate judicial oversight should send shivers down our spines."