Information on incoming and outgoing calls is collected in a database as the month goes on, but the call data record doesn't exist until someone initiates a query to bring that data together with the customer's name, address, and account information, Neeley said. Then the bill goes out, on paper or as an e-mail message, for the customer's eyes only.

Carriers also need to be able to generate a call data record in response to a subpoena or a police search with a warrant, Neeley said.

But that doesn't mean that no one inside a mobile operator can, technically, create a call data record for their own curiosity, Neeley said. Even if the data is encrypted, some administrators and other employees will have passwords to view it.

Comverse, which provides billing software to mobile operators around the world, offers many tools for carriers to both secure their subscriber records from unauthorized users and keep records on what authorized users do with them, said Senior Vice President Kurt Silverman.

"In our systems, we'll know what you've done, if you did anything interesting," Silverman said. Verizon does not use Comverse's software, he said.