CPNI (customer proprietary network information)

The carrier's data about a specific customer's service and usage. The FCC governs the usage of CPNI. Generally, information about a customer's account is considered proprietary until the customer authorizes its use. (Cingular)

Customer proprietary network information (CPNI) is the data collected by telecommunications corporations about a consumer's telephone calls. It includes the time, date, duration and destination number of each call, the type of network a consumer subscribes to, and any other information that appears on the consumer's telephone bill.

Telemarketers working on behalf of telephone companies, attempting to either win back a customer or upsell a customer with more services must ask the customer's consent before accessing the billing information, before using that information to offer an upsell or any change of services. Uusually, this is done right at the beginning of the call from the telemarketer to the telephone subscriber.

(Wikipedia)