A "lock-and-key" consumer billing data protection capability is provided to telemarketing and electronic marketing systems which are based upon previously-acquired consumer lists. The lists contain encrypted partial billing information for each consumer, which is insufficient to access the consumer's account. Thus, at the time a consumer is offered a product or service, the telemarketer, the electronic marketer, and any entity hired to perform billing operations for such consumer purchases all remain "locked" out from accessing the consumer's account. When the consumer wishes to authorize the purchase of an offered product or service, the consumer must provide the "key" to the consumer's account, which is the key necessary to decrypt the encrypted partial billing information and also the missing billing information not acquired from the list provider.