A system, method, and computer program are provided for authenticating a customer using a network provided by another service provider. In use, a message associated with a customer of a second network service provider is received from a first network service provider. Further, the message indicates usage by the customer of a network provided by the first network service provider. Additionally, in response to the receipt of the message, a request is sent from the second network service provider to the customer for authentication information. In addition, it is determined whether a valid response to the request is received by the second network service provider. Furthermore, based on the determination, the usage by the customer of the network provided by the first network service provider is conditionally blocked.