For optimizing Internet access resources, a method and systems for sharing network access capacities across Internet service providers is disclosed. According to the method of the invention, a client service provider (CSP) may hire accesses to points of presence belonging to a master service provider (MSP) while maintaining a constant security level and providing connection accounting means. When a CSP's subscriber sends an access request to a MSP, the MSP analyzes the subscriber's realm and checks the capacities allocated to the subscriber's CSP. If connection is allowed, the MSP sends an authentication request to the CSP. If the subscriber is authenticated, the MSP launches an accounting process based on the subscriber's realm while the CSP may launch an accounting process associated with the subscriber identifier. Thus, the MSP does not need to maintain a database comprising information relative to the CSP's subscribers.