A system includes a first computer system (FCS) configured to receive an authentication request of a user with respect to the first authentication system (FAS), and communicate an unsuccessful authentication attempt. In response, a bridge computer system (BCS), is configured to request a user ID and receive at least the user ID; identify an address of a second computer system (SCS) based on the user ID; and initiate the second authentication system (SAS) using the address. The SCS, if the user has been successfully authenticated with respect to the SAS, is configured to communicate successful authentication to the BCS; and in response, the BCS is configured to send the FAS a confirmation message, and the FCS is configured to treat the user as authenticated.