An optional feature supported by the Remote Access Service (RAS) on Microsoft Windows NT servers and the Routing and Remote Access feature of Windows 2000 servers. Callback provides an extra layer of security for users dialing in to a remote access server. When callback is configured, the client software dials in to a remote access server and has the user’s credentials authenticated. The remote access server then disconnects the client and calls the client back at a prespecified phone number. Callback might be configured:
In Windows 2000, the phone number specified for callback is called the Caller ID number.
Windows NT remote access servers configured for callback will call the dial-in client back after a preconfigured time interval of 12 seconds. This callback interval can be modified by editing the registry. See Microsoft TechNet information on callback for more details.