A security feature enabling a host to not only disconnect a remote caller after a positive connection but also recall the remote computer, usually for security verification. Call-backs are typically limited to previously stored telephone numbers, thus enabling connection only for authorized usage. This technology is used to effectively block an attack path in which a cracker dials in to an organization’s Remote Access Service provided for legitimate organizational users and gains access by using a stolen or guessed username/password combination. Symantec Security Response. Glossary. [Online, July 15, 2004.] Symantec Security Response Website. http://securityresponse.symantec.com/avcenter/refa.html.