Hotline
A:) In telecommunication, a hotline is a point-to-point communications link in which a call is automatically originated to the preselected destination without any additional action by the user when the end instrument goes off-hook.
Note 1: Hotlines cannot be used to originate calls other than to preselected destinations.
Note 2: Various priority services that require dialing are not properly termed "hotlines." Synonyms automatic signaling service, off-hook service.
Source: from Federal Standard 1037C
B:) Hotline is also a pioneer in File Sharing and P2P tool which offers central servers over Hotline protocol and several clients.