Sometimes you're trying to establish a connection with a remote user who's running Speak Freely, but who's accidentally turned the volume down to zero or, as happens on Sun workstations, diverted output from the speaker to the headphones and forgotten to return it to the speaker when taking off the 'phones. Selecting the Connection/Ring menu item sends the "Ring sound file", the first packet of which will contain a flag which causes the receiving machine to try to get the user's attention. Speak Freely, upon receiving such a packet, sets the output volume to the maximum value if the Options/Workarounds/Audio/Set Maximum Volume on Ring menu item is checked; a Sun workstation diverts audio output to the speaker and sets output volume to the default level.
The Ring File can be any file you could send with Connection/Send Sound File.... The first time you use Ring, a dialogue appears which invites you to designate a sound file as the Ring file; subsequent Ring requests use that file without prompting you. You can change the Ring file at any time with the Options/Ring File Name... menu item.
It is impolite to ring a user without first seeing if a regular hail elicits a response.