AT&T SYSTEM 25 Manual page 160

Release
Release is used when the attendant extends calls. It releases the attendant from the
connection to the calling and called parties and completes the call transfer. There are
two types of Release: Manual and Automatic.
Manual Release: The attendant presses RELEASE to invoke the feature.
Automatic Release: Simplifies the attendant procedures by eliminating the need for pressing
RELEASE while extending calls. When the attendant selects any new call appearance (such
as LOOP, SYSTEM ACCESS, or FLEX DSS) while START is active, the call is automatically
released. Automatic Release is standard for the DTAC, but optional for the SLAC. A SLAC
can have either Automatic Hold or Automatic Release.
The system will not release the call to reorder or dial tone. However, it will release the call
to busy tone. In this case, if the call is a trunk call, the system will camp-on the call; if the
call is an inside call, the calling party will hear busy tone.
See the entries for "Extending Calls" on pages 3-17 and 3-21 and "Automatic Release and
Automatic Hold" on page 3-5 for additional information.
Release 3-43